GEOTECHNICAL ENGINEERING REPORT CABRILLO PAVILION … · GEOTECHNICAL ENGINEERING REPORT CABRILLO...

FUGRO CONSULTANTS, INC.

GEOTECHNICAL ENGINEERING REPORT CABRILLO PAVILION AND BATHHOUSE

RENOVATION PROJECT SANTA BARBARA, CALIFORNIA

Prepared for: THE CITY OF SANTA BARBARA

February 2015 Fugro Job No. 04.62140134

February 23, 2015 Project No. 04.62140134

The City of Santa Barbara Parks and Recreation Department 620 Laguna Street Santa Barbara, California 93101-1656

Attention: Mr. Justin Van Mullem, Associate Planner

Subject: Geotechnical Engineering Report, Cabrillo Pavilion and Bathhouse Renovation Project, Santa Barbara, California

Dear Mr. Van Mullem:

Fugro Consultants, Inc. (Fugro) has prepared this geotechnical engineering report to provide input into the design and construction of new retrofit foundations, site retaining walls, pavements, and storm water runoff infiltration Best Management Practices (BMPs) planned as part of the Cabrillo Pavilion and Bathhouse Renovation Project in Santa Barbara, California. Our report also provides input on seismicity and geologic hazards and evaluating existing structure shallow foundations.

Our work was performed in general accordance with our revised proposal dated October 27, 2014, and authorized by City of Santa Barbara (City) agreement number 25,024 executed on November 11, 2014.

We appreciate the opportunity to provide our services on this project. Please contact the undersigned if you have questions regarding this report or require additional information.

Sincerely,


Justin R. Martos, PE Gregory S. Denlinger, GE Senior Staff Engineer Principal Geotechnical Engineer

Copies Submitted: (6) Addressee and pdf, sent via email


4820 McGrath Street, Suite 100 Ventura, California 93003-7778

Tel: (805) 650-7000 Fax: (805) 650-7010

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

City of Santa Barbara February 23, 2015 (Project No. 04.62140134)

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CONTENTS

Page

1.0 INTRODUCTION ........................................................................................................ 11.1 Project Description ............................................................................................ 11.2 Work Performed ................................................................................................ 2

1.2.1 Project Initiation and Data Review ........................................................ 21.2.2 Utility Clearance and Health and Safety ................................................ 31.2.3 Subsurface Exploration ......................................................................... 31.2.4 Bore Hole Percolation Testing ............................................................... 31.2.5 Laboratory Testing ................................................................................ 31.2.6 Geotechnical Evaluations and Reporting .............................................. 4

2.0 FINDINGS .................................................................................................................. 42.1 Site Conditions .................................................................................................. 42.2 Subsurface Conditions ...................................................................................... 5

2.2.1 Geologic Setting .................................................................................... 52.2.2 Subsurface Conditions .......................................................................... 52.2.3 Groundwater .......................................................................................... 52.2.4 Shear Wave Velocity Measurements .................................................... 72.2.5 Geotechnical Profile .............................................................................. 8

3.0 SEISMICITY AND GEOLOGIC HAZARDS ................................................................ 83.1 Faulting .............................................................................................................. 83.2 Strong Ground Motion ....................................................................................... 9

3.2.1 Probabilistic Seismic Hazard ................................................................. 93.2.2 ASCE 7-10/CBC Seismic Design Parameters ....................................... 103.2.3 Seismic Parameters for ASCE 41-13 Seismic Retrofit Evaluation ........ 11

3.3 Liquefaction Potential ........................................................................................ 113.3.1 Liquefaction Triggering Evaluation ........................................................ 113.3.2 Estimated Consequences of Liquefaction ............................................. 12

3.4 Seismic Settlement of Unsaturated Soils .......................................................... 133.5 Tsunami ............................................................................................................. 133.6 Expansive Soil ................................................................................................... 14

4.0 SURFACE WATER PERCOLATION TESTING AND EVALUATION ........................ 144.1.1 Hollow Stem-Auger Drill Holes .............................................................. 144.1.2 Percolation Testing ................................................................................ 154.1.3 Findings ................................................................................................. 16

5.0 CONCLUSIONS AND RECOMMENDATIONS .......................................................... 175.1 Summary of FIndings ........................................................................................ 175.2 Introduction ........................................................................................................ 185.3 General Earthwork and Grading ........................................................................ 19

5.3.1 Site Preparation ..................................................................................... 195.3.2 Excavation Considerations .................................................................... 19


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5.3.3 Remedial Grading and Overexcavation ................................................ 195.3.4 Subgrade Preparation ........................................................................... 205.3.5 Special Subgrade Stabilization Measures ............................................. 215.3.6 Fill Selection, Placement, and Compaction ........................................... 21

5.4 Design Input for New Non-Retrofit Shallow Foundations .................................. 225.4.1 Cast-In Drill Hole Piles .......................................................................... 225.4.2 Axial Capacity ........................................................................................ 225.4.3 Uplift Resistance ................................................................................... 235.4.4 Settlement from Axial Compression and Tension Loads ....................... 235.4.5 Pile Resistance to Lateral Loads ........................................................... 23

5.5 Retrofit Design Input for Existing Foundations .................................................. 245.5.1 General .................................................................................................. 245.5.2 Methodology .......................................................................................... 255.5.3 Soil Properties ....................................................................................... 255.5.4 Uncertainty ............................................................................................ 26

5.6 Design Input for New Non-Building Retrofit Shallow Foundations .................... 265.6.1 General .................................................................................................. 265.6.2 Dimensions ............................................................................................ 275.6.3 Ultimate Bearing Pressure .................................................................... 275.6.4 Allowable Bearing Pressure .................................................................. 275.6.5 Foundation Settlement .......................................................................... 275.6.6 Sliding and Passive Resistance ............................................................ 28

5.7 Retaining Wall Design ....................................................................................... 285.7.1 Lateral Earth Pressures for Cantilevered Retaining Walls .................... 285.7.2 Surcharge Loads ................................................................................... 295.7.3 Drainage ................................................................................................ 295.7.4 Dynamic Lateral Earth Pressure ........................................................... 29

5.8 Floor Slabs ........................................................................................................ 305.8.1 General .................................................................................................. 305.8.2 Vapor Barrier ......................................................................................... 305.8.3 Granular Fill Above Vapor Barrier ......................................................... 315.8.4 Capillary Break and Non-Expansive Soils Below Vapor Barrier ............ 315.8.5 Mold ....................................................................................................... 31

5.9 Flexible Pavement Design ................................................................................. 315.10 Construction Considerations ............................................................................. 32

5.10.1 Existing Utilities ..................................................................................... 325.10.2 Groundwater and Dewatering ............................................................... 325.10.3 Temporary Slopes and Support ............................................................ 335.10.4 Cast in Drilled Hole Piles ....................................................................... 335.10.5 Surface Drainage Considerations ......................................................... 345.10.6 Suggested Materials Specifications ...................................................... 34

5.11 Corrosion ........................................................................................................... 355.11.1 Cement Type ......................................................................................... 365.11.2 Ferrous Materials .................................................................................. 36

5.12 Geologic and Geotechnical Consequences from Sea Level Rise ..................... 36


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5.12.1 Static Impacts ........................................................................................ 365.12.2 Seismic Impacts .................................................................................... 375.12.3 Concept-Level Strategies for Mitigating Shallow Liquefaction............... 385.12.4 Suggested Additional Structural Footprint ............................................. 40

6.0 LIMITATIONS ............................................................................................................. 416.1 Report Use ........................................................................................................ 416.2 Potential Variation of Subsurface Conditions .................................................... 416.3 Hazardous Materials ......................................................................................... 416.4 Local Practice .................................................................................................... 416.5 Plan Review ...................................................................................................... 426.6 Construction Monitoring .................................................................................... 42

7.0 REFERENCES ........................................................................................................... 43

TABLES

Page

Table 1. Summary of Groundwater, Caving, and Tide Elevation Measurements ........................ 6Table 2. Idealized Geotechnical Profile ....................................................................................... 8Table 3. Summary of USGS Probabilistic Seismic Hazard Deaggregation Results .................... 9Table 4. Summary of 2013 CBC Seismic Design Parameters ................................................... 10Table 5. Field Percolation Test Results ..................................................................................... 16Table 6. Soil Spring Geotechnical Input Parameters ................................................................. 26Table 7. Lateral Earth Pressures for Retaining Wall Design ...................................................... 29Table 8. Recommended Asphalt Pavement Sections ................................................................ 32Table 9. Corrosion Test Results ................................................................................................ 36

