HomeMy WebLinkAboutTract Map 3646 Lot 1 Geotechnical Investigation
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SOIL AND FOUNDATION (GEOTECHNICAL) INVESTIGATION REPORT
LOT 1 OF TRACT 3646
A.P.N. 922-190-012
VALLEJO AVENUE
TEMECULA. CA
CALIFORNIA
FOR
MR. AARON SMITH
RECF\VED
DEe 91999
Gill V, I t,vltCULA
ENGINEERING DEPARTMENT
PROJECT NO. 99-099.PI
DATED NOVEMBER 29. 1999
Lakeshore Engineering
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LAKESHORE
Engineering
Consulting Civil Engineering and Geologists
November 30, 1999
Project No: 99-099.PI
Client:
Mr. Aaron Smith
46701 Pa1a Road #A
Temecu1a, CA 92592
(909) 315-5051 or 507-0094
Subject:
Soil and Foundation (Geotechnical) Investigation Report
Proposed Single Family Residence
Lot 1 of Tract 3646
Vallejo Avenue, Temecula, CA.
A.P.N. 922-190-012
INTRODUCTION
This report presents the findings and conclusions of a soil and
foundation investigation for the proposed development of a single
family residence to be located at the subject site. The purpose of
this investigation was to 1) evaluate the foundation and subsurface
soil conditions at the site, and to 2) provide pertinent grading and
foundation design recommendations for the proposed development.
This investigation included the following scope of work:
1) Performed three exploratory trenches within the proposed
building pad area to determine subsurface conditions
and recover soil samples for laboratory testing (Appendix A).
2) Laboratory testing of a representative soil sample to
determine the soil properties (Appendix B). Expansion Index and
Maximum dry density were performed.
3) Engineering analyses for foundation and necessary
earthwork preparation.
4) The preparation of this report.
PROPOSED DEVELOPMENT
The proposed development will consist of a two story, custom built,
single family residence of about 4,000 square of living space,
founded on a level graded pad. A detached guest home of about 1,400
square feet is also planned to the east of the main residence.
Construction is expected to be of woodframed and stucco supported on
conventional spread footings.
The lot is relatively level, consisting of gentle rolling terrain
with slopes of less than 5 percent. In that regard, grading will be
limited to leveling of the building pads and providing positive
drainage flowlines away from structure.
\
31740-2 Railroad Canyon Road. Canyon Lake, CA 92587 . (909) 244-2913 . FAX: (909) 244-2987
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VICINITY MAP
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LAKESHORE
Engineering
LOT 1 TR: 3646
VALLEJO AVENUE
TEMECULA, CA
AARON SMITH'S PROPERTY..
:-;":'
i:i"
~No:
CONSULTING CIVIL ENGIN~ERS 99-99.PI
Dote Rgure No:
11-30-1999 1
p.
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November 30, 1999
Project No: 99-099.PI
Page Two
SITE DESCRIPTION
The subject site, approximately 2.82 acres is relatively level, with
rolling terrain of less than 5 percent grade, and slopes gently down
from street, Vallejo Avenue. It is located on north side of Vallejo
Avenue, a paved city street (no berm) and is the second lot to the
east from La Paz Street. The cul-de-sac is elevated about 15 feet
above the existing pad contours. Maximum relief on the property is
about 8 feet.
The property is at present unimproved, and supports annual grass,
recently disced. Historical use may have supported farming and/or
ranching. The surface is free from debris and contour lines are
smooth and uniform. No distinct line of drainage crosses this
property. Drainage is by surface sheetflow towards the east center of
the property line.
SUBSURFACE CONDITIONS
Three exploratory trenches were dug in the area of the proposed
buildings. Base on our exploratory trenches, the site is covered with
a loose and dry topsoil layer of about 30 inches, underlain by native
alluvium layer of Sandy SILT, firm/dense, reddish brown and moist, to
the depth of exploratory trench at 6 3/4 feet. Clay is present in
trace. Bedrock pauba formation is expected to be at relative shallow
depths of less than 20 feet.
REGIONAL GEOLOGY SETTING
For site geologic conditions, groundwater, faulting and seismicity
and secondary effects, please refer to geology report prepared by Mr.
Johnathan L. Rossi, report dated December 1, 1999 (P.N.0990045.01)
attached in the appendix as part of this report.
CONCLUSION AND RECOMMENDATIONS-GENERAL
From a soil and foundation engineering standpoint, the site will be
suitable for the proposed single family residential construction,
provided all conclusions and recommendations presented in this report
are incorporated in the project plans and specifications.
GRADING AND EARTHWORK
Based upon our review of rough grading plan prepared for the subject
property, it is our understanding that site grading will be required
to provide: 1) a level building pad for both the main house and the
guest unit; 2) suitable foundation conditions to support the proposed
building structures; 3) adequate surface gradients for control of
water runoff; and 4) excavation into engineered fills to accommodate
the installation of foundation and utility systems.
Lakeshore Engineering
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November 30, 1999
Project No: 99-099.PI
Page Three
After the areas to be rough graded have been stripped and cleared of
vegetation, the on-site soils will be considered satisfactory for
reuse in the construction of the on-site fills. The proposed site
grading plan indicates a fill pad supporting the two buildings at
finish grade from 6 inches to 3 feet above adjacent native grades.
The upper 30 inches of topsoil as encountered in our exploratory
trenches are relatively dry and loose (porosity visible) and
considered unsuitable for structural support in its present state/
condition. In this regard, the upper existing 30 topsoil within the
proposed building areas should first be removed and/or overexcavated
before fills can be placed. Depth of excavation is estimated at 30
inches, however, actual depths of over excavation should be determine
by the field geologist or engineer at the job site during grading
operations. The bottom of excavation should first be scarified
another 12 inches and densified to at least 90 percent of the maximum
laboratory dry density as determined by the A.S.T.M. D1557-78
compaction method. Boulders encountered during grading that are 6
inches in diameter or larger, should not be used in structural fills.
