HomeMy WebLinkAbout61-Public Works
~
LIJ
-
... ,lIJl
- REQU4TeFOR6COuNCIL~~ON
CII:f. OF SAN BERNARDIa,
.
From:
ROGER
G. HARDGRAVE REe'D.-ADMi!P.uont:
lOfr9 F.
Works/Engineerin~ Jul J J PJf 3: 05
Revision of Procedures and
Guidelines for Evaluating
Liquefaction Potential
Dept:
Public
Date: 7-07-89
Synopsis of Previous Council action:
08-16-82 -- Resolution No. 82-345 adopted to establish procedures
and guidelines for evaluating the hazard of lique-
faction of soils.
03-23-89 -- Legislative Review Committee reviewed proposed pro-
cedures and guidelines for evaluating liquefaction
potential. Concern was expressed over reference to
Water Department maps. Item continued.
Recommended motion:
Waive further reading of ordinance and layover final adoption.
~: arshall Julian
im Richardson
Jim Penman
Brad Kilger
Herb Wessel
Supporting data attached:
Roger G. Hardqrave
Staff Report &
Ordinance
Phone:
'in?'i
Contact person:
Ward:
All
FUNDING REQUIREMENTS:
Amount:
N/A
Source: (Acct. No.)
(Acct. DescriDtionl
Finance:
Council Notes:
75.0262
Agenda Item No
t-' I
-
~
-
.
. CI"IOOF SAN BERNARDICb - REQUOT FOR COUNCIL ACOoN
STAFF REPORT
Page 1 of 3
Resolution No. 82-345 was adopted to establish procedures
and guidelines for evaluating the liquefaction potential of sites
proposed for development. Under these guidelines, a Liquefaction
Report was required for all developments wi thin high or extreme
liquefaction potential zones. No exemptions were allowed for
small structures, except for R-1 and R-2 zones, and additions, or
in areas where previous reports had clearly demonstrated that
liquefaction would occur.
These procedures and guidelines failed to require that
Liquefaction Reports be signed by a Registered Civil Engineer,
who would assume responsibility. Reports were required wi thin
the artesian pressure zone boundary, as depicted on the map based
upon information provided by the Water Department on approximate
water table depths.
A report on liquefaction potential in the East Valley
Area was prepared by two employees of the U.S. Geological
Survey - Carson & Matti. This report was based upon some very
general assumptions, and showed an area of potential liquefaction
many times larger than the original map prepared by the Water
Department.
One of the conditions imposed by the moratorium from OPR
was that Liquefaction Reports be required for developments within
the area shown in the Carson - Matti report. This has resulted
in a tremendous increase in the number of reports required. Now
that the moratorium has been rescinded, we now have the ability
to designate a reasonable reference for determining liquefaction
potential.
There has long been a realization among the professionals
in the development industry that the original resolution was
unduly restrictive, and needed to be revised. A meeting was held
on 1-13-89 with the Planning Department, Building and Safety
Department, City Attorney's Office, City's consulting geologists,
soils engineers, and other affected parties.
During this meeting, consensus was reached on several re-
visions, the principal ones being:
1. Reports signed by Registered Civil Engineer.
2. Area of potential liquefaction should be based upon the map
in the new General Plan showing areas of liquefaction sus-
ceptibility, instead of the Carson - Matti Report.
07-07-89
75-0264
-
15
-
CI"IO OF SAN BERNARDIQ) - REQUQT FOR COUNCIL AcQON
.
STAFF REPORT
Page 2 of 3
3. Reports be submitted to the Director of Public Works/City
Engineer.
4. Exemptions should be allowed for certain structures.
5. Reports include mitigation measures.
Items for which consensus was not reached at this meeting were:
1. Should an applicant for a non-essential building be allowed
to assume that liquefaction will occur and design
accordingly.
2. Reports to be submitted prior to issuance of grading and
building permits.
Having the reports signed by a Registered Civil Engineer
will insure that the professional in charge will assume
responsibili ty. Inclusion of the mitigation measures in the
report will allow them to be reviewed in conjunction with
building plans, which will facilitate processing.
Many large agencies, such as the Cities of Los Angeles
and San Diego, allow exemptions of certain non-essential
buildings. These exemptions are based upon the Uniform Building
Code, which recognizes occupancy as a threshold in determining
assembly use. In no case would an essential structure (hospital,
police station, fire station, etc.) be exempted.