PLATES

Plate

Vicinity Map ......................................................................................................................... 1 Subsurface Exploration and Location Map ......................................................................... 2 Subsurface Profile A-A ...................................................................................................... 3 Subsurface Profile B-B ....................................................................................................... 4 Subsurface Profile C-C .................................................................................................. 5 Subsurface Profile D-D ...................................................................................................... 6 Tsunami Inundation Map .................................................................................................... 7


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APPENDICES

APPENDIX A SUBSURFACE EXPLORATION Drill Hole Logs ..................................................................................................... A-1 through A-4 Key to Terms & Symbols Used on Logs ................................................................................. A-5 CPT Logs .......................................................................................................... A-6 through A-13 Key to CPT Interpretation ..................................................................................................... A-14

APPENDIX B LABORATORY TESTING Summary of Laboratory Test Results ..................................................................................... B-1 Grain Size Curves .................................................................................................................. B-2 Plasticity Chart ....................................................................................................................... B-3 Direct Shear Test results ........................................................................................................ B-4 Consolidation .......................................................................................................................... B-5

APPENDIX C SCPT DATA Shear Wave Velocity Data ...................................................................................................... C-1

APPENDIX D GROUND MOTION DATA ASCE 41-13 Seismic Design Parameters ...................................................... D-1a through D-1d ASCE 41-13 BSE-2E Seismic Design Parameters ......................................... D-2a through D-2d USGS PSH Deaggregation 475 YR Return period .............................................................. D-3 USGS PSH Deaggregation 2475 YR Return period ............................................................ D-4 ASCE 7-10 Seismic Design Parameters ......................................................... D-5a through D-5f

APPENDIX E LIQUEFACTION TRIGGERING ANALYSES Liquefaction Analysis Log of CPT ........................................................................ E-1 through E-8 Liquefaction Analysis Log of CPT ...................................................................... E-9 through E-16 Key to Liquefaction Logs ...................................................................................................... E-17 Liquefaction Susceptibility (Bray and Sancio, 2006) ............................................................. E-18 Liquefaction Analysis Log of CPT with Groundwater Rise .............................. E-19 through E-42

APPENDIX F PERCOLATION TEST CALCULATIONS Percolation Test Calculations ................................................................................................. F-1

APPENDIX G AXIAL CAPACITY OF CIDH PILES CIDH Pile Ultimate Axial Capacity .......................................................................................... G-1


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APPENDIX H LATERAL PILE ANALYSES Lateral Pile Capacity Results- 18 inch Fixed Head Pile .......................................................... H-1 Lateral Pile Capacity Results- 18 inch Free Head Pile ........................................................... H-2 Lateral Pile Capacity Results- 24 inch Fixed Head Pile .......................................................... H-3 Lateral Pile Capacity Results- 24 inch Free Head Pile ........................................................... H-4 Lateral Pile Capacity Results- 30 inch Fixed Head Pile .......................................................... H-5 Lateral Pile Capacity Results- 30 inch Free Head Pile ........................................................... H-6 Lateral Soil Load Transfer (p-y curves)- 18-inch Pile ............................................................. H-7 Lateral Soil Load Transfer (p-y curves)- 24 inch Pile .............................................................. H-8 Lateral Soil Load Transfer (p-y curves)- 30 inch Pile .............................................................. H-9 Lateral Pile Capacity Results- 18 inch Fixed Head Pile ........................................................ H-10 Lateral Pile Capacity Results- 18 inch Free Head Pile ......................................................... H-11 Lateral Pile Capacity Results- 24 inch Fixed Head Pile ........................................................ H-12 Lateral Pile Capacity Results- 24 inch Free Head Pile ......................................................... H-13 Lateral Pile Capacity Results- 30 inch Fixed Head Pile ........................................................ H-14 Lateral Pile Capacity Results- 30 inch Free Head Pile ......................................................... H-15 Lateral Soil Load Transfer (p-y curves)- 18-inch Pile ........................................................... H-16 Lateral Soil Load Transfer (p-y curves)- 24 inch Pile ............................................................ H-17 Lateral Soil Load Transfer (p-y curves)- 30 inch Pile ............................................................ H-18


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1.0 INTRODUCTION

1.1 PROJECT DESCRIPTION

The Cabrillo Pavilion and Bathhouse project is located in the City of Santa Barbara at 1118 East Cabrillo Boulevard. The structure is on the ocean side of East Cabrillo Boulevard between Ninos Drive and Corona Del Mar. The general location of the site relative to local geographic features is shown on Plate 1 - Vicinity Map.

The existing structure was constructed in 1926 and consists of a two-story central core that is flanked by single story elements on the east and west sides. The structure is constructed of reinforced concrete and wood framing/stucco with a slab on grade and is supported on shallow continuous perimeter shallow foundations, interior grade beams, and isolated pad footings. On the basis of information provided in the as-build plans (The David Grays, 1926), perimeter footings are typically 2-feet wide and interior grade beams range from about 18 inches to about 4 feet wide. Isolated pad footings range from about 4 to 7 feet square. We estimate the embedment depth for the perimeter footings and grade beams to range from about 2 to 4 feet below the first floor slab level. We estimate pad footings are embedded about 4 feet below the first floor slab.

As-built plans suggest that individual column loads range from about 24 to 79 kips. On the basis of those column load ranges, we estimate the applied bearing pressure on the pad footings to be about 1,500 to 2,000 psf. From that, we have inferred the applied loading on the perimeter grade footings and grade beams are also in the range of 1,500 to 2,000 psf.

The structure has an overall footprint of about 16,500 square feet. The ground floor level is at an elevation of about +14 feet (NAVD 1988) and the main building entrance is accessed from East Cabrillo Boulevard that is an al elevation of about +25 feet. The beach promenade is located on the south side of the building and consists of a concrete paved walkway. Entrances to the existing restaurant, lifeguards quarters, and mens and womens locker rooms are along the south side of the building. Existing asphalt-paved parking lots are present on the east and west sides of the building. Data from the as-build plans suggest the structure was modified after 1926 to provide an entrance to the building from East Cabrillo Boulevard and the second story structure was extended to the south to enclose a former outdoor terrace.

We understand that a paved road (East Boulevard) once existed in front of the bathhouse and the structural section remains in-place below the beach promenade walkway and extends east and west of the project site. Moffatt & Nichol (2014) indicates the road was relocated to the north side of the bathhouse in 1928 due to shoreline erosion. We also understand that an abandoned and buried timber seawall and rock revetment is also present on the south side of the structure, east parking lot, and playground/STOA area. Other buried groin-type structures are also present in the beach area east of the site. The playground is constructed over an abandoned concrete wading pool.



We understand the City plans to renovate the existing Cabrillo Pavilion and Bathhouse and restore the facility to its original status as one of Santa Barbaras iconic landmarks and the crown jewel of East Cabrillo Boulevard. We understand work will include various building improvements and structure retrofit, and interior and exterior renovations to enhance public access, and provide a gathering point for citizens and visitors of the City.

We understand that the renovation work will involve new structure elements and structure seismic retrofit. Current plans suggest that new retrofit concrete shear walls and related grade beam foundations are required at various locations in the building footprint. Selected existing foundations are planned to be strengthened or retrofitted with helical anchors/micro piles or drilled shafts. Principal new structure elements are anticipated to consist of the following:

Redesigning the main building entrance from East Cabrillo Boulevard;

Demolishing and replacing the existing trash enclosure;

A new condensing unit enclosure located at the northwest portion of the building

Site work to accommodate a redesigned northeast service walkway and event staging area along the northeast side of the building;

Modifications to the east and west parking lots;

Renovation of the existing outdoor showers;

Renovation of the existing covered walkway (STOA) near the playground area; and

New composite material boardwalks at the beach along the southern edge of the west parking lot that will connect to the Chase Palm Park corridor and extending from the promenade towards the beach.

Other work will consist of foundation perimeter waterproofing, repairs to the building faade, a new elevator, and site improvements for ADA access.