Overexcavation should extend at least 5 feet horizontal beyond the
building footprints.
Any surface or subsurface obstructions encountered during grading
such as rocks, utility/irrigation lines should be removed from any
areas to receive fill. No underground obstructions nor facilities
should remain in any structural areas which receive compacted fills,
building foundations, concrete slabs and/or pavements.
Depression and/or cavities (exploratory trenches) created as a result
of the grading obstruction removal, should be properly backfilled
with suitable fill materials and compacted under engineering
observation and testing. All fills should be densified in conformance
with the appropriate grading code but shall be less than 90 percent
relative compaction by mechanical means only.
EXCAVATING AND RIPPABILITY
Rework of the on-site soils should not be difficult to accomplish
with standard earthmoving equipment such as a D-5 or larger. The
walls of temporary construction excavations should stand nearly
vertical, provided the total depth does not exceed 5 feet and
surficial stability is verified. Shoring of excavation walls or
flattening may be required if greater excavation depths are
necessary. For deeper cuts, slopes should not be made steeper than
1:1 (H:V).
Lakeshore Engineering
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November 30, 1999
Project No: 99-099.PI
Page Four
All work associated with trench shoring must conform to the State of
California Safety Codes. Native organic free soils may be permitted
provided both the backfill and the native materials have a minimum
sand equivalent of 30 and the required relative compaction can be
achieved.
GRADING CONTROL
All grading and earthwork including trench backfill should be
performed under the observation and testing of the soils consultant
or their representative. Sufficient notification prior to stripping
and earthwork construction is essential in order that the work be
adequately observed and tested. In order for us to provide a written
opinion as to the adequacy of the soil compaction and trench
backfill, the entire operation, most importantly at the time of
trench backfill, should be performed under our observation and
testing.
FOUNDATION DESIGN
FOOTING
The proposed single family residential development may be supported
on conventional spread footings established in engineered (compacted)
fills. These spread footings may be designed for an allowable bearing
value of 1200 pounds per square foot. This design value may be
increase by one third, if the Structural Engineer takes into
consideration short duration structural loading conditions, such as
induced by wind and/or seismic forces.
Footings should be founded at least 18 inches below the lowest
adjacent ground surface, for one and/or two story structures. All
continuous foundations should be reinforced with at least one no. 4
rebar at top and one at bottom and consistent with the
recommendations of the Structural Engineer or Architect and the
guidelines in the U.B.C. Reinforcement should also be placed across
garage grade beam at door opening.
SETTLEMENT
Total settlement due to structural loads should not be a design
factor as they should be less than 3/4 inch. Differential settlement
should be within tolerable limits.
Lakeshore Engineering
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November 30, 1999
Project No: 99-099.PI
Page Five
LATERAL CAPACITY
For design, resistance to lateral loads can be assumed to be provided
by friction acting at the based of the foundations and by passive
earth pressure and may be combine without reduction. If passive earth
pressure is used, it is important that backfill should be placed
under engineering observation and testing.
A coefficient of friction of 0.27 may be used with the dead load
forces. An allowable lateral passive earth pressure of 200 pounds per
square foot per foot of depth may be used for the sides of footings
poured against undisturbed and/or recompacted soils.
The lateral bearing values indicated above are for the total of dead
and frequently applied live loads. If the normal code requirements
are used for seismic design, the values may be increased by 1/3 for
short durations of the loading which include the effect of wind or
seismic forces.
RETAINING WALLS No retaining walls are proposed at this time.
SLOPE STABILITY
Proposed slopes as shown on grading plan are less than 5 feet in
height to be sloped at less than 4:1 (H:V). Slopes to be constructed
as proposed are considered grossly stable.
CONCRETE SLAB - ON - GRADE
The onsite native and stockpile soils are silty (with fine sands) in
nature and considered to be Low/Medium in expansion potential, E.I =
42. The onsite soils can be used as pad fills and the proposed
concrete floor slabs may be supported directly on properly prepared
subgrade. presaturation of the upper subgrade to at least 120 percent
over optimum and 12 inches penetration is suggested, before concrete
pour. If a floor covering that could be critically affected by
moisture, such as vinyl tile, slabs should be protected by a plastic
vapor barrier of six-mil thickness. The sheet should be covered by at
least two-inches of clean sand to prevent punctures and aid in
concrete cure.
The concrete floor slabs should be reinforced with at least 6" x
6"-#10 /#10 welded wire mesh or equivalent bar reinforcing (no. 3
rebars at 24 inches on center) and installed at mid-height (using
chair support). Concrete floor slabs should be at least 4 inches
thick nominal.
Lakeshore Engineering
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November 30, 1999
Project No: 99-099.PI
Page Six
SITE DRAINAGE
Positive drainage should be provided around the perimeter of all
structures to minimize water infiltrating into the underlying soils.
Finish subgrade adjacent to exterior footings should be sloped down
and away to facilitate surface drainage. All drainage should be
directed off-site via non-erosive devices (swales and ditches).
The homeowner should be made aware of the potential problems which
may develop when drainage is altered through construction of garden/
retaining walls, patios and pools. Ponding water, leaking irrigation
systems, overwatering or other conditions which could lead to ground
saturation must be avoided.
FOOTING ~RENCH EXCAVATION INSPECTION
All footing excavations should be inspected and approved by the Soils
Consultant prior to placement of footing forms, reinforcement, or
concrete. Materials generated from footing trench excavations should
not be spread on slab-on-grade areas, unless they are compacted and
tested to at least 90 percent relative compaction.
GENERAL INFORMATION AND LIMITATIONS
This report presents recommendations pertaining to the subject site
based on the assumption that the subsurface conditions do not deviate
appreciably from those disclosed by our exploratory trenches. In view
of the general conditions of the area, the possibility of different
local soil conditions cannot be discounted.
It is the responsibility of the owner to bring any deviations or
unexpected conditions observed during construction to the attention
of the consulting engineer. In this way, any required supplemental
recommendations can be made with a minimum of delay to the project.