There are areas where previous
demonstrated that liquefaction will occur.
will allow applicants in these areas to
liquefy, and design accordingly.
reports have clearly
The proposed revision
assume the site will
A clause has been included in
reports only for the construction of new
modifications in excess of 25%.
Section 3 to require
buildings or structural
The threshold for buildings where the primary occupancy
is for assembly use, was revised from 300 to 50. This revision
will result in reports being required for retail developments in
excess of 1,500 sq. feet and office developments in excess of
5,000 square feet.
Reports were previously submitted prior to clearance of
the environmental review. Under the proposed revision, reports
would be submitted and approved prior to issuance of grading or
building permits. This revision is due to liquefaction being a
design consideration that is reviewed during the check of the
structural plans. Staff has concurred with this revision.
7-07-89
75.0264
1
-
~
-
CI-A-. OF SAN BERNARDIQO - REQU()ST FOR COUNCIL AOION
>
STAFF REPORT
Page 3 of 3
The attorney's office recommends that the resolution be
adopted as an ordinance and has approved the attached. Agreement
was reached that an enabling ordinance be adopted followed by a
resolution setting forth the specifics of the reports. The
resolution will be presented to the Mayor and Common Council at
the next regular meeting along with final adoption of this ordi-
nance.
The proposed ordinance will provide a reasonable approach
to protection of developments from the potential of liquefaction,
and set our procedures similar to those of other agencies.
We recommend that the ordinance be adopted.
URGENCY CLAUSE:
The Legislative Review Committee indicated that this ordinance
be on the Council Agenda of 7-17-89. It is necessary to have
this ordinance adopted as soon as possible, in order to bring
our procedures for processing developments into line with other
agencies.
7-07-89
75.0264
.
>.
=
",=
",:2
> !Q.
5 <~
- -lI>
CD 0:1
- cOO
...... 0
Cl. ._ c
w ';.2
(,) u-
00 ol;l
:;) ....1-
,ft $ $
w _:I
Z ",er-
o .5::;
- oc,c
ClO I- 00
... (,) ~,-
<0.::1:
w u. <Q...
a: w 0
S :;)0 /\
_ ,:z:\
II. ....I I I
"'S
"''''
$~
~$
<'8~
02=
-a
co;
o-Q.
=.c CD
~,2'lil
oX :I
....I >.00
$- c
-$0
caiG_
E~-
._CDU
)(1:1 '"
eo~
Q.2:1
<~.~
0....1
r,
'.1
I:Z:\
I. I
L
o
I co c'E
CD ~aQ;o"6
= cnClU-_.
.:..iii1icaCD~
..._...CD.c.~ .
01:l:l! 0 "'c=
- ::I=."DN"C::I ca~
-..!.c c = f:1'0.~
'5 ::I . -~ -
=c't).o~et::~ca
-.2 c~ Q.5 oas- Q
!u::l... _..CD..c
:I",e~=~~$E2 cc
CI)'Gcc;:f ,c.!c CD
fa =i s.c oc;:s ~rJ ~
cngu_cn.....,^::I.. ,-,
.- ::1....= CDc",v'o C
-g~"21:i'i.l ~ E~.! 2 '-f\
....-- CD en C'II - CD :, ,---',
-~ c c CiO CD "" -u.. - ."
:I,c2l1>col:E",'O (,) , "
CDu:-c>>o.i"x.t: "D I ..!I
.c. uis N en . ca CD ca c: 1 J
O=.!'O~"ii.a E-o E ca I ~
- 0 $ "'= ~ = C $:;:: · ft. :.
-.=-_'-0-"<_ _ I:;' 1/. ;J
OO...--acCC '" '" ,
z U::-a:;:: 0 0 '" c >. 2 ' ,
.. == .:s! ~="D ci..C!~ ... 1----' tr~J1 _I
CDU"'=U"DtD-w- CDI ~I
o !,.!,g ~;:3 ~ CD i = L.__, rr7
Z en I: en en u.Q~=u.. 5.. , ....,
,
,
"
______.:...1
,
~
- "
~A '1JOI'f
" '_I
,
,)
1
-I
=~
_0
eA. _1'4
IS"'I~IY
~z
~
;:::
~
~
0:
o
<J
~
o
$.2
:s:
~
~ 1
.
i
;;
.