1.2 WORK PERFORMED

Our scope of services for the geotechnical study was presented in our proposal dated October 27, 2014. The work was authorized by the City of Santa Barbaras (City) agreement number 25,024 executed on November 11, 2014. Work performed by Fugro for this study included the following tasks:

1.2.1 Project Initiation and Data Review

We consulted with City staff and the project team regarding the project, the project objectives, and our approach to providing geotechnical services, and to define the goals for the project. We also reviewed preliminary project plans, the coastal hazards report prepared by Moffatt & Nichol Engineers (Moffatt & Nichol 2014), historical geotechnical boring data and beach erosion profiles from 1933 provided to us by the City, and published regional geologic



maps. We used the information provided in those reports to develop a general understanding of the site, the proposed project, and geologic conditions.

1.2.2 Utility Clearance and Health and Safety

Prior to conducting subsurface exploration we prepared a health and safety plan for the onsite project operations. We delineated areas for the proposed explorations and reviewed the borings locations with City staff. We also contacted Underground Services Alert (USA) and requested that they notify their member agencies that own and maintain utilities in the project area to mark/locate their facilities relative to the delineated exploration areas.

1.2.3 Subsurface Exploration

Our subsurface exploration program was performed in two phases of work with the first phase consisting of advancing five static cone penetration test (CPT) soundings and two seismic cone penetration test (SCPT) soundings on November 18 and 19, 2014. A second phase of work consisted of drilling and sampling four hollow-stem-auger drill holes to depths ranging from approximately 20 to 60 feet below the existing ground surface. The drilling and sampling work was performed on December 18 and 19, 2014. In addition, as part of the hollow-stem-auger drilling effort, we drilled and constructed two shallow bore hole infiltrometer test wells for percolation/infiltration testing.

Approximate locations of the CPTs, SCPTs, drill holes and percolation test wells are shown on Plate 2 - Site Exploration Map. Logs of the CPTs, SCPTs and drill holes and additional information pertaining to our field exploration program are presented in Appendix A - Subsurface Exploration.

1.2.4 Bore Hole Percolation Testing

We conducted two percolation tests at the site to evaluate the storm water infiltration capacity of the near-surface on-site soils. We performed these tests at percolation test hole locations P-01 and P-02 on December 22, 2014. The approximate locations of the percolation tests are shown on Plate 2. Each test was carried out utilizing a falling-head procedure in general accordance with the provisions outlined in the City of Santa Barbara's Storm Water BMP Guidance Manual (City of Santa Barbara, 2008). Additional information on the tests, findings and a discussion of the test results are summarized in this report.

1.2.5 Laboratory Testing

Geotechnical laboratory tests were performed on selected soil samples obtained from the soil drill holes to estimate the engineering properties of the materials encountered. Information on the tests performed and the test results are provided in Appendix B - Laboratory Testing.



1.2.6 Geotechnical Evaluations and Reporting

We prepared this geotechnical engineering report to present the field and laboratory data collected as part of this study and provide opinions and design recommendations regarding:

Characterization of the geotechnical conditions and groundwater elevations at the site;

Geologic cross sections at selected locations to graphically present the topographic and subsurface data;

Response spectra for performance-based analyses (BSE-1E and BSE-2E) in accordance with ASCE 41-13;

Geotechnical seismic data for the site in accordance with the 2013 California Building Code;

General geologic hazards such as strong ground motion, fault rupture potential, liquefaction and seismic settlement;

Bearing capacity, settlement, and soil spring values (vertical and lateral) for existing and new retrofit shallow foundations;

Axial and uplift capacity and soil spring values for new retrofit deep foundations (consisting of either cast-in-drill-hole [CIDH] piles or micropiles);

Standard geotechnical input [working stress design] for new shallow foundations/footings [such as bearing capacity, settlement, and lateral resistance]

Working stress design lateral earth pressures for new ancillary exterior retaining walls;

General input to pavements and hardscape; Soil corrosion potential; Foundation drainage; Qualitative evaluation of foundation performance and impacts to foundations

from sea level rise; Site development, earthwork and grading, compaction and fill placement, and

pavement/hardscape subgrade. Infiltration rate at each test location and calculation method used, and Qualitative input regarding the use of infiltration BMPs at the site.

2.0 FINDINGS

2.1 SITE CONDITIONS

As described previously, the site is located at 1118 East Cabrillo Boulevard in the City of Santa Barbara. The existing bathhouse is flanked by East Cabrillo Boulevard on the north, asphalt-paved parking lots on the east and west, and the concrete-paved pedestrian promenade and sandy beach on the south. Topographically, East Cabrillo Boulevard is about at el. +25 feet, the adjacent parking lots are at about el. +13 to +16 feet, and the ground floor the



bathhouse is at about el. +15 feet (NAVD 1988). The grade at East Cabrillo Boulevard descends to about el. +15 to +16 at the north edge of the east and west parking lots and at the north end of the bathhouse building. The existing slope that descends from East Cabrillo Boulevard is approximately 7 to 10 feet high and the slope inclination varies from about 2-1/2h:1v to 3h:1v. Sandy beach is present south of the parking lots and bathhouse building. The Pacific Ocean is located about 150 feet south of the building.

2.2 SUBSURFACE CONDITIONS

2.2.1 Geologic Setting

Minor et al. (2009) maps the conditions at the site as consisting of younger and older alluvial soils at and north of the slope break at East Cabrillo Boulevard and extending east-west along the northern edge of the parking lot areas, with beach sand deposits to the south. The western portion of the site is located near the pre-settlement estero associated with Sycamore Creek that was reclaimed and filled to accommodate access and development. The grade rises from west to east along Cabrillo Boulevard reflecting the uplift associated with a mapped anticline that extends northwest-southeast through the elevated terrain at the Santa Barbara zoo located northeast of the site. Minor et al. (2009) map older alluvial soils in the elevated terrain at the zoo and at the Hyatt Hotel to the north across East Cabrillo Boulevard.

2.2.2 Subsurface Conditions

On the basis of our interpretation of the CPT/SCPT sounding and drill hole data, the subsurface conditions at the Cabrillo Pavilion and Bathhouse generally consist of dense to very dense sand (SP-SM) to silty sand (SM) interbedded with one to two fine-grain layers of stiff to very stiff clayey silt (ML) to lean clay (CL). Some thin sand seams are present in the fine-grained units. The fine-grain layers appear to occur at variable depths and generally range from about 5 feet thick to about 20 feet thick. Geotechnical cross sections depicting the subsurface conditions developed from the CPT/SCPT soundings and drill holes are provided on Plates 4 through 6. The variable depth locations of the fine-grained units are apparent in the cross sections.

In general, we interpret the coarse-grained sand to silty sand units to represent beach sand deposits. Considering the relatively high stiffness of the fine-grained layers, we interpret that these units are likely non-marine/non-estuarine and were likely deposited in a terrestrial environment during periods of sea level fluctuation. Based on past projects in the area, the fine grain units appear similar to those previously described as older alluvium. The variable depth positions of the fine grained layers in the sections likely occur as a result of past differential erosion across the site. We are not aware of any published information to suggest that the variable depths of the fine-grained units are fault related.

2.2.3 Groundwater

Current Conditions. Groundwater was encountered in the four geotechnical drill holes excavated and logged for the project. The depth to groundwater encountered in our drill holes



in the east and west parking lot areas (DH-2, DH-3, and DH-4) generally ranged from about 7 to 9 feet below the existing ground surface (bgs). The depth to groundwater measured in drill hole Dh-1 excavated on East Cabrillo Boulevard was about 16-1/2 feet. Based on the measured depth to water and the site elevation data provided to us by the City, we estimate the groundwater elevation at the time of our study ranged from about el. +5 to +6 feet.

This depth range is generally consistent with the manually measured depths to caving material in the CPT sounding holes (hole formed after the removal of the CPT rods). The depth to caving ranged from about 7 to 8 feet below the ground surface (relative to the grade in the parking lots). We interpret the depth to caving at this site to be quasi representative of the depth to groundwater.

Table 1 below summarizes the caving and water level depth measurement collected during site exploration with respect to tide levels at the times of measurement. Tide level data was obtained through the National Oceanic and Atmospheric Administrations (NOAA) online web tool. The tide data presented below was collected at the local Santa Barbara station and represents elevations relative to NAVD88.

Table 1. Summary of Groundwater, Caving, and Tide Elevation Measurements

Exploration Surface El. (ft NAVD88)4 Approximate Date/Time GW Depth

(ft) GW El.