Prior to initiation of grading, a meeting should be arranged by the
developer and should be attended by representatives of the
governmental agencies, contractors, consultants and the developer.
Construction should be inspected at the following stages by the
Geotechnical Consultant.
Lakeshore Engineering
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November 30, 1999
Project No: 99-099.PI
Page Seven
o Upon completion of demolition and clearing.
o During all rough grading operations including removal
of unstable materials, precompaction and filling
operations.
o During trench backfilling but prior to paving or
other construction over backfill.
o When any unusual conditions are encountered.
The findings and recommendations of this report were prepared in
accordance with generally accepted professional principles and
practice in the field of geotechnical engineering. This warranty is
in lieu of all other warranties, either express or implied.
We sincerely appreciate the opportunity to be of service. If you have
any questions concerning this report or require further information
an~_services, plea~e contact this office at your convenience.
42
F
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dist: 3 copies to client
FY/fy
ENCLOSED:
APPENDIX A - EXPLORATORY LOGS
APPENDIX B - LAB. RESULTS
APPENDIX C - GEOLOGIC REPORT BY JOHN L. ROSSI
PLOT/GRADING PLAN IN POCKET
C2>
Lakeshore Engineering
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APPENDIX ~
FIELD EXPLORATION
Field exploration was performed using a backhoe (provided by Wally
Willette 674-5476). The soils were continuously logged by our field
personnel and classified by visual examination in accordance with the
Unified Soil Classification System. Our trench logs are attached for
review.
To evaluate the compaction characteristics of the fill material,
field density tests were performed. Also, representative bulk samples
were recovered and shipped to the laboratory in polythelene bags for
laboratory testing.
November 30, 1999
Project No: 99-099.PI
Lot 1 Tract 3646
Mr. AAaron Smith
0..
Lakeshore Engineering
PLOT PLAN
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LAKESHORE
Engineering
LOT 1 TR: 3646
VALLEJO AVENUE
TEMECULA, CA
AARON SMITH'S PROPERTY
:. \0
CONSULTING CIVIL. ENGINEERS
ProJ4lct No:
99-99.PI
~
11-30-1999
Rgure No:
2
TRENCH LOG
logged By: F'~ ~ G. 12e~-14- l'Z.l 11> "7
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Trench Orientalion:Sa I'LD\ PLA..1 ,
I Trench Dimensions: 2.u.'\O)( l:3.'LX1'oD
Groundwater Depth: l\J'-oi\J IE:- .
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LAKESHORE
I Engineering
I CONSULTING ENGINEERS AND GEOLOGIST
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TRENCH
LOG
Logged Sf ''lD~C. ee~ It>
Date 12.1 71"1'1 ,L~Zlfl,\ DI\i\~ \ :3Zl1~ ') "
Equipment: 1^t1\1!~ W1~TI
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Logged By:
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Equipment:
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LAKESHORE
Engineering
CONSULTING ENGINEERS AND GEOLOGIST
LOT 1 TR: 3646
VALLEJO AVENUE
TEMECULA, CA
AARON SMITH'S,
Fig, No, 3.&.
\'t;
PROJ. NO.
99-99.PI
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DEFINITION OF TERMS
PRIMARY DIVISIONS
CLEAN
GRAVELS
(LESS To'AN
5% FINE':'
COARSE
GRAINED
SOILS
MORE THAN
HALF OF
MATERIAL IS
LARGER
THAN NO,
200 SIEVE
FINE
GRAINED
SOILS
MORE n.AN
HALF OF
MA TERIAL
IS SMALLER
THAN NO.
200 SIEVE
GRAVELS
WORE TIIA.N
BALI' OF
COARSE
FRACTION IS
LARGER TIIA.N
NO, 4 SIEVE
SANDS
WORE TIIA.N
HALF OF
COARSE
FRACTION IS
SMALLER TIIA.N
NO, 4 SIEVE
GRAVEL
WlTII FINES
CLEAN
SANDS.
(LESS THAN
5% FINES)
SAND
WlTII FINES ~
SIL TS AND CLAYS
LIQUID LIMIT IS
LESS THAN 50%
SILTS AND CLAYS
LIQUID LIMIT IS .
GREATER THAN 50%
HIGHL Y ORGANIC SOILS
GRAIN SIZES
GRAVEL SAND
COARSE I FINE COARSE I MEDIUM I
~- 3/~' ... "'10 "'~o
U.S, STANDARD SIEVE SIZES OR NUMBERS
I
BOULDERS I COBBLES
RELA TIVE
PROPORTIONS RELA TIVE DENSITY CONSISTENCY
DESCRIPTIVE PERCENT SANDS, GRAVELS AND BLOWS/FOOT" CLA YS AND STRENGTH .. BLOWS/FOOT .
TERM NON-PLASTIC SILTS PLASTIC SILTS
VERY LOOSE o - ~ VERY SOFT o - 1/' o . ,
TRACE 1 . 10 SOFT II< - 1/2 1- "
LITTLE 11 - 20 LOOSE ~ - 10 FIRM 1/2 - 1 . . 8
Zl - 35 MEDIUM DENSE 10.30 STIFF 1-2 8 . 16
SOME
DENSE 30 .. 50 VERY STIFF 2 - ~ 16. 32
AND 36 - 50 VERY DENSE OVER SO HARD OVER. OYER. 32
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SECONDARY DIVISIONS
GW Will ended env., If"&Yel-nnd ~urel, liule or no fine..
GP
GM
GC
SW
SP
SM
SC
.... ..
Poorly ended (rav.... ;nnl-Iand mixture., linle or DO (mel,
SUty CRvat. cnvel-.and-.Ut mixture., non-plutie fin.. or
fin.. tri&h lo~ pluC:ieity.
Clay.y cn~.lI, rranl-Iand-c:1ay mixtures, pl:u,ic fmes.
w.u rraded land., rravelly landa. lieU. or no fines.
