JUST EXACTLY WHAT DOES CGS LOOK FOR WHEN REVIEWING SCHOOL AND HOSPITAL REPORTS

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JUST EXACTLY WHAT DOES CGS LOOK FOR WHEN
REVIEWING SCHOOL AND HOSPITAL REPORTS?
Anne Rosinski, CEGSenior Engineering
GeologistCalifornia Geological Survey, Menlo
Park
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OVERVIEW

• Overview of review process

• References

• Describe what CGS looks for in a report

• NOT comment on the engineering

• NOT tell you how to do your job

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CALIFORNIA CODES AND REGULATIONS

• Alquist-Priolo Earthquake Fault Zoning Act
  Public Resources Code --- for active faults
• California Seismic Hazard Mapping Act
  Public Resources Code --- for liquefaction
  landslides
• 2007 California Building Standards Administrative
  Code(enabling agencies, occupancy, etc.) CCR
  Title 24, Part 1 --- specific rules for
  California agencies
• 2007 California Building Code, especially
  Chapters 16, 18, 33 CCR Title 24, Part 2
  ---upgraded for California
• California Education Code CCR Title 5,
  Campuses for Public Schools Community Colleges
  (early in site selection)

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USEFUL REFERENCES

• Will need copies of both 2007 CBC and ASCE 7-05

• Landslide inventory maps from Zone Maps
• http//www.consrv.ca.gov/cgs

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USEFUL REFERENCES
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IMPORTANT PUBLICATION FROM CGS AND SCEC
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USEFUL REFERENCES

• Latitude Longitude
• on-line easily looked-up (no more measuring and
• calculating lat./long for decimal degree input
  into PSHA)

• Alquist-Priolo Fault Zone Maps CD ROM pdf
• from CGS

• Liquefaction and Landslide Zone Maps and
• Reports on-line pdf from CGS

• USGS website for ground motion parameters
• http//earthquake.usgs.gov/research/hazmaps/design
  /

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USEFUL REFERENCES

• PEER website for Next Generation Attenuation
• Relationships
• http//peer.berkeley.edu/products/rep_nga_models
  .html

• As of 9/12/07 the following relationships have
  been
• finalized
• Boore Atkinson (7/02/07)
• Campbell Bozorgnia (7/19/07)

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YES
NO
Two Copies of Geologic Hazards Report Required
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CGS NOTE 48
GUIDANCE REGARDING TOPICS CGS IS LOOKING FOR.
NOT A LIST OF REQUIREMENTS
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NOTE 48 CHECKLIST

• Used by consulting geotechnical firms to
  ascertain completeness
• of their engineering geology reports.

• Uniformly used by the Engineering Geologists
  within the California Geological Survey.

• All consulting geotechnical firms are judged to
  the same statewide level of review at 4 DSA
  regional offices 2 OSHPD offices.

• Concise 2-page checklist format provides
  comprehensive overview
• for the entire process ---- insights for
  owners/architects for
• scoping of contract.

• Citations to specific Code sections of CCR Title
  24, CBC and ASCE 7-05

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ANATOMY OF NOTE 48

• Project Location

• Engineering Geology / Site Characterization

• Seismology Calculation of Earthquake
• Ground Motion

• Liquefaction / Seismic Settlement Analysis

• Slope Stability Analysis

• Other Geologic Hazards or Adverse Site
• Conditions

• Report Documentation

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PROJECT LOCATION

• Item 1 Site Location Map, Street Address,
• County Name

• Item 2. Plot Plan with Exploration Data
• with Building Footprint
• 1 boring or exploration shaft per 5000 ft2

• Item 3. Site Coordinates
• Latitude and Longitude

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ENGINEERING GEOLOGY

• Item 4. Regional Geology and Regional
• Fault Maps

• Item 5. Geologic Map of Site
• Large-scale geologic map with proper symbols and
  geologic legend (stratigraphic name, age,
  lithologic description).

• Item 6. Subsurface Geology

• Item 7. Geologic Cross Sections

• Item 8. Active Faulting Coseismic
• Deformation Across Site

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HOLOCENE ACTIVE FAULTS
Public Schools and Hospitals must be Set-Back 50
feet from Active Faults Fault Trenching Must be
Performed by a Certified Engineering Geologist
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ENGINEERING GEOLOGY

• Item 9. Geologic Hazard Zones (Liquefaction
  Landslides)
• Prepare page-sized extract map of Liquefaction
  and Landslide zones (state and local)

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REGULATORY ZONE MAPS
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SEISMIC HAZARD ZONING INDEX MAP
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ENGINEERING GEOLOGY

• Item 10. Geotechnical Testing of
• Representative Samples

• Item 11. Geologic Consideration of Grading
• Plans and Foundation Plans

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SEISMOLOGY

• Item 12. Evaluation of Historical Seismicity
• Short description of how historical earthquakes
  have
• affected the site not a list of earthquakes.