(ft NAVD88) Tide El.2

(ft NAVD88) DH-01 +23.01 9:30 AM 12/18/2014 16.5 +6.5 +3.7 DH-02 +13.5 4:30 PM 12/18/2014 7.0 +6.5 +1.9 DH-03 +14.5 9:30 AM 12/19/2014 7.0 +7.5 +4.5 DH-04 +15.5 12:10 PM 12/19/2014 9.0 +6.5 +1.0

CPT-01 +23.0 10:50 AM 11/18/2014 14.0* +9.03 +2.3 CPT-02 +22.5 11:55 AM 11/18/2014 16.0* +6.53 +1.4 CPT-03 +13.0 1:00 PM 11/18/2014 15.0* -2.03 +0.9 CPT-04 +12.5 2:10 PM 11/18/2014 1.0* +11.53 +1.0 CPT-05 +15.0 3:00 PM 11/18/2014 7.0* +8.03 +1.5

CPT-05A +14.5 4:20 PM 11/18/2014 9.0* +5.53 +2.5 CPT-06 +13.5 9:40 AM 11/19/2014 7.5* +6.03 +3.8 CPT-07 +14.5 10:50 AM 11/19/2014 8.5 +6.0 +2.4

1) Assumed, and based on limited City-provided topography adjacent to the sidewalk at Cabrillo Blvd. 2) Tide elevations determined based upon NOAA measurements taken at 6-minute intervals from the Santa Barbara Station. 3) Denotes caving depth in CPT holes where groundwater was not directly measured. 4) Topography at exploration locations based on City-provided survey data

As shown above, the estimated groundwater elevation (excluding the outliers at CPT-3, and CPT-4) ranges from about el. +5.5 to +9 feet with an average of about 6.8 feet. The average value falls to about el. +6.5 feet if the data from CPT-1 is also excluded.

We are not aware of any industry standard for evaluating variations in groundwater level from tidal influences. However, the problem can be modeled and evaluated analytically using readily available groundwater modeling software. Some limited research we have reviewed for in response to this comment indicates that tidal influence plays a relatively small role in groundwater fluctuation at distances a few to several hundred feet from the water source. Therefore, the water tables response to tidal influence at the site will likely be delayed and significantly attenuated considering the distance between the ocean and the structure location.



This conclusion appears to be supported by our review of local tidal fluctuation with respect to the water levels measured in the drill holes excavated for this study on December 18 and 19, 2014.

For the purpose of project planning and design, we recommend a typical depth to groundwater of about 7 feet (relative to the parking lots and building pad) be assumed. We estimate that depth to groundwater corresponds to an elevation of about el. +6 feet. However, groundwater depths may fluctuate through time due to seasonal precipitation levels, tide level, storm surges and sea level rise.

Possible Groundwater Changes From Sea Level Rise. Moffatt & Nichol (2014) provides an assessment of potential flooding and erosion impacts and from potential future sea level rise. The report estimates a sea level rise at the site in the year 2065 ranging from a low estimate of about 0.6 feet to a high estimate of about 2.9 feet with a projected sea level rise of about 3.1 feet in the year 2100. The report also suggests that the bathhouse structure has a moderate level of vulnerability from flooding an inundation currently and a projected high level of vulnerability in 2065. Moffatt & Nichol (2014) recommends waterproofing the foundation and building perimeter to mitigate the impacts of flooding on the bathhouse structure and provides a general program to adaptively manage flooding and sea level rise risks to the bathhouse and promenade.

We expect that sea level rise will likely affect the static groundwater level over time. The Moffatt & Nichol report does not provide a prediction of how sea level rise might affect the static groundwater level, but it is possible that the relationship between sea level rise and groundwater level could be linear. The groundwater response at the site due to a long term sustained rise in sea level is difficult to determine without more detailed knowledge of the backland groundwater conditions. However, in our opinion, a one to one relationship between sea level rise and groundwater table elevation for long term conditions at the project site is probably conservative and appears reasonably justified at this time.

In that case, the groundwater elevation in 2100 could be as much as 3.1 feet higher than the current level. For the values measured in our study, a 3.1-foot increase in groundwater would correlate to a groundwater elevation of about el. +9 feet at the site in 2100. We have assumed an elevation to groundwater considering sea level rise of el. +9 feet for the purpose of providing input to potential impacts to the structure, including impacts from liquefaction.

2.2.4 Shear Wave Velocity Measurements

As described in Section 1.2.3, SCPT shear wave velocity profile measurements were performed at two locations (SCPT-5/5A and SCPT-6) to obtain shear wave velocity profile data for the onsite soils. The SCPTs were performed by Kehoe Testing and Engineering of Huntington Beach, California.

The shear wave velocity profile in the upper 100 feet of soil strata is an important parameter that can be used to categorize the site class per ASCE 7-10 or to modify the site response based upon near surface soil conditions in a site-specific analysis. In general, the



measured shear wave velocities ranged from about 500 to 1000 ft/sec in the upper 50 feet increasing to about 800 to 1500 ft/sec between 50 feet and 100 feet. On the basis of the SCPT data, in our opinion the Vs30 (shear wave velocity in the upper 30 m or 100 ft) at the site can be estimated to 870 ft/s. A Vs30 value of 870 ft/s falls in the range of Site Class "D" conditions. Therefore, we developed the design response spectra for the project for Site Class "D" conditions. Shear wave velocity data provided to us by Kehoe Testing for SCPT-5/5A, SCPT-6, are provided in Appendix C SCPT Data.

2.2.5 Geotechnical Profile

We developed a generalized geotechnical profile for the site using the geotechnical data obtained for this project and from our review of past projects in the area. This generalized profile was used as a basis for our evaluation of the proposed new foundations and potential response of the existing foundation system.

Table 2. Idealized Geotechnical Profile

Elevation Interval (feet)

Generalized Soil Material L-Pile Soil Type

Unit Weight

(pcf)

Friction Angle

(degrees)

k

(pci)

14 to 9 (assume foundation subgrade at el. 11 ft)

Medium Dense Silty Fine Sand Sand (Reese) 120 32

Program default value

9 to 6

Medium Dense Silty Fine Sand

(potentially liquefiable if below groundwater level)

Sand (Reese)

Liquefied Sand (per Rollins, for liquefaction evaluation)

60 (buoyant) 32


6 to 3 Medium Dense to Very Dense Silty Fine Sand

Sand (Reese) 60 (buoyant) 32 Program default value

3 to -18 Dense to Very Dense Sand with Silt

Sand (Reese) 60

(buoyant) --


3.0 SEISMICITY AND GEOLOGIC HAZARDS

3.1 FAULTING

Regional compressive forces acting on the Santa Barbara coastal area have resulted in generally east-west trending folds and faults. Gurrola (1998) terms the coastal plain region the Santa Barbara Fold Belt (SBFB). The SBFB is characterized by active folding and buried reverse faulting. The SBFB is formed on the south limb of the Santa Ynez anticlinorium. The Santa Ynez anticlinorium is postulated by Namson and Davis (1992) to be related to a low angle, north dipping ramp of a detachment or dcollement at 10 to 12 kilometers in depth.



According to Gurrola (2004), the closest mapped faults to the project area are the offshore Red Mountain, Rincon Creek, and North Channel Slope Faults, and the onshore Riviera fault, Mission Ridge-Arroyo Parida fault, Santa Ynez fault, Fernald fault, Ortega Fault, Summerland fault, and faults associated with the Santa Barbara Cemetery and Loon Point Anticlines (Cemetery fault and Loon Point fault). With the exception of the Red Mountain, North Channel Slope, Santa Ynez and Mission Ridge-Arroyo Parida faults, these (local) faults are not mapped in the United States Geologic Survey (Petersen, et al, 2008) fault database, and therefore, are not included in our seismic hazard analysis of the site. Maps and descriptions of local faults in the Santa Barbara area are given in Dibblee (1966, 1986), Santa Barbara County (1979, 1991), Gurrola (2003, 2004), and Minor, et al (2009).

Published and unpublished maps do not show faults on or in the immediate vicinity of the project site, nor does the site lie within an Alquist-Priolo fault rupture hazard zone. On the basis of our data review, known active or potentially active faults do not trend toward or traverse the site. The offshore, blind north-dipping North Channel Slope fault and the Red Mountain fault likely extend beneath the site, however, the surface projections of these two faults are offshore to the south, subparallel to the coastline. Other deep blind thrust faults such as the Oakridge-Mid Channel Structure and Channel Island Thrust fault are located farther offshore beneath the Santa Barbara Channel.