Poorly ended nnd., Invelly nnd., litel. Of no fines.
SUey '&Ad., .and-.ilt mixture., non-plauk (IOU or flOe.! with
low pluticity.
Clay.y landt, land.c1ay mixtura. plutic fines.
ML
CL
OL
MH
CH
OH
Inorp.nic ,ilt, and very fine .and., rock Oour, .ihy or clayey
fine .and. or clay.y .ilt. with .light pluticity,
Inorganic clay. or low to medium pluticicy. Il'avelly cIOlYI.
.andy claYl, ailty claya, lean clay..
Organic ai!h &nd orgamc aihy clay. or low plauicicy.
Inorganic ailt'l micaceou. or diacomaceous fine nndy or .ihy
aoil., elutic ai ca.
Inorcanic clay. of high plucicity, Cat clays.
Orranic clay. of medium to hirh plutic:icy, orgamc .il~.,
Pt Peat and ocher hirhly orrarii~ :~o{t~,
SILTS & CLA YS
FINE
#:00
_::'-iumber of blow. of 140 pound hammer falli2r 30~in co drive .. 2~in 0.0. (1~3/8~in 1.0.) Split~Spoon Sample (ASTM D 1586j,
Uncon(lned comprellive Itnngth in cona/ft u determined by laboratory teating or approximated by the St",nd",rd Pene~r,uion
T~st (ASTM D 1586), Poclr.ec PenecromeCer, Torvane, or vi.ual obaervation.
DRILLING NOTES,
1. II RING SAMPLE ~ Number of blowl per foot of a HO pound hammer r",lIing 30 in.
::: CI STANDARD PENETRATION TEST. Number o( blow. pu (oat at above-,
J, a:o SHELBY TUSE-. 3 in naminal.diamecer tub. hydraulically puahed.
4. PP = Pocke~ PenetromeCer (con./ft2).
JOB NO.:
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KEY TO LOGS
jDATE:
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:"
I FIGURE:
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APPENDIX B
LABORATORY TESTING
MOISTURE DENSITY RELATIONSHIP
Moisture- density information usually provides a gross indication of
the soil consistency and can delineate local variations at the time
of investigation and provide a correlation between soils found on
this site. The dry unite weight and field moisture content were
determined for selected samples, and the results are shown on the
trench log sheets.
MAXIMUM DENSITY- OPTIMUM MOISTURE TESTS
A selected soil sample was tested in the laboratory to determine
maximum dry density and optimum moisture content using the A.S.T.M.
D1557-78 compaction test method. This test procedure uses a 10 pound
hammer falling a height of 18 inches on each of five layers to a 1/30
cubic foot cylinder. The results of the tests are presented below:
Trench
No.
Depth
(Ft. )
Soil Description
Maximum Dry
Density (P.C.F)
Optimum Moisture
(% Dry Wt.)
T-1
0-3
Sandy SILT (ML)
trace clay
122.0
11. 5
EXPANSION INDEX TEST
A representative soil sample was collected in the field and tested in
the laboratory in accordance with the A.S.C.E. Expansion Index Test
Method as specified by U.B.C. The degree of expansion potential was
evaluated from measured soil volume changes obtained during soil
moisture alterations. The results of the test are presented below:
Trench Depth Soil Expansion
No. (Ft. ) Description Index
------ ----- ----------- ---------
T-1 0-3 Sandy SILT 42
trace of clay
Expansion
Potential
LOW/MEDIUM
November 30, 1999
Project No: 99-099.PI
Lot 1 Tract 3646
Mr. AAaron Smith
,1\
Lakeshore Engineering
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JONATHAN L. ROSSI
CONSULTING GEOLOGIST
"
REGIONAL
GEOLOGIC CONDITIONS
AT THE
SMITH PROPERTY
LOT 1, TRACT 3646; APN: 922-190-012
VALLEJO AVENUE & LA PAZ STREET
TEMECULAlRANCHO CALIFORNIA AREA
RIVERSIDE COUNTY
CALIFORNIA
PROJECT NO, 0990045,01
LAKESHORE PROJECT No, 99-5571
PREPARED FOR:
LAKESHORE ENGINEERING
31520 Railroad Canyon Road #8
Canyon Lakes, California
92587
PREPARED BY:
JONATHAN L. ROSSI, CONSULTING GEOLOGIST
P,O, Box 4018, Big Bear Lake
California 92315
December 01, 1999
\~
P.O, BOX 4018, BIG BEAR LAKE, CALIFORNIA 92315 ·
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IN: 0990045,01
TABLE OF CONTENTS
Page
1.0 INTRODUCTION
2.0 PROPOSED DEVELOPMENT
3.0 SITE DESCRIPTION
1,0
1,0
3,0
4.0 SUMMARY OF FINDINGS
4,1 Geologic Setting
4,2 Earth Materials -
4.2,1 Topsoil
4,2,2 Quatemary Alluvium
4,2,3 Bedrock - Pauba Formation
4,0
4,0
4,0
4,0
4.0
5,0
5.0 GROUNDWATER
5.0
6.0 FAULTING AND SEISMICITY
6,1 Faulting
6,2 Seismicity
6,3 UBC Seismic Design Criteria
6.4 Secondary Seismic Effects
6,0
6.0
8,0
9,0
9.0
7.0 CONCLUSIONS & RECOMMENDATIONS
7,1 Conclusions
7,2 Recommendations
10.0
10,0
10,0
8.0 LIMITATIONS STATEMENT
11,0
ACCOMPANYING MAPS. TABLES. ~LATES AND APPENDICES
Fiaures -
Figure 1 - Index Map (EQ Fault Map; 2000 sc,)------------------___m____________________________ 2,0
Figure 2 - Regional Fault & Seismicity Map -----.--------.-------------------------------------______ 7,0
Tables -
Table I - Regional Active Faulting m--------_____________________________________________m___ 6.0
Table 11- Maximum Credible EQ" Maximum Ground Acceleration ___________m_______________ 8,0
ADDendices -
Appendix - References
ii
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JONATHAN L, ROSSI
CONSULTING GEOLOGIST
np.t:p.mber 01,1999
IN: 0990045,01
TO: Lakeshore Engineering
31520 Railroad Canyon Rd, #B
Canyon Lakes, Ca, 92587
SUBJECT: REPORT - Geologic Conditions at the Site of Proposed Residential Structure,
Smith Property, Located on the North Side of Vallejo Ave., City of Temecula,
Riverside County, California, (NW1/4, SW1/4, SW1/4, Sec 18, T8S, R2W,
SBB&M),
ATTENTION: Fen Yong, RCE - Principal, Lakeshore Engineering
1.0 INTRODUCTION-
We are pleased to present this letter report of findings for the existing geologic conditions at
the proposed residential development located on Lot 1, Tract 3646, on the north side of Vallejo
Avenue, Temecula, Riverside County, California, The proposed site consists of an
undeveloped natural lot facing Vallejo Ave" east of La Paz Rd, Roads are paved without curb
and gutter,
Our scope of work is limited to providing a description of the geologic conditions present at the
subject site including general geology, faulting and seismicity, groundwater description, and
presentation in this letter report, Seismic conditions were evaluated based on published
earthquake and seismic information. Our scope of work does not address or consider any
aspects of a Phase I Site Assessment for Hazardous Materials or Asbestos containing building
materials, and is not a soils & foundation investigation, but provides geologic interpretation of
site conditions for the soils engineer and the geotechnical report,
This letter report presents our findings, conclusions, and recommendations concerning the
existing geologic and earthquake/seismic conditions present at the subject site, Our work is
provided to the soils engineer for further geotechnical evaluation.