~
: L:;-
,
"~1;~ "=-,
__J
;; t.......;
I. I I-I!
r-
,
,
.-
,
,
,
,
,
L.___ i
I ..
r---l ,{ j
I L_...r
,
I
I
./"
\
\
I
I
/
:
~
,
L,
r-, -,
, , /
, -...-, /
, "l'Ill;- /'
,- ;~--"\:J
~-- l~
,I ,
" ,
- -'
-'
1"-
,
,
,
-,
,
/
1/'__1
'. I
','<',-/
" ,
'-_I
---..
Va;
.
.
::l
I
,;
, ?-q
-,
,
:
-
....
1
\
:5 :' ,-
: L
:5 ('0 J
I~'
I ,
"
..W' .."....
-I"
"
,
,
,
JI
i
I
~
JI ""'d
'__1
.l__
.
c
i ;;
IE i
~
'"
$
1;
'ij
g
'"
<
$
i
00
.!-
j
i
o
(,)
0
.
1
2
3
4
5
6
7
8
9
10
11
l2
13
14
15
16
l7
l8
19
20
2l
22
23
24
25
26
27
28
o
o
o
ORDINANCE NO.
AN ORDINANCE OF THE CITY OF SAN BERNARDINO ADDING CHAPTER
15.08 DEALING WITH LIQUEFACTION AND REQUIREMENTS FOR DEVELOPMENT
IN SUSCEPTIBLE AREAS.
THE MAYOR AND COMMON COUNCIL OF THE CITY OF SAN BERNARDINO
DO ORDAIN AS FOLLOWS:
SECTION l.
Chapter l5.08 is added to the San Bernardino
Municipal Code as follows:
"Chapter l5.08
LIQUEFACTION
l5.08.0l0 Findings.
Local governing bodies are required to adopt policies for
the protection of the community against geologic and seismic
hazards pursuant to California Government Code Section 65302.
The primary geologic and seismic hazards that could potentially
affect San Bernardino include fault rupture, ground shaking,
historic high ground water, and soil matrix. These hazards could
cause liquefaction resulting in extensive property damage and
loss of life in susceptible areas of the City.
Liquefaction
reports plus mitigation measures for new development in
susceptible areas will greatly reduce the risk of damage from
liquefaction induced building failures during an earthquake
occurrence.
15.08.020 Purpose.
The purpose of this code is to reduce the potential risk of
property damage and loss of life due to liquefaction induced
building failures during an earthquake occurrence by requiring
liquefaction reports and mitigation measures for development in
areas susceptible to liquefaction within this jurisdiction.
PZ/dys
July lO, 1989
1
0
.
1
2
3
4
5
6
7
8
9
lO
II
l2
l3
14
15
16
17
l8
19
20
21
22
23
24
25
26
27
28
o
o
o
l5.0S.030 Scope-Map.
A Map is included in the General Plan indicating areas of
liquefaction susceptibility.
All new development projects, or
structural modifications over twenty-five percent (25%) of the
building area, which are located within the areas of liquefaction
susceptibility as determined by the latest adopted edition of the
General Plan Map (Map) may be required to provide liquefaction
reports and mitigation measures.
The liquefaction
susceptibility areas indicated on the map have a historic high
ground water table within thirty (30) feet of the surface.
l5.08.040 Liquefaction Defined.
Liquefaction is defined as the transformation of a
granular material from a solid state into a liquefied state as a
consequence of increased pore-water pressures. Soils and clastic
sediment with particle size in the medium sand to silt range, as
determined by the Unified Soils Classification System, are
particularly susceptible to liquefaction when they are saturated
with water and shaken by an earthquake. Liquefaction at or near
the surface can result in foundation failure and property
damage.
l5.0S.050 Reports Required.
A. A liquefaction report plus mitigation measures
prepared by a Registered Civil Engineer shall be required
by the Director of Public Works/City Engineer for new
construction or structural modification of more than
twenty-five percent (25%) of the building area for the
buildings or structures listed below which fall within the
PZ/dys
July lO, 1989
2
0
.
1
2
3
4'
5
6
7
8
9
10
11
l2
13
l4
15
16
17
l8
19
20
2l
22
23
24
25
26
27
28
II
o
o
o
high liquefaction susceptibility areas as indicated on the
Map:
l. Essential facilities, as defined in Section
2312(K) of the Uniform Building Code, including but
not limited to hospitals and other emergency medical
facilities, fire and pOlice stations, and government
disaster operation and communication centers.