3.2 STRONG GROUND MOTION

3.2.1 Probabilistic Seismic Hazard

We performed a probabilistic seismic hazard analysis for the site location using the USGS 2008 Interactive Deaggregations (Beta) web application (USGS, 2008). California Geological Survey (CGS, 2008), Special Publication 117A defers to the USGS website to determine a uniform hazard spectrum for a specified location in terms of latitude and longitude. On the basis of our analyses using the USGS (2008) website application, the peak horizontal ground acceleration (pga) at the project area is estimated to be about 0.52g for an earthquake event with a 475-year return period (10 percent probability of exceedance in 50 years) assuming Site Class D soil conditions. A pga of 0.96g is estimated for an event with a 2,475-year return period (2 percent probability of occurrence in 50 years). Table 3 summarizes the probabilistically estimated strong ground motion parameters for the project site.

Table 3. Summary of USGS Probabilistic Seismic Hazard Deaggregation Results

Return Period (years)

Mean Magnitude (Mw)

Mean Source Distance (km)

Peak Horizontal Ground Acceleration

(g)

475 6.9 9.7 0.52

2,475 7.2 7.2 0.96



3.2.2 ASCE 7-10/CBC Seismic Design Parameters

The proposed structures should be designed to resist the lateral forces generated by earthquake shaking in accordance with local design practice. Seismic design procedures are outlined in Section 1613 of the California Building Code (CBC) and are designed to meet the intent and requirements of ASCE 7. Data collected for our original study and this current scope of work indicate that the subsurface profile is consistent with the criteria for site class D. Table 4 provides seismic design parameters for use with the CBC (2013). These parameters were generated using version 3.1.0 of the U.S. Seismic Design Maps web application available on the USGS website (USGS, 2014).

Table 4. Summary of 2013 CBC Seismic Design Parameters

2013 CBC or ASCE 7-10 Code Section Seismic Parameter Value

--- Latitude N 34.41699

--- Longitude W 119.66898

CBC 2013 Section 1613.3.1 and Figure 1613.3.1(1)

Mapped Acceleration Response Parameter (Ss)

Site Class B 2.880g

CBC 2013 Section 1613.3.1 and Figure 1613.3.1(2)

Mapped Acceleration Response Parameter (S1)

Site Class B 1.010

ASCE 7-10 Chapter 20 Table 20.3-1 Soil Profile Type D

CBC 2013 Section 1613.3.3 and Table 1613.3.3(1) Site Coefficient (Fa) 1.09

CBC 2013 Section 1613.3.3 and Table 1613.3.3(2) Site Coefficient (Fv) 1.64

CBC 2013 Section 1613.3.3 Adjusted Acceleration Response Parameter for Site Class B (Sms) 2.880g

CBC 2013 Section 1613.3.3 Adjusted Acceleration Response Parameter for Site Class B (Sm1) 1.515g

CBC 2013 Section 1613.3.4 Design Spectral Response Acceleration Parameter (SDS) 1.920g

CBC 2013 Section 1613.3.4 Design Spectral Response Acceleration Parameter (SD1) 1.010g

ASCE 7-10 Section 11.8.3 Mapped MCE Geometric Mean (MCEG) Peak Ground Acceleration (PGA) 1.123

ASCE 7-10 Section 11.8.3 Site Coefficient (FPGA) 1.00

ASCE 7-10 Section 11.8.3 Adjusted MCEG Peak Ground Acceleration for Site Class D (PGAM) 1.123



These parameters can be used to construct the Risk-targeted acceleration response spectrum as described in ASCE 7-10. Outputs from the USGS web application for use with ASCE 7-10 are provided in Appendix D Ground Motion Characterization.

3.2.3 Seismic Parameters for ASCE 41-13 Seismic Retrofit Evaluation

We understand the existing structure will be seismically evaluated and retrofitted in accordance with the guidelines provided in ASCE 41-13. We estimated the peak horizontal ground acceleration at the site for earthquake hazard levels for a life safety hazard level (BSE-1E) and collapse prevention (BSE-2E). BSE-1E life safety level corresponds to an earthquake hazard with a probability of 20 percent in a 50-year exposure period and BSE-2E collapse prevention level corresponds to an earthquake hazard of 5 percent probability of exceedance in a 50-year exposure period. Based on the shear wave velocity measurements, the subsurface conditions in the project area correspond to Site Class D conditions as described in ASCE 7-10 and ASCE 41-13. We estimated the peak ground accelerations (PGA) for the two hazard levels using the USGS web application (USGS [2008]) and in accordance with the guidelines provided in ASCE 41-13. The computed PGA values estimated for the site are provided below.

Earthquake Hazard Level

Peak Horizontal Acceleration

Estimated Mean Earthquake Magnitude

BSE-1E 0.40g 6.9

BSE-2E 0.88g 7.0

Output from the USGS web application for use with ASCE 41-13 (including spectral ordinates for short and long periods and other parameters) are provided in Appendix D Ground Motion Characterization.

3.3 LIQUEFACTION POTENTIAL

3.3.1 Liquefaction Triggering Evaluation

Liquefaction is described as the sudden loss of soil strength because of a rapid increase in soil pore water pressures due to cyclic loading during a seismic event. In order for liquefaction to occur, the following three general geotechnical characteristics must be present:

1. Groundwater must be present within the potentially liquefiable zone;

2. Potentially liquefiable soil must meet certain grain size, plasticity, and moisture content characteristics; and

3. Potentially liquefiable soil must be of low to moderate relative density.

If those criteria are met and strong ground motion occurs, then those soils may liquefy, depending upon the intensity and cyclic nature of the strong ground motion.

We used the CPT data and laboratory plasticity data to assess the liquefaction hazard for the project. We performed a liquefaction triggering analysis in accordance with the



procedure outlined by Youd et al (2001) for hazard levels BSE-1E and BSE-2E. We assumed the groundwater level to be at el. +6 feet (estimated current groundwater elevation) for these analyses.

The results of our liquefaction triggering analyses suggest that the dense to dense granular layers below the assumed groundwater level (el. +6 feet) are not susceptible to liquefaction under both the BSE-1E and BSE-2E hazard levels. However, there are some relatively thin, localized granular soil layers at depth within the subsurface profile that are susceptible to liquefaction.

Also our liquefaction triggering analyses suggested that some soils within the fine-grained soil units were susceptible to liquefaction based on the measured CPT tip resistance, friction ratio and Ic (normalized soil behavior type index). Soils with an Ic value of less than 2.6 can be susceptible to liquefaction and the calculated Ic values for these materials are generally less than 2.6. However, it is likely that these fine-grained soils with Ic values of less than 2.6 are more cohesive (clayey) than interpreted from the CPT data and thus are significantly less susceptible to liquefaction than estimated from our analyses and possibly non-liquefiable.

We collected samples of the fine-grained soils that were considered potential susceptible to liquefaction based on our triggering analyses. We tested the materials for plasticity and insitu water content and used the guidelines in Bray and Sancio (2006) to evaluate whether these fine grained soils were susceptible to liquefaction. The ratio of insitu water content to liquid limit and plasticity index data fall within the not susceptible (to liquefaction) range provided in Bray and Sancio (2006). Therefore, we have assumed the fine-grained materials noted as potentially liquefiable in our CPT-focused triggering analyses can be considered as non-liquefiable.

The results of our CPT-focused liquefaction CPT triggering analyses are provided in Appendix E Liquefaction Triggering Analyses. We annotated the fine grained soil layers shown on the Appendix E plates to reflect our opinions that these soils are not susceptible to liquefaction based on the results of laboratory testing. Relevant soil classification data for use with Bray and Sancio (2006) are also provided in Appendix E.

We also evaluated the potential for liquefaction considering the potential for an increase in groundwater level related to sea level rise. A discussion of our analyses and qualitative opinions consequences of coupled sea level rise and liquefaction is provided in Section 5.12.

3.3.2 Estimated Consequences of Liquefaction

Based on our analyses, potential consequences of liquefaction occurring at the site for the current estimated groundwater conditions appear to be limited and would likely consist of minor ground surface settlement of less than an 1 inch. The settlement is generally from liquefaction of the few, relatively thin layers present at depth in the soil profile.