2.0 PROPOSED DEVELOPMENT -
It is our understanding that a single family two-story wood frame residential structure with
garage will be constructed at the site, Some grading may be necessary for construction of the
building pad and for landscaping, At this time no significant cut or fill slopes proposed.
,"\
-1-
P,O, BOX 4018, BIG BEAR LAKE, CALIFORNIA 92315 ·
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-
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4000
.
feet
INDEX MAP
OF
SMITH PROPERTY
LOT 1, TRACT 3646
VELLEJO AVE. & LA PAZ STREET
APN: 922-190-012
CITY OF TEMECULA, RIVERSIDE COUNTY
CALIFORNIA
\tt>
BASE MAP: USGS 7.5 MIN. TEMECULA QUADRANGLE 1975
stale CA. Special StudIes ZOne Map - 1990
FIGURE 1
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December 01,1999
IN: 0990045,01
3.0 SITE DESCRIPTION -
The subject site is the second lot on Vallejo Ave, east of La Paz Rd, Ynez Rd, is located
approximately Yo mile to the north, and State Highway 71 is located approximately 300 ft, to the
south, Vallejo Ave, is a paved city road, The property is rectangular covering approximately
2,82 acres of relatively flat bottomland at approximately 1020-ft. elevation above sea level.
Sandy alluvial soils are present near the lower portions of the site, Older alluvial soils (Pauba
Sandstone) are present across the site. At this time the property is undeveloped, A few small
native trees are present in the area, Underground utilities are available to the site in Vallejo
Ave, No springs, seeps, or water wells were observed on or adjacent to the subject property,
4.0 SUMMARY of FINDINGS _
4.1 GEOLOGIC SETTING -
The subject site is situated at the southwestern margin of an elevated older alluvial plain
forming a pediment surface of rolling foothills north and east of the Temecula Valley, and north
of the Pauba Valley, The older alluvium in this area consists primarily of a massive, partially
cemented, well-indurated Pleistocene sandstone (Pabua Formation-Sandstone unit) exposed
across most of the region. The Pauba Formation contains a massive .to poorly bedded, reddish
brown, coarse to graded sandstone unit, in places containing thin (6" 'to 12") interbeds of grey
green to grey brown micaceous siltstone, Siltstone can be predominant in a portion of the
section with minor sandstone, In the south Temecula Valley and Pauba Valley the older
Pleistocene Temecula Arkose underlies the Pauba Sandstone, The Temecula Arkose consists
of a thick section of layered very fine sandstone to siltstone, Narrow, thin deposits of younger
alluvium are present within the erosional canyons developed within the pediment surface, The
older alluvial pediment surface is bordered on the north and east by intrusive granitic and older
marine metasediments of Bachelor Mtn, and Black Hills, Traces of the Agua Caliente Fault
zone are mapped (CDMG Santa Ana Sheet-1965) at the contact of the Pauba sandstone with
these hard rock units, The Temecula/Elsinore Graben is bordered by the Wildomar Fault on
the northeast, and the Willard Fault on the southwest. Both of these fault segments are
considered part of greater Whittier/Elsinore Fault Zone, The Pabua sandstone pediment
surface is located within the boundaries of the Perris structural block,
The Perris Block is a northwest-southeast trending structural block bordered on the northeast
by the San Jacinto Fault, on the southwest by the Whittier/Elsinore Fault System (Wildomar
Fault), on the northwest by the Chino Basin, and on the southeast by the Agua Calenti fault
Zone and Boreggo Valley, Similarly, the Santa Ana Mountains Block is bordered on the
northeast by the Whittier/Elsinore Fault Zone, on the southwest by the off-shore
Newportllnglewood - Rose Canyon Fault System, on the northwest by the Orange Coastal
Basin, and on the southeast by older cross faults in the San Diego - Baja California area,
\~
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December 01,1999
IN: 0990045,01
The closest active or potentially active faults capable of effecting the subject site (if an
earthquake event were to occur on one of these faults near the site) are the Wildomar Fault
approximately 1/4 mile to the northeast, and the San Jacinto Fault approximately 22,0 miles to
the northeast. Both of these faults are considered active, and are Earthquake Fault Zones,
The recently zoned Wolf Valley fault located some 1,5 miles to the south, on the southwest
side of the Temecula Graben, is considered a portion of the Elsinore Fault Zone, and possibly
an extension of the Willard Fault identified further to the northeast on the southwest side of the
Temecula Valley, No active or potentially active faults were observed on the subject property,
or were present on the site in the literature reviewed. The site is not included within the
Wildomar Fault Earthquake Fault Zone, Other fault features or linear fault like features are
reported on M,P, Kennedy's Map (CDMG Sp.Rpt. 131, Plate 1) within the Pauba Plain to the
north and east of the site, These faults are not Earthquake Fault Zones, and are not well
defined in the literature, The original and the second MWD San Diego Aqueducts (oriented N-
S) are located 1/2 mile to the east.