• Item 13. Mapped Spectral Acceleration
• Parameters
• Ss and S1
• http//earthquake.usgs.gov/research/hazmaps/desi
  gn

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SEISMOLOGY

• Run Java program from USGS website

• Select analysis option ASCE 7 Standard 2007 CBC

• Select site location Latitude/Longitude option

• Calculate Ss, S1, Fa, Fv, SM, SD
• Default Site Class B modify as necessary

• View Spectra
• Select Design Spectrum Sa vs. T

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SEISMOLOGY

• Item 14. Classify Geologic Subgrade

• Item 15. Site Coefficients and Adjusted MCE
• Spectral Response Acceleration Parameters
• Fa, Fv, and SMS, SM1
• From USGS website

• Item 16. Design Spectral Acceleration
• Parameters
• SDS and SD1
• From USGS website

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DESIGN GROUND MOTION

• Determine S1 and SS from USGS website
• http//earthquake.usgs.gov/research/hazmaps/desig
  n

• Determine site classification

• Use tables to determine site coefficients
• http//earthquake.usgs.gov/research/hazmaps/desi
  gn

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DESIGN GROUND MOTION

• Calculate adjusted MCE spectral response
• acceleration parameters (adjusted for site
  effects)
• http//earthquake.usgs.gov/research/hazmaps/desig
  n
• Default site class for USGS site is Site Class B
• Short Period (0.2 sec) SMS FaSS
• Long Period (1.0 sec) SM1 FvS1

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DESIGN GROUND MOTION

• Calculate design spectral acceleration
  parameters
• http//earthquake.usgs.gov/research/hazmaps/desi
  gn
• Short Period (0.2 sec) SDS 2/3 SMS
• Long Period (1.0 sec) SD1 2/3 SM1

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SEISMOLOGY

• Item 17. Seismic Design Category
• Report if S1 gt 0.75

• Item 18. Deaggregated Seismic Source
• Parameters
• Modal Magnitude (Mw) and Modal Distance (km) to
  fault

• Item 19. Site-Specific Ground Motion Analysis
• For sites within 10km of active fault
• Provide Probabilistic MCE, Deterministic MCE, and
  Deterministic Lower Limit and Design Response
  Spectra

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SITE-SPECIFIC GROUND MOTION

• Calculate MCE

• As of July 20, 2007 CGS will allow use of FINAL
  published versions of Boore Atkinson (7/2/07)
  and Campbell Bozorgnia (7/19/07) NGAs.

• Projects that use earlier published versions
• of the aforementioned NGAs or NGAs from
• other authors that have not been finalized
• will not be allowed.

• The consultant should describe their rationale
• for input parameters and the average of two
• is preferable to selecting one relationship.

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CALCULATE MCE USING BOTH DETERMINISTIC and
PROBABILISTIC METHODS
Probabilistic method
Probabilistic method 5 damped Acceleration
response spectrum with 2 in 50 years
probability of exceedance (MCE)
Calculate 2/3 of this MCE value Site Specific
Design Spectral Response Acceleration where Sa
2/3 S aM
Choose the lesser of these two values
Site-Specific MCE
Deterministic method
Calculate 150 of largest median 5 damped
deterministic spectral response acceleration
Cannot be less than 80 of General Response
Spectrum
Choose the greater of these 2 values
Calculate deterministic lower limit SaM 1.5
Fa SaM 0.6 Fv/T
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SITE-SPECIFIC DESIGN ACCELERATION PARAMETERS
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SEISMOLOGY

• Item 20. Time Histories of Earthquake
• Ground Motion
• Compute target spectra, justify selected
  earthquake
• records, scale to target, and show initial and
  scaled
• records.