In addition, we believe the potential for lateral spreading and lateral deformation occurring from liquefaction appears remote under the estimated current groundwater conditions (that is groundwater assumed to be at el. +6 feet).



To address the potential liquefaction-related impacts at the site due to the potential range of future sea level rise presented in Moffatt & Nichol (2014), we also assessed the site for liquefaction triggering, settlement, and lateral spreading assuming groundwater levels 0.6, 2.9 and 3.1 feet higher than the assumed current phreatic surface elevation. These sea level rise scenarios reflect low and high potential for the year 2065 and a projected level for 20100, respectively. The results of the CPT-based liquefaction triggering and settlements for these cases are also included in Appendix E.

We estimated the potential consequences of lateral spreading using version 1.7.6.34 of the geotechnical analysis computer software CLIQ (Geologismiki, 2006). The analysis software uses the method described in Zhang et al (2004). In our opinion, the lateral deformation that could occur at the site under the ASCE 41-13 BSE-2E seismic event combined with a 2.9- or 3.1-foot rise in groundwater elevation would likely range from a few inches to about a foot. The potential for lateral deformation for the case of a 0.6-foot sea level rise is not anticipated to be significantly greater than for the current assumed groundwater level conditions (that is groundwater at elevation +6 feet).

3.4 SEISMIC SETTLEMENT OF UNSATURATED SOILS

Seismic settlement of unsaturated soils is generally less significant than that resulting from liquefactions induced settlement displacements. On a qualitative basis, we estimate the potential seismic settlement of the unsaturated granular soils above the current assumed groundwater level to be about 1/2 inch to 1 inch.

3.5 TSUNAMI

A tsunami is a series of sea waves generated by rapid displacement of a large volume of sea water resulting from vertical movements of the seafloor. The displacement may result from seismically-induced vertical warping of the seabed, large scale submarine or coastal landslides, or volcanic eruptions in or near ocean basins. Tsunamis are usually described as local- or distant-sourced.

In the open ocean, distant-source tsunami waves have a very long period and wavelength and can travel at speeds of greater than 300 miles (500 km) per hour. As a tsunami moves into shallow water the wave heights increase and the wavelength and speed decreases. Historical records indicate that the character of tsunami waves varies greatly depending on factors such as the shape of the coastline, coastal seafloor topography, the existence of offshore islands, and the direction of the incoming waves.

Predicting the hazards of tsunamis in the Santa Barbara and Montecito areas is difficult because of their rare occurrence and lack of evidence. However, the project site is located on the coast of the Pacific Ocean and is therefore considered to be vulnerable to the potential hazards of a tsunami event. Thrust or reverse faulting associated with major faults of the western Transverse Ranges are known sources of local tsunamis in southern California (McCulloch, 1985; McCarthy, et al, 1993; Borrero, et al, 2001). In the Santa Barbara Basin to the northwest of the project area, earthquake sources that could generate a tsunami include the



Channel Islands Thrust fault, the North Channel and Pitas Point fault, Red Mountain fault, and the Oak Ridge fault. Submarine landslides on the steep slopes of the offshore inner California Continental Borderland are widespread and another potential source of tsunami activity in the region.

Historically, locally-generated tsunamis have occurred in the Santa Barbara channel. In 1927 an earthquake offshore of Point Arguello produced run-up of 6 feet (1.8 m) at Surf, near Guadalupe (Lander, et al, 1993). In December 1812, historical accounts record several local earthquakes near Santa Barbara causing significant damage to structures, and were associated with tsunamis of several meters recorded in Gaviota, Santa Barbara and Ventura (McCulloch, 1985; Lander, et al, 1993). The December 1812 tsunami is believed to have resulted from a large submarine landslide offshore of Refugio Canyon which was triggered by those earthquakes. In 1930, an M 5.2 earthquake off of Redondo Beach may have triggered a landslide that generated unusually large waves (Legg, et al, 2004) or a local tsunami (Lander, et al, 1993) with a 6-foot (1.8-m) run-up resulting in serious damage and one fatality in Santa Monica. Recurrence intervals for local events will be similar to the recurrence intervals for large, offshore earthquakes, generally hundreds to thousands of years; or, in the case of large offshore landslides, on the order of hundreds of years (Legg, et al, 2003).

While the probability of the project site being impacted by a tsunami can be considered low due to their rare occurrence in the Santa Barbara area, it is not impossible for such an event to occur. Santa Barbara County (1979, 1991) suggests that a conservative contour elevation of 40 feet be established for the tsunami risk limit, but this is somewhat arbitrary and does not mean that a high level of destruction would necessarily result at that elevation. Areas below the 10-foot contour would be most susceptible to inundation and damage (Santa Barbara County, 1979, 1991). The California Geological Survey (CGS) also has published tsunami inundation maps for coastal California (CGS, 2009). A portion of the map covering the Santa Barbara area is provided on Plate 7 - Tsunami Inundation Map. The CGS (2009) map indicates that the site is located within the mapped tsunami inundation area.

3.6 EXPANSIVE SOIL

Expansive soils have the potential to swell when moisture content increases or shrink when moisture content decreases. Foundations, slabs-on-grade, and other structural components in contact with the onsite soils may be subjected to uplift forces due to swelling soils. On the basis of the data acquired for this study, the subsurface conditions in the foundation, on-grade floor slab and pavements and hardscape consist of silty sand and by inspection can be assumed to have a very low potential for expansion.

4.0 SURFACE WATER PERCOLATION TESTING AND EVALUATION

4.1.1 Hollow Stem-Auger Drill Holes

We excavated two hollow-stem-auger (HSA) drill holes to depths of approximately 3 and 4 feet below the ground surface (bgs) at locations P-01 and P-02, respectively. The drilling work was performed by S/G Drilling Company of Lompoc, California (S/G). S/G used a truck-



mounted CME-85 drill rig equipped with 8-inch-diameter hollow-stem-augers to excavate the drill holes. The two drill holes were excavated in existing paved parking stalls at the locations shown on Plate 2.

4.1.2 Percolation Testing

We performed the percolation tests using borehole percolation test procedures. After completing the drilling work, we placed several inches of drain rock at the bottom of the excavation, set a 2-inch diameter perforated polyvinyl-chloride (PVC) casing, and backfilled the annular space within the test interval with drain rock to prevent the sidewalls from caving during the test. The test wells were constructed through the hollow-stem-augers, and the augers were pulled slowly with the placement of annular backfill to prevent caving. We performed the tests over 2-foot depth intervals in each hole (1 to 3 feet at location P-01, and 2 to 4 feet at location P-02). Testing at each location consisted of a pre-soak and percolation test period. Each test was carried out utilizing a falling-head procedure in general accordance with the provisions outlined in the City of Santa Barbara's Storm Water BMP Guidance Manual [SBSWGM] (City of Santa Barbara, 2008).

Pre-Soak. After constructing the temporary percolation test wells, water was added through the casing to saturate the anticipated test intervals and allowed to percolate into the test holes over the weekend. Our personnel then filled the holes to the top of the test intervals and maintained the water level for at least 1 hour to saturate the soils prior to initiating the test. A one-hour period is typically considered sufficient in coarse grained conditions such as those encountered at the testing locations provided that a stabilized rate can be obtained during testing.

Percolation Measurements. After the pre-soak period, we refilled the casing with water to the top of the test interval and began the percolation tests. Once the initial water level was set, readings of the water surface level inside the casing were taken inside the casing using a tape measure at regular time intervals ranging from between 1 and 4 minutes (the actual time intervals were recorded with each reading).

Although readings are typically taken at 10 minute intervals during percolation testing, the measured rates were high and the time interval between readings needed to be reduced in order to collect the required data prior to refilling the holes for subsequent test runs. We considered one full test as either a full hour with readings at 10 minute intervals, or the time required for the water level reach the bottom of the cased portion of the test interval. After completion, the water levels were reset to the top of the test interval and the test was repeated four times.

After testing was complete, we removed the perforated PVC casing and left the drain rock in the hole. We backfilled the holes to the ground surface with drill hole cuttings and hand tamped the soil backfill reduce the potential for future settlement. We patched the pavement surface using black-dyed quick set concrete.