4,2 ON-SITE GEOLOGY - EARTH MATERIALS-
4,2,1 TODsoils - A thin layer of poorly developed topsoil is usually present over native subsoil
and bedrock, Topsoil in the area consist of loose, brown to reddish brown, porous, well graded
silty sands and clayey sands where shallow bedrock is present (pauba Fm, sandstone). In the
exploratory trenches a thick soil zone of layered, very porous, and burrowed silty sand alluvial
soil are typically 3 ft. to 4 ft. thick, The exploratory trench logs (Lakeshore Engineering _ Fen
Yong) are presented in the Appendix, Thicker sections of porous alluvial soil up to 7)1, ft. thick
have been found nearby (1/8 mile NW @ Coronado St.) within a localized topographic
depression. Similar depressions have been associated with nearby active faulting along the
Wildomar Fault zone,
4,2.2 Alluvium IOall - Unconsolidated soils were observed (F, Yong) to be loose to medium
dense, easily excavated thinly layered poorly graded fine to medium sand, sandy silts, and
gravelly sands, Pauba Sandstone bedrock underlies the alluvial soils a few feet below the
alluvium, Pauba Sandstone is present at the higher elevations in the local area, Pauba
Sandstone is mapped across the local area (CDMG SpRpt. 131), and is mapped at the site
(see below),
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-5-
December 01,1999
IN: 0990045,01
4.2.3 Bedrock (QDssl - Bedrock was not exposed on the site, but is seen on the adjacent
property to the east, and is mapped (CDMG 131) underlying the property, Bedrock consists of
the Quaternary Pauba Formation Sandstone, a regionally distributed poorly cemented (CaC03
& salts), friable well graded sandstone with limited poorly defined bedding, and containing
interbeds of grey to brown siltstone, The Pauba is a young continental deposit containing a
large number of sedimentary depositional structures: coarse channel fills, cross-bedding and
graded bedding, and alluvial fan structures, Pauba sandstone at the subject site consists of
reddish brown to brown well graded sandstone with a moderately high silt and clay content. In
addition to salt cementation clay acts to bind the sand grains of the arkosic sediment into
poorly consolidated continental sandstone, Excavation is relatively easy with standard
backhoe, and the Pauba stands up well in cut slopes up to 30 feet. However, the Pauba is
easily eroded, and can be cut with water where run-off is not controlled, Erosional gulling and
animal burrowing in the slope face is considered a problem with existing slopes in the area.
Bedrock is not exposed at the surface at the subject site, however is present some 3 to 5 feet
below the existing grade, Temecula Arkose regionally underlies the Pauba sandstone,
however the Temecula Arkose is not exposed at the local site area,
5.0 GROUNDWATER-
Groundwater is present throughout the region as an unconfined alluvial aquifer within the
Younger and Older Alluvium underlying the site, and in the underlying Pauba sandstone, The
bedrock is considered as moderately good water bearing aquifer, and can yield limited
amounts of groundwater to domestic water wells from primary and secondary porosity.
Regional groundwater within the graben basin occurs over a thick section of several hundred
feet, and is utilized by numerous domestic, municipal, and irrigation water wells, Localized
perched groundwater may be present at the site and typically occurs at the base of the
bedrock-weathered zone, Perched groundwater is the result of local winter season percolating
surface waters collecting over low permeability silt layers within the upper weathered Pauba
sandstone, No springs or seeps were reported on the subject site, Additional information
conceming the on-site hydrogeologic conditions may be obtained, if required, through the
review of available water well driller logs, and by additional on-site hydrogeologic investigation
under separate study,
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-6-
December 01,1999
IN: 0990045.01
6.0 FAUL riNG & SEISMICITY-
6.1 Faultina - No surficial or other evidence of active or potentially active faulting was
observed at the subject site during our field investigation. The subject site is not included in
any Earthquake Study Zone for fault hazard, The Wildomar Fault Zone located approximately
1/4 miles to the northeast, the Wolf Valley Fault 1,2 miles to the southwest, and the San
Jacinto Fault Zone located approximately 22,0 miles to the northeast are the closest Special
Study Zone faults to the site, The Wildomar Fault Zone is considered to be a high angle and
strike slip fault, strongly developed and clearly visible from aerial photographs, The Wolf Valley
Fault is described as a high angle fault possibly induced due to groundwater withdrawal in the
Wolf Valley (lower Temecula Valley), The San Jacinto Fault Zone extends along the foothills of
the San Timoteo Badlands, and at the base of the south San Jacinto Mountains. The fault
zone is considered to be a complex zone of high angle normal and strike slip faults with
multiple and discontinuous fault strands as wide as 2 to 3 miles (San Jacinto & Casa Loma
Faults San Jacinto Graben Valley), There are several other faults within the greater Southern
California area that could effect the site in terms of ground shaking in the event of an
earthquake. The following list includes some of these faults and their maximum probable
earthquake magnitude (Richter):
TABLE I
REGIONAL ACTIVE OR POTENTIALLY ACTIVE
CAUSATIVE FAULTS
FAULT DISTANCE FROM SITE MAXIMUM CREDIBLE
APPROXIMATE EARTHQUAKE
(RICHTER MAGNITUDE)
San Andreas Fault 39,0 mi. NNE 8,0 M
San Jacinto Fault 22,0 mi. NE 7,SM
Elsinore (Wildomar) Fault 1/4 mi. SW 7,S M
Banning Fault 36,0 mi. ENE 7,S M
Whittier SO.O mi. NNW 7,5 M
