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CITY OF SAN
o File NO.Q.50 .1?;"f}/'
BERNARDINO - REQUEST FOR COUNCIL ACTION
From: ROGER G. HARDGRAVE REC'D.-AOlJ(lib~i.. Adoption of Procedures. and
Guidelines -- Liquefaction
Dept: Public Works/Engineering IsaS JUl \8 ~.M 'I): 05 Investigations and Reports
Date: 7-14-89
Synopsis of Previous Council action:
08-16-82 -- Resolution No. 82-345 adopted to establish procedures
and guidelines for evaluating the hazard of liquefac-
tion of soils.
03-23-89 -- Legislative Review Conunittee reviewed proposed pro-
cedures and guidelines for evaluating liquefaction
potential. Concern was expressed over reference to
Water Department maps. Item continued.
07-17-89 -- First reading of Ordinance creating Section 15.08 of
San Bernardino Municipal Code Liquefaction
Potential, conducted.
Recommended motion:
Adopt resolution.
cc: Marshall Julian
Jim Richardson
Jim Penman
~Brad Kilger
Herb Wessel
Larry Reed
Contact person: Gene R. Klatt
Staff Report &
Supporting data attached: Resolution
Phone:
')12')
Ward:
All
FUNDING REQUIREMENTS:
Amount: N / A
Source: (Acct. No.)
(Acct, Description)
Finance:
Council Notes:
75-0262
Agenda Item NO'~~
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ciTY OF SAN BERARDINO - REQUEST lOR COUNCIL ACTION
STAFF REPORT
Concurrently, with the second reading of the Ordinance
on Liquefaction, adoption of the attached resolution will set
forth the guidelines for the preparation of the required reports
and the contents of the reports.
In meetings with Planning, Building and Safety, Water
Department, City Attorney's Office, Consulting Soils Engineers
and others, it was determined that a guideline .for the
preparation of reports would be useful and necessary to insure
adequate compliance with the adopted ordinance.
After much discussion and consideration, agreement was
reached on the content, format and submittal process for such
reports. The attached resolution sets forth these requirements.
Staff recommends the adoption of the attached resolution
adopting procedures and guidelines for liquefaction reports.
7-14-89
75-0264
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RESOLUTION NO.
2
RESOLUTION OF THE CITY OF SAN BERNARDINO ADOPTING
3 PROCEDURES AND GUIDELINES FOR LIQUEFACTION INVESTIGATIONS AND
REPORTS REQUIRED BY CHAPTER 15.08 OF THE SAN BERNARDINO MUNICIPAL
4 CODE; AND RESCINDING RESOLUTION NO. 82-345.
5 BE IT RESOLVED BY THE MAYOR AND COMMON COUNCIL OF THE CITY
OF SAN BERNARDINO AS FOLLOWS:
6
SECTION 1. Administrative Procedures/Guidelines for
7 Liquefaction Investigations and Reports.
8
In accordance with Chapter 15.08 of San Bernardino
10 established the following procedures/guidelines for liquefaction
9
Municipal Code.
The Director of Public Works/City Engineer has
11 investigations and reports.
SECTION 2. The Investigation.
12
13
The investigation shall be designed and
A.
Purpose.
14
carried out to determine the potential for liquefaction.
For
15 complex, essential structures, the investigation shall be as
16
thorough as cUrrent technology will permit.
Investigations may
17 also require the expertise of a registered geologist, or
18 registered engineering geologist, since both geologic/seismic
19 elements and quantitative materials testing will be involved.
20
Site investigation.
B.
21
Seismic factors.
The history of earthquake
1.
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activity and recurrence intervals of damaging earthquakes
23
shall be discussed.
A design earthquake shall be
24
postulated, with a best estimate of the fOllowing
characteristics as they will be experienced at the site:
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Richter magnitude.
a.
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Maximum Probable Rock Acceleration from
b.
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July 10, 1989
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various faults, (as shown in the Seismic Element
of the General P1ari) that produces the highest
value.
c.
Time (duration) of strong shaking.
d.
Dominant frequencies of seismic spectra.
e.
In no case shall the rock acceleration be
less than the amount indicated on the map in the
Seismic Element of the General Plan entitled:
'Maximum Credible Rock Acceleration from
Earthquakes. '
2. Hydrologic conditions.
The historical record of
12 depths to the ground water table (or saturated conditions) shall
13
The depth to
be determined for the site from City records.
14 ground water used in the analysis, as determined by borings,
15 shall be stated, but design will be based on a level no less than
17
16 .ten (10) feet.