4.1.3 Findings

Earth Materials. At location P-01 in the easterly parking area drilling encountered approximately 6 inches of asphalt concrete overlying about 2 feet of silty sand fill material. Our staff noted what appeared to be native fine to medium-grained beach sand underlying the artificial fill. Drilling at location P-02 encountered approximately 2 feet of asphalt concrete and concrete pavements associated with the existing parking lot and the abandoned road that ran along the promenade parallel to the beach. At that exploration point the pavement section appeared to be directly underlain by native beach sand similar to that encountered at the bottom of the hole at location P-01.

Geotechnical conditions at depth can be extrapolated from our adjacent drill holes and CPT/SCPT soundings. Conditions encountered in those explorations consisted of the pavement structural section overlying silty sand and poorly graded sand to a depth of at least 10 feet.

Percolation Results. Table 5 summarizes the corrected and uncorrected results of the percolation testing program for this project. The corrected values represent the equivalent field percolation rate for an open, uncased, 12-inch diameter hole. The volume of water displaced by the annular backfill was determined by filling a 1000 mL graduated cylinder with drain rock and then adding water until all of the void space was filled. Our staff noted the volume of water required to saturate the void spaces and extrapolated the resulting void ratio to determine the corrected field percolation rates provided below.

Table 5. Field Percolation Test Results

Test Well ID Test Interval (feet bgs)

Stabilized Field Test Percolation Rate (in/hr)

Uncorrected (Field Data)

Corrected (Equiv. for open 12 hole)

P-01 1-3 46 9 1/2

P-02 2-4 137 29

The corrected percolation rates for the intervals tested are higher than 2.4 inches per hour (the threshold value that typically requires upstream runoff treatment [City of Santa Barbara, 2008]). The measured rates exceeded to threshold value. Calculations for the percolation rate evaluation are provided in Appendix F Percolation Test Calculations.

Infiltration BMPs relying upon some infiltration component to manage storm water flow should be set back from any structural foundation for buildings or other site structures (e.g., retaining walls) by 10 feet to reduce the potential for moisture intrusion. In addition, measures to maintain subgrade stability in pavement or hardscape areas (such as geogrid reinforcement or increased aggregate base thickness) will be required if infiltration is incorporated into the design of those elements.



Although the percolation rate measured at location P-01 was significantly slower than that at P-02, we expect that the deviation can be attributed in part to the fact that a majority of the test interval at location P-1 consisted of silty sand artificial fill materials rather than beach sand. It is also possible that during drilling and pre-soaking some of the silty soil from the artificial fill materials may have re-deposited into the bottom of the hole and reduced the percolation rate in the beach sand portion of the interval. In our opinion, it is reasonable to assume that the infiltration rate in the beach sand material at the bottom of test hole P-01 would be similar to that measured at location P-02. If the design of the proposed BMPs provides that the surface water runoff infiltrates directly into the beach sand material, in our opinion it is reasonable to use the higher rate determined from location P-02. The silty sand artificial fill material should be bypassed by the BMP or removed and replaced with beach sand deposits similar to those encountered at location P-02.

5.0 CONCLUSIONS AND RECOMMENDATIONS

5.1 SUMMARY OF FINDINGS

A summary of the main findings of our geotechnical evaluation follows.

The bathhouse structure is generally underlain by dense to very dense poorly graded sand (SP-SM) to silty sand (SM) interbedded with one to two fine-grain layers of stiff to very stiff clayey silt (ML) to lean clay (CL). Some thin sand seams are present in the fine-grained units. The fine-grain layers appear to occur at variable depths and generally range from about 5 feet thick up to about 20 feet thick;

A nominal thickness (less than a few feet thick) of artificial probably consisting of sand to silty sand is likely present below the first floor slab and foundations;

The near surface soils are granular and appear to have a relatively high percolation/infiltration rate. Measured percolation rates ranged from about 9 to 29 inches per hour (adjusted for an open, uncased 12-inch diameter hole).

We encountered groundwater at depths of about 7 to 8 feet (relative to the parking lot grades) and for our evaluations have assumed that groundwater is at el. +6 feet.

For the purposes of our analyses, we have assumed potential future sea level rese would result in a corresponding rise in the groundwater level. On the basis of our interpretation of the data in Moffatt & Nichol (2014) we have assumed a potential for a 3-foot rise in sea level in 2100 and a corresponding groundwater elevation of +9 feet.

No faults are shown on published geologic maps of the area crossing through or trending towards the site. The site is within a seismically active area and will likely be subjected to strong ground shaking during the life of the project. Seismic data for design of the retrofit and new construction are provided in this report.

The site is not considered subject to static slope instability or landsliding that would impact the site;



The potential for liquefaction at the site is considered to be low to very low under the current assumed groundwater conditions and the consequences of liquefaction are anticipated to consist of minor settlements of an inch or less. In addition, liquefaction-induced lateral spreading is not considered to be a significant hazard under the current assumed groundwater conditions.

Site retaining walls, trash enclosures, and other lightly loaded structures outside of the building can be supported on shallow foundations bearing on a layer of new compacted fill. Foundation design and grading recommendations are provided in this report.

Foundations for new shear walls can consist of grade beams and shallow continuous footings founded on the on-site soils and new compacted fill;

In the event the groundwater rises to about +9 feet from sea level rise (as assumed), our analyses indicate that the soils near the foundation level and between about el. +9 and about el. +6 could potentially liquefy during strong ground shaking. The potential consequences of liquefaction in this case could consist of a reduction in bearing capacity of existing and new shallow foundations and liquefaction-induced settlement. The impact to new pile supported shear wall grade beam foundations could consist of a small reduction in axial capacity, a softening of the soil in this zone and a commensurate reduction in the lateral resistance of the pile elements. Settlements from liquefaction occurring from coupled liquefaction and rise in groundwater level are estimated to be about an inch. This settlement would be in addition to the estimated liquefaction settlement that could occur under the current groundwater conditions.

The potential for liquefaction occurring at a relatively shallow depth under the coupled sea level rise and liquefaction condition has the potential for result in liquefaction-triggered lateral spreading. On a qualitative basis, we estimate that lateral deformations could possible range from a few inches to about a foot for the sea level rise scenarios of 2.9 and 3.1 feet.

5.2 INTRODUCTION

The conclusions and recommendations presented in this report are based on our understanding of the project and discussions with the project team, review of the referenced information, field exploration, laboratory testing, and geotechnical analyses.

Currently, we anticipate that the Cabrillo Pavilion structure will be seismically retrofitted and renovated. New shear wall foundations will be required and are expected to consist of new pile-supported foundations/grade beams. Initially the structural engineer had considered using helical piles or micro piles for supporting the new grade beams. However, we understand those elements are not being considered at this time.

Specific conclusions and recommendations are provided below to address general earthwork and grading for the project site, design for new foundations and site retaining walls, and new pavements under the current estimated groundwater conditions. Consequences of



potential sea level rise are evaluated on a qualitative basis but have not been considered in our general recommendations provided below. A discussion of the potential consequences of a rise in groundwater from sea level rise and potential liquefaction is provided in Section 5.12.

5.3 GENERAL EARTHWORK AND GRADING

5.3.1 Site Preparation

Site preparation for the project site will require removal of pavement sections, curbs, landscaping and organic matter, unsuitable fill materials, construction debris, or other deleterious materials. Those materials should be removed and wasted from construction areas. Abandoned underground structures such as irrigation systems, wells, pipelines, utility conduits, old foundations, etc., should be removed or treated in a manner prescribed by the controlling governmental agencies. Excavations required for the removal of such facilities that extend below the planned remedial grading limits (e.g. overexcavation depth) should be observed by Fugro staff prior to backfilling.

5.3.2 Excavation Considerations

We anticipate that excavations for the proposed new building foundations will be located at a depth of about 3 to 5 feet below the existing floor slab level. New foundations for site walls and the trash enclosure will likely be located at a depth of about 2 to 3 feet below finish grade. We estimate that excavations for the proposed foundations will be less than about 5 feet deep, relative to the existing or final grade.

As described on the drill hole logs (Appendix A), our explorations generally encountered medium dense to dense silty sand and poorly graded sand with siltvery stiff sandy silt within the anticipated excavation or grading limits for the project. At the time of our field work, groundwater was measured at a depth of about 7 to 9 feet bgs, relative to the existing parking lot grade. Based on the measured depth to water and the site elevation data provided to us, we estimate the groundwater elevation at the time of our study to be at about el. +6 feet. In our opinion, excavations for project can be performed using conventional heavy-duty earth excavation equipment in good working order. Excavations should be properly dewatered and free of groundwater seepage. We note that the soils are granular with little to no cohesion and caving or sloughing of excavation sidewalls should also be anticipated.

5.3.3 Remedial Grading and Overexcavation

New Shear Wall Foundations. We anticipate that new shear wall footings and grade beams will be supported on in-place medium dense silty sand to poorly graded sand with silt located below the existing floor slab level. Dewatering to control groundwater, if required, should be performed in advance of the excavation work and verified by potholing or by installing monitoring devices.

We anticipate the excavations for the new shear wall pile-supported foundations/grade beams will be constructed with temporary sloped excavations that are appropriately dewatered



(free from water seepage) and the base of the excavation. We anticipate that the excavations will need to extend about 2 feet beyond the foundations and that the concrete for the new foundations would require formwork. Remedial site grading for new foundations should consist of excavating and removing the existing soils to a depth of 1-foot below the bottom of the proposed foundation elements. The excavated subgrade should be protected and stabilized soon after reaching the desired grade to protect the foundation support materials from disturbance or softening. To protect the exposed subgrade and provide a working surface for construction, we recommend that at least 1 foot of aggregate base be placed in the foundation excavation bottom prior to constructing the foundations.

Site Walls and Minor Structures. Site preparation and grading for minor structures and site walls supported on shallow foundations should be performed to remove existing artificial fill and other unsuitable soils and provide support and lateral resistance for the proposed shallow foundations. We recommend remedial site grading for site wall foundations and minor structures supported on shallow foundations should consist of excavating and removing the existing soils to a depth of at least 2 feet below the existing ground surface or to a depth 1 foot below the proposed foundation subgrade level, whichever results in the larger excavation depth. The excavations should be deepened as necessary to remove existing fill or soft or unsuitable alluvial soils and should extend at least 3 feet beyond the proposed foundation. Where limited by property lines or other constraints, the remedial grading should extend to the property line and be cut vertical or near vertical. Slot cutting adjacent to the property line should be performed where sloughing of the excavation slope could impact existing infrastructure.

Parking and Exterior Slab Areas. Overexcavation for parking areas and exterior slab on grade should extend a minimum 12 inches below the existing grade or 1 foot below the bottom of the proposed pavement section, whichever is deeper. Overexcavation should extend laterally at least 3 feet beyond the proposed parking lot limits or exterior slabs on grade. The excavation should be deepened, if needed, to remove existing unsuitable fill or other deleterious soils/materials.

5.3.4 Subgrade Preparation

Overexcavation subgrade in building, pavement, exterior slab-on-grade areas, and in areas to receive fill should be cut neat and observed by a representative of Fugro prior to processing the subgrade or placing fill materials. If soft or loose, compressible, organic, or otherwise deleterious soils are present at the subgrade level, the overexcavation may need to be deepened to remove those soils. The presence of loose or compressible materials can be evaluated visually by using a hand probe or by proof rolling. Provisions for deepening the excavation and soil removal should be included in the project plans and specifications.

After Fugro personnel approve the subgrade conditions, the excavation bottom should be scarified to a minimum depth of 8 inches, moisture conditioned to within 2 percent above optimum, and compacted to at least 90 percent relative compaction. We note that scarifying and recompaction of the excavation subgrade for new interior building foundations and grade



beams is not required. However, as noted, we recommend that a layer of aggregate base be placed on the excavated subgrade and compacted to provide an improved working surface.

Roots or organics observed during the scarifying work should be removed prior to compaction. Compacted fill can be placed to finished grade after the completion of the recommended overexcavation. Where unsuitable or pumping subgrade is encountered, stabilization measures will be required prior to the placement of overlying fill. Suggested measures to improve unstable subgrade conditions are outlined below.

5.3.5 Special Subgrade Stabilization Measures

Special stabilization measures may be required if aeration does not appear to be effective in mitigating soft or pumping subgrade. These measures may be required to provide a firm and unyielding subgrade surface. Special subgrade stabilization measures that have successfully been used in the Santa Barbara/Goleta area previously consist of:

Excavation and removal of a limited depth of soil and replacement with float rock (crushed stone) and geogrid reinforcement such as Tensar BX1100 or equivalent and filter fabric,

Stabilization with 3 to 6 percent cement;

Construction of a mud mat using 2-sack sand cement slurry or lean concrete, or

Removing and replacing the unstable subgrade with compacted fill (where possible).

Whether those measures are required or not will depend on the moisture content of the subgrade materials and the nature of the construction activities (e.g., vibratory compaction equipment, equipment wheel loads, number of equipment passes, etc.).

Such special measures suggested herein should be considered if soft or pumping subgrade becomes a nuisance during construction. We suggest that contract documents include contingency items for stabilizing pumping subgrade and possible procurement of geosynthetics and rock or for cement treatment. The contractor, with input from the owner and engineer, should select the method of subgrade stabilization used for the project. The actual method used may require some degree of trial and error by the contractor.

5.3.6 Fill Selection, Placement, and Compaction

All fill materials, onsite or imported, should be free from organic material, hazardous substances, unsuitable fill debris, and any other deleterious materials. Rock fragments or poorly weathered material less than 3 inches in diameter may be utilized in fill materials, provided those materials are not placed in concentrated pockets. The fill material should not contain rocks, blocky material, or lumps over 3 inches in maximum dimension, or more than 15 percent material larger than 2 inches in maximum dimension. Fill soils should be thoroughly mixed and blended prior to use as compacted fill.



Fill materials should be placed in layers that, when compacted, should not exceed 8 inches in compacted thickness. Each layer should be spread evenly, moisture-conditioned to about 2 percent above optimum, and processed and compacted to obtain a uniformly dense layer. The fill should be placed and compacted on near-horizontal planes to a minimum of 90 percent of the relative maximum dry density as determined in the laboratory by ASTM D1557.

Based on our explorations, onsite granular soils are considered suitable for structure fill and backfill.

5.4 DESIGN INPUT FOR NEW NON-RETROFIT SHALLOW FOUNDATIONS

On the basis of discussions with Greg Storke of Storke and Wolfe Structural Engineers (project Structural Engineer) we understand that new retrofit shear wall foundations are anticipated to consist of new grade beams supported on cast-in-drill hole (CIDH) concrete piles. We understand that this is currently the preferred option for supporting the new shear walls. As noted previously, helical anchors and micro piles were initially considered for the project. However, we understand that those elements are currently not being considered.

Geotechnical input for new, retrofit CIDH piles are provided below. We have assumed that the new grade beams will not derive support from the underlying soils. However, the grade beams will provide resistance to lateral loading from passive soil pressure.

5.4.1 Cast-In Drill Hole Piles

We have assumed that the pile caps will rest at approximately el. +11 feet or about 3 feet below the adjacent grade. For this project, we have assumed the CIDH piles will be at least 18 inches in diameter and have performed analyses for a typical 18-inch, 24-inch, and 30-inch diameter.

5.4.2 Axial Capacity

We estimated the axial capacity of CIDH piles for the project using the computer program SHAFT6 (Ensoft, 2010). Our analysis incorporated the procedures described in FHWA (2010). We evaluated the axial capacity of the three selected pile diameters (18, 24, and 20 inch diameter) for the idealized soil profile discussed above. The estimated ultimate axial capacities of the assumed typical piles are plotted graphically as a function of pile embedment depth in Appendix G Axial Capacity of CIDH Piles. The plots of ultimate axial capacities provided in Appendix G do not incorporate a factor of safety and are assumed to generally represent average conditions. Computations for upper and low bound conditions/capactities were not performed for this study.

Because the CIDH piles will be constructed below the water table, we anticipate that the contractor will likely have difficulty preventing loose material from collecting at the bottoms of the drilled holes. Therefore, we neglected the potential contribution from end bearing in the estimated axial compression capacity of the piles.



Drilled shaft foundations should be embedded at least 25 to 30 feet into the medium dense to very dense sand deposits. In an effort to reduce the potential for interaction between adjacent piers (from an axial capacity standpoint), we recommend that the CIDH piles be spaced no closer than 3 shaft diameters on-center. We note that a wider pile spacing, (about 5 pile diameters) would be required to avoid group affects from lateral loading.

5.4.3 Uplift Resistance

Drilled shaft foundations can be designed to support vertical loads acting in compression or tension. The ult

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