Sierra Madre/Cucamonga 53,0 mi, NW 7,5 M
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-8-
December 01,1999
IN: 0990045,01
6.2 Seismicitv - Based on information provided by CDMG Map Sheet 23 _ Greensfelder;
CDMG OF 92-1, .Peak Accelerations from Maximum Credible Earthquakes in California _
Caltrans 1992'; and Seed & Idriss . Ground Motion and Soil Liquefaction During Earthquakes'
(Earthquake Engineering Research Institute) the following conditions were determined for
ground accelerations at the site for specific earthquake events at or near the subject site,
Review of CDMG Map Sheet 54, which is presented in CDMG OF-92-1 as a peak ground
acceleration contour map includes the area of the subject site within the ,6 g acceleration
contour, one of the highest ground accelerations for southern California, Maximum credible
earthquake magnitudes listed in CDMG OF-92-1 and associated bedrock accelerations are
presented in TABLE II below,
The subject site should perform essentially as a bedrock or stiff soil site because of the very
close proximity of bedrock, and the limited volume of alluvial fill overlying the bedrock at the
site, Repeatable ground accelerations and ground surface deformation will occur to a greater
extent in the alluvium than at a bedrock site, The Pauba sandstone can be considered stiff
alluvial soil or soft bedrock,
TABLE II
MAXIMUM CREDIBLE EARTHQUAKE
PEAK GROUND ACCELERATION
REPEATABLE GROUND ACCELERATIONS
CAUSATIVE FAULTS
FAULT DISTANCE I MAGNITUDE I PEAK REPEATABLE
ACCELERATION
ACCELERATION
WILDOMAR X:l:mi. 7,5 M_ ,73 g .475 g
SAN JACINTO 22,0:l:mi. 7,5 M ,250 g ,165 g
SAN ANDREAS 39,O:l:mi. 8,OM .175 g ,113 g
BANNING 36,O:l:mi. 7,SM ,1559 ,101 g
WHITTIER SQ,O:l:mi. 7,5M ,100 g ,065 g
CUCAMONGA 53,0:l:mi. 7,5M ,080 g ,052 g
. Repeatable ground acceleration = .65 of maximum. g'.
These ground acceleration values are for bedrock accelerations, and can be applied for any
seismic condition stability evaluation of the subject site, Earthquake design criteria presented
in the current Uniform Building Code, or in the County of Riverside Building Code Seismic
Design Section, or design provided by the structural engineer and soils engineer in accordance
with these requirements, whichever takes precedence, should be applied to the proposed
development. Other active or potentially active faults in the region will probably produce less
sever effects on the site as a result of an earthquake event, and considering fault to site
distances will probably have a less sever to negligible effect on the site, (see Table II above),
p..
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-9-
December 01,1999
IN: 0990045,01
6.3 USC SEISMIC DESIGN CRITERIA - 97 USC .
97 UBC presents the following data based on known or assumed parameters as outlined in the
tables Section 16, Volume II, 97 UBC:
Seismic Zone (UBC Figure 16-2, regional seismic map USA) -------------------------- zone 4
Seismic Zone Factor 'Z' (UBC Table 16-1) ---------------------------------------------------- 0.40 (no units)
Seismic Source Type (UBC Table 16-U) ------------------------------------------------------ 'B'
Soil Profile Type (UBC Table 16-J) ------------------------------------------------------------- So
Seismic Coefficient 'C.' (UBC Table 16-Q) --------------------------------------------------- 0.40 N.
Seismic Coefficient 'Cv' (UBC Table 16-R) --------------------------------------------------- 0.56 Ny
Near Source Factor 'N.' (UBC Table 16-S) ---------------------------------------------------1.3 (no units)
Near Source Factor 'Nv' (UBC Table 16-T) --------------------------------------------------- 1,6 (no units)
Additional explanation as to the origins of these data can be acquired in Volume 2, Chapter
16, Division IV - Earthquake Design, Pages 2-9 thru 2-38, 97 UBC, The site is located in an
area of high regional seismicity based on UBC Map Figure 16-2. UBC 97 Map Book: 'Maps of
Known Active Fault Near-Source Zones in California and Adjacent Portions of Nevada' have
been used to locate and classify faulting for use in the above-tabled values,
6.4 Secondarv Seismic Hazards - The potential for secondary seismic effects such as
liquefaction due to the presence of granular sediments, shallow groundwater, and nearby
active faulting capable of generating large earthquake events should be evaluated by the soils
engineer. Based on our geologic observations at the site, and knowledge of the geology of
the area, we do not consider the subject site to be a high risk for liquefaction due to the
presence of the underlying cemented/clay bearing Pauba sandstone,
Other secondary seismic effects such as differential settlement/compaction, ground surface
rupture due to fault movement, or ground surface rupture due to lurching is not considered
likely, but cannot be ruled out due to the faulted nature of the region, and the close proximity
of active faulting which has produced ground surface rupture in the past. Seismically induced
landsliding is not common in the Pauba sandstone, and is considered unlikely to effect the
subject site.
Other potential secondary seismic hazards: tsunami, and seiches flooding due to reservoir
failure are considered nil due to the site location, and nature of the bedrock deposits.
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December 01,1999
IN: 0990045,01
7.0 CONCLUSIONS & RECOMMENDATIONS-
7.1 Conclusions-
. The subject site is suitable, in terms of the on site geologic conditions, for the proposed
residential construction, Topsoil and Pauba Fm, sandstone bedrock should not present
any significant geologic impediment to the excavation of the residential building pad
and foundation footings. Footings cannot be founded in porous, unsuitable soil
materials as per the soils engineer.