2. Buildings where the primary occupancy is for
assembly use for more than fifty (50) persons in one
room.
3. Buildings over two stories in height.
4. Buildings with the following occupancies, as
listed in the Uniform Building Code:
a. Group A, (Assembly) Divisions 1, 2 and
2.l;
b. Group E, (Educational) Division 1;
c. Group H, (High Hazard) Divisions land
2; and
d. Group I, (Institutional) Divisions 1
and 2.
5. Buildings with an occupant load of more than
300, as determined by Table 33-A of the Uniform
Building Code.
6. Underground tanks of more than 5,000
gallons, for storage of toxic, hazardous or flammable
materials.
7.
Tanks with a height of more than 35 feet.
PZ/dys
July 10, 1989
3
0
.
1
2
3
4
5
6
7
8
9
10
II
l2
l3
l4
15
16
17
l8
19
20
2l
22
23
24
25
26
27
28
~
L
o
o
o
8. Towers with a height more than 35 feet.
B. A liquefaction report plus mitigation measures
prepared by a Registered Civil Engineer may be required by
the Director of Public Works/City Engineer for new
construction or structural modification of more than
twenty-five percent (25%) of the building area for the
buildings or structures listed below, which fall within the
moderately high to moderate liquefaction susceptibility
areas as indicated on the Map:
l. Essential facilities, as defined in Section
2312(K) of the Uniform Building Code, including but
not limited to hospitals and other emergency medical
facilities, fire and pOlice stations, and government
disaster operation and communication centers.
2. All structures listed in Subsection
15.08.050A, when the Director of Public Works/City
Engineer determines a report is needed based on
current data.
l5.08.060 Exemptions.
The following buildings and structures shall be exempt
from providing a liquefaction report:
l. A single-family wood frame detached
residential structure.
2. A two-dwelling unit wood frame single-story
attached residential structure.
3. Additions up to twenty-five percent (25%) of
the area of the original structure, except when the
PZ/dys
July 10, 1989
4
C
1
2
3
4
5
6
7
8
9
10
11
l2
l3
14
15
16
17
l8
19
20
21
22
23
24
25
26
27
28
.L
o
o
o
addition increases the occupancy to a level requiring
a report under Section 15.0S.050.
4. One or two story wood frame structures,
whose occupancy is not listed in Section l5.08.050.
5. A non-essential structure, where the
developer has assumed the site will liquefy and has
designed for liquefaction. Plans must be signed by a
Registered Civil Engineer and contain a statement to
the effect that the building has been designed to
withstand liquefaction.
6. Underground storage tanks of 5,000 gallon
capacity or more that are designed and installed with
flexible couplings and other features designed to
provide tank integrity and prevent leakage during
seismic events.
15.08.070 Administration and Enforcement.
The Director of Public Works/City Engineer shall
promulgate written procedures, regulations, guidelines and fees
pertaining to the implementation and enforcement of this chapter.
Such procedures, regulations, guidelines and fees shall not
become effective until they have been approved by the Mayor and
Common Council.
l5.08.080 Compliance Required Prior to Issuance of Permits.
Any person, business, organization or corporation failing
to provide the required liquefaction reports and mitigation
measures to the Director of Public Works/City Engineer in
compliance with this chapter shall be denied issuance of grading
PZ/dys
July lO, 1989
5
o
L .4
~
-
o
o
o
1 and building permits.
2 l5.08.090 Appeal.
3 Any interested person aggrieved by the determination of the
4 Director of Public Works/City Engineer may appeal the decision
5 to the Mayor and Common Council in accordance with the
6 provisions of Chapter 2.64 of this Code."
7 I HEREBY CERTIFY that the foregoing ordinance was duly
8 adopted by the Mayor and Common Council of the City of San
9 Bernardino at a meeting thereof, held on the
lO day of , 1989, by the following vote, to wit:
II AYES: Council Members
12
13
14
NAYS:
ABSENT:
l5
16
City Clerk
l7
l8
The foregoing ordinance is hereby approved this
day
of
, 1989.
19
20
W. R. Holcomb, Mayor
21 City of San Bernardino
22 Approved as to form
and legal content:
23
24
JAMES F. PENMAN,
City Attorney
25
,~
26
27
28
PZ/dys
July 10, 1989
6