ingmw.consrv.ca.gov/SHP/APSI_SiteInvestigationReports_OCR/... · 1990-07-03 · state of...
Transcript of ingmw.consrv.ca.gov/SHP/APSI_SiteInvestigationReports_OCR/... · 1990-07-03 · state of...
STATE OF CALIFORNIA-THE RESOUA:CCS AGENCY
OEPARTMENT OF CONSERVATION
DIVISION OF MINES AND GEOLOGY 8AY AREA M.EGIONAl OFFICE
380 CIVIC DRIVE. SUITe 100
Pt.eASANT Hill, CA 94.'!23· 1997 PHONE, I• JS) 646-5920
A TSS •99-5920
Mr. Steven A. Kupferrnan
GEORGE DEUl<MEJIAN. Go~mor
October 24 1 1990
Riverside County Planning Department 4080 Lemon Street, 9th Floor Riverside, CA 92501
Dear Steve:
We are placing on open file the following reports, reviewed and approved by the County of Riverside in compliance with the Alquist-Priolo Special Studies Zones Act:
Preliminary geotechnical and fault hazard investigation, 1.4-acre commercial development, 25217 Jefferson Ave., Murrieta area, Riverside county, CA; by ICG, Inc.; 7/3/90 with supplement of 9/~90 (County Geologic Report No. 749) .
•1.:1
Geologic fault investigation, Parcel 4, Parcel Map 7937, Murrieta area, Riverside County, CA; by California Geo Tek, Inc.; 10/8/89 with supplements of 3/29/90 and 5/28/90 (County Geologic Report No. 687).
EWH:hrk
cc: A-P file (2)i/
sincerely,
EARL W. HART, CEG 935 Senior Geologist &
Program Manager
October 16, 1990
ICG Incorporated 1906 Orange Tree Lane, Suite 240 Redlands, CA 92374
Attention: Tyrone M. Clinton Gerald J. Grimes Roy J. Rushing Dean R. Stanphill
=tiVc=