. The subject site is close to (1/4:t mile) the Wildomar Fault Zone, There are no reported
or mapped traces of the fault close to or on the subject site, Strong groundshaking
(secondary seismic hazard) is considered a possibility should a medium to large
earthquake event occur on the Wildomar Fault adjacent or close to the subject site,
7.2 Recommendations-
. The footing excavation should be inspected for competency by the soils engineer or the
engineering geologist prior to the setting of reinforcing steel bar, or any imported sand
or gravel base.
. Groundshaking - Due to close proximity of the active Wildomar Fault, the structural
engineer should consider seismic peak accelerations and groundshaking criteria in the
steel reinforcing design for the residential foundation,
. Drainaae Control - Any proposed building pad should be elevated above the
surrounding lot elevation a significant amount per the civil and soils engineer, in order
to allow positive drainage away from foundations, driveways, and patio slabs, Drainage
from all sources should be controlled.
. At this time we have not reviewed the proposed grading plan for the subject site, Any
proposed cut slopes (2 horz,: 1 vert,), vertical cut slope for retaining wall, cut pads, fill
slope keys, foundation footing excavations, or other graded exposures of soil or
bedrock should be inspected by the engineering geologist upon excavation.
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December 01,1999
IN: 0990045,01
8.0 LIMITATIONS.
This Engineering Geologic report section has been completed by Jonathan L. Rossi,
Consulting Geologist, Lakeshore Engineering, and licensed or certified subcontractors to
Lakeshore Engineering, It should be noted that J.L. Rossi, Consulting Geologist has been
retained for the purposes of providing geologic interpretation of existing and gathered data, to
provide the geology portion of the Preliminary Geotechnical Investigation, Our conclusions
and recommendations are based solely on the data made available to us from one site visit,
and information made available by Lakeshore Engineering, Our work has been performed in
accordance with the professional practices currently accepted in the Geotechnical Consulting
Industry today, No warranty is either expressed or implied,
Should you have any questions concerning this Letter Report of Existing Geologic Conditions
please do not hesitate to contact me at (909) 585-6184.
than L. Rossi, Consulting Geologist, CEG 14
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Page 1 of 2
REFERENCES
Association of Engineering Geologist, 1973 - Earthquake Recurrence Intervals on Major Faults
in Southern California, AEG Special Publication October 1973; D,L. Lamar, P.M, Merifield, RJ,
Proctor,
California Division of Mines & Geology - 1974; Map Sheet 23, Maximum Credible Rock
Accelerations; R Greensfelder.
----- 1992; Peak Acceleration from Maximum Credible Earthquakes in Ca.; DMG Open-File
Report 92-1; L, Mualchin, & A,L. Jones,
----- 1990; CDMG Map Sheet 54; unpublished for CalTrans,
----- 1954; CDMG SR 43; Geology of a Portion of the Elsinore fault Zone, California; John F,
Mann, Jr,
----- 1977; CDMG SR 131; Recency & Character offaulting Along the Elsinore Fault Zone in
Sountern California; M,P, Kennedy
----- 1988 - Summary Report: Fault Evaluation Program, 1986-1987, Mojave Desert and Other
Areas - Open File Report 88-1 LA; E,W. Hart, W.A, Bryant, J,E, Kahle, M,W, Manson, &
E.J, Bortugno,
----- 1967 - Geologic Map of California, Map No, 1,. Santa Ana Sheet; Jennings, C. W,
----- 1983 - The 1983 Coalinga, California Earthquakes, CDMG Special Publication 66,
J,H,Bennett & RW,Sherburne, Editors,
Dudley, Paul H" 1935 - Geology of a Portion of the Perris Block, Southern California;
California Division of Mines, California Joumal of Mines & Geology Vol. 31, No, 4, October
1935,
Earthquake Engineering Research Institute, 1982 - Ground Motion and Soil Liquefaction
During Earthquakes; H,Bolton Seed & LM, Idriss. Pub: EERI Berkley, California.; ISBN
0943198240
Earthquake Engineering, 1970 - Robert Wiegel, Coordinating Editor; Pub: Prentice-Hall, N.J"
ISBN 132226464,
Earthquake Engineering, Damage Assessment and Structural Design, 1983 - S.F. Borg;
Pub:Wiely Heyden, Ltd,; ISBN 0471262617.
Vb
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Page 2 of 2
REFERENCES
(continued)
Geological Society of America, 1982 - Neotectonics in Southern California, Guidebook Field
Trip No, 3, 4, 14,
---------- 1986 - Neotectonics and Faulting in Southern California, Guidebook Field Trips 10, 12,
18.
---------- 1987 - Paleoseismicity and Active Tectonics, The Structural Geology and Tectonics
Division, GSA,
Grey, Cliffton H"Jr, 1961 - Geology of the Corona South Quadrangle and the Santa Ana
Narrows Area, Riverside, Orange & San Bernardino Counties, California" and Mines and
Mineral Deposits of the Corona South Quadrangle, Riverside and Orange Counties, California;
California Division of Mines and Geology Bulletin 178.
Instution of Mining & Metallurgy, 1981 - Rock Slope Engineering, 3rd Edition; E, Hoek & JW.
Bray; Pub: Ins!. Mining & Metallurgy, London ISBN 0900488573
South Coast Geological Society, 1983 - Geology of the Northern Elsinore Trough, Annual Field
Trip - 1983,
United States Geologic Survey - 1985; PP 1306; 'Earthquake Hazards in the Los Angeles
Region'; J.I. Ziony,
Webber, Harold F" 1977 - Seismic Hazards Related to Geologic Factors, Elsinore and Chino
Fault Zones, Northwestern Riverside County, California,
MAPS UTILIZED
USGS 71/2' Temecula Quadrangle Topographic Map 1973 rev,
USGS 71/2' Pauba Quadrangle Topographic Map 1972
CDMG Special Study Zone Map (Earthquake Fault Zone Map), Temecula Quadrangle 71/2'
Revised Official Map January 1,1990,
----- 1967 - Geologic Map of California, Map No, 1, Santa Ana Sheet; Jennings, C, W.
--vt\.