Borings shall be used to
18
3. Subsurface Investigation.
They should
determine the necessary subsurface information.
19 extend to a minimum depth of fifty (50) feet and be spaced across
20 the site so that significant variations in subsurface conditions
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will be defined.
22 be:
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a.
b.
Examples of significant subsurface data would
drilling rate,
from surface ASTM No. D 1586-67,
standard penetration test at every five (5) feet
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July 10, 1989
c.
d.
classification, definition, and depth of soils,
general stratigraphy.
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For essential projects, more subsurface information
2 utilizing pits, trenches and geophysical investigations may be
3
They allow direct observation of the undisturbed
necessary.
4 vertical section so that evidence of liquefaction such as sand
5 boils, sand dikes, or chaotic disturbance of the soil or sediment
6 can be viewed. Also, horizontal and vertical permeability can be
7 better estimated from a view of the undisturbed layering.
8 Furthermore, the ancient sedimentary environment of the site can
9 be interpreted from the trench of pit walls.
4.
11 techniques may be useful to define the ground water table, but
Geophysical Investigation.
Refraction seismic
12 this indirect method should only be used to confirm or extend
14
13 downhole or trench data.
15 The report may be simple or comprehensive, depending upon
SECTION 3. The Report.
16 the vulnerability of the site to liquefaction and the kinds of
17 buildings or other structures to be built. The following topics
18 should be considered and included if pertinent.
19
A. Text
20
1.
Site location relative to established property
21
boundaries.
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2.
City reference number (CUP, ROP, Tract No., etc.)
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3.
Purpose and scope of investigation.
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4.
Design earthquake parameters (discussed above).
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5.
Description of kind and location of proposed
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construction.
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6.
Procedures and techniques used in the
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July 10, 1989
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investigation.
Detailed description of subsurface conditions and
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results of quantitative testing.
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B. Conclusions and Recommendations.
1.
Identify the location and distribution of areas
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vulnerable to liquefaction and estimate the depth of
zones of possible failure due to liquefaction.
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2.
Identify critical parameters of the design
earthquake:
fault, magnitude, accelerations,
duration, frequency, etc.
3.
Identify procedures for reducing hazard of
liquefaction.
a.
geotechnical.
b. structural.
C. Documentation of Report.
Include index map showing location of site.
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July 10, 1989
1.
2.
Include site plan which shall display:
a.
topography (if available);
b.
proposed building location;
c.
locations of borings, wells, trenches;
d.
surface geological features.
3.
Include logs of borings (with blow counts), wells
trenches.
4.
Include sample descriptions and locations.
5.
Include sample analysis and tests, based upon the
penetration analysis developed by Dr. Bolton Seed, or
other approved method.
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Include graphs and charts, as needed to
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demonstrate liquefaction potential.
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7.
Include description of analytical techniques
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used.
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8.
Include signatures and license numbers of
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Registered Civil Engineers responsible for the report,
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and any Registered Geologists that assisted in the
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preparation.
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9. Include a list of references utilized in report.
10. List final recommendations with references to
conclusions.
SECTION 4. Submittal.
13 Two copies of the required Liquefaction Report and
14 Mitigation Measures shall be submitted to the Director of Public
15 Works/City Engineer and approved prior to issuance of grading and
16
building permits.
If the Liquefaction Report and Mitigation
17 Measures are approved by the Director of Public Works/City
18 Engineer, a copy will be forwarded to the Director of Building
19
and Safety for reference in checking structural plans.
The.
20 structural plans shall contain a statement that the building has
21 been designed in accordance with the Mi tigat10n Measures
22 contained in the Liquefaction Report.
23
If the Liquefaction Report and Mitigation Measures
24 submitted to the Director of Public Works/City Engineer are
25 determined to be unacceptable, the interested party may appeal
26
this decision to the Mayor and Council.
No permits will be
27 issued prior to approval by the Director of Public Works/City
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1 Engineer or prior to an appeals decision by the Mayor and Common
2 Council approving the Liquefaction Report and Mitigation
3 Measures.
4 I HEREBY CERTIFY that the foregoing resolution was duly
5 adopted by the Mayor and Common Council of the City of San
6 Bernardino at a meeting thereof, held on the
7 day of , 1989, by the following vote, to wit:
8 AYES: Council Members
9
NAYS:
ABSENT:
13
City Clerk
14
The foregoing resolution is hereby approved this
day
15
of
, 1989.
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W. R. Holcomb, Mayor
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Approved as to
form and legal content:
21
JAMES F. PENMAN,
City Attorney
^
By: ~>uo -; A~.~
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