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LIQUEFACTION

• Item 21. Geologic Setting for Occurrence of
  Seismically-Induced Liquefaction
• Groundwater lt50 ft. depth use historical high
  for calculations
• Low-density, non-plastic fines, typically SPT
  (N1)60lt 30

• Item 22. Liquefaction Calculations
• Provide all input parameters (no estimates)
• Evaluate with Peak Ground Acceleration based on
• site-specific study or Peak Ground Acceleration
  SDS/2.5

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LIQUEFACTION

• Item 23. Seismic Settlement of Entire Soil
• Column
• For 2 or more locations within site
• Evaluate both saturated and unsaturated layers of
  the
• entire soil column
• Provide calculations including all input
  parameters (no
• estimates)

• Item 24. Potential for Lateral Spreading
• Not just areas near a free-face

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PAST OCCURRENCES OF LIQUEFACTION
1989
1906
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LIQUEFACTION

• Item 25. Mitigation Options for Liquefaction
• Discuss effectiveness of options to mitigate
  liquefaction
• effects
• Acceptance criteria for ground-improvement schemes

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REMEDIATION METHODS
Mat foundation
Deep soil mixing
Injection grouting
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SLOPE STABILITY

• Item 26. Landslide Mapping
• Characterize potential for landsliding both on
  and off-site affecting proposed project

• Item 27. Determination of Static and Dynamic
• Strength Parameters
• Conduct appropriate laboratory tests to determine
  material
• strength for both static and dynamic conditions

• Item 28. Determination of Pseudo-Static
• Coefficient
• Recommended procedure available from
  http//www.scec.org/resources/catalog/hazardmitiga
  tion.html

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SLOPE STABILITY

• Item 29. Identify Critical Slip Surfaces for
• Static and Dynamic Analyses
• Failure surfaces should be modeled to include
  existing slip
• surfaces, discontinuities, geologic structure,
  and
• stratigraphy include appropriate ground water
  conditions

• Item 30. Dynamic Site Conditions
• Site response analysis and topographic effects
  should be
• considered if appropriate

• Item 31. Mitigation Options for Landsliding/
• Other Slope Failure

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OTHER GEOLOGIC HAZARDSOR ADVERSE SITE CONDITIONS

• Item 32. Expansive Soils

• Item 33. Corrosive/Reactive Geochemistry
• of Geologic Subgrade
• Soluable sulfates and corrosive soils

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OTHER GEOLOGIC HAZARDSOR ADVERSE SITE CONDITIONS

• Item 34. Conditional Geologic Assessment
• Hazardous materials methane, tar seeps
• Volcanic Eruption
• Flooding FEMA FIRM maps 100-year flood, levees
• Tsunami and seiche inundation
• Radon-222 gas
• Naturally occurring asbestos
• Hydrocollapse
• Regional subsidence
• Clays and cyclic softening

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REPORT DOCUMENTATION

• Item 35. Geology, Seismology and
• Geotechnical References

• Item 36. Certified Engineering Geologist

• Item 37. Registered Geotechnical Engineer

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FINAL REPORT APPROVAL

• All Important Topics Addressed

• Documentation to Support Conclusions

• Mitigation Recommendations for Hazards

• Prepared and Signed by RGE and CEG

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Begin with the End in Mind Subsurface
Strategy
WORK BACKWARDS THROUGH THESE PARAMETERS

• Ultimate Question What is Total Seismic
• Settlement? Differential Settlement?
• Total Settlement?

• Geologic Cross Section Through Foundation

• Adequate Subsurface Data Frequent sampling in
  sands

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• Adequate Depth and Number of Boreholes
• 50 feet deep for evaluating liquefaction,
• deeper if necessary within building footprint

• Visualize geologic subgrade anticipate
• complex stratigraphy

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Bright Forecast for CaliforniaPublic
Schools Hospitals

• Geotechnical Consultants have better access to
  new Seismic Hazard Zone Maps, new Metadata
  Digital Mapping for Earthquake Ground-Motion
  Geologic Hazards
• Action Begins with Knowing Where the Problems Are
• CCR Title 24, Calif. Bldg. Code custom code
  for California hazards
• Statewide Uniformity of Reviews using Note 48
  Checklist by the California Geological Survey
• Result Improved EarthquakeResilient
  ConstructionWhere it is Needed Most in California

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Anne Rosinski California Geological Survey 345
Middlefield Road, MS 520 Menlo Park, CA
94025 Anne.Rosinski_at_conservation.ca.gov 650.688.63
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Jennifer Thornburg California Geological
Survey 801 K. Street MS 12-32 Sacramento, CA
95814-3531 Jennifer.Thornburg_at_conservation.ca.gov
916.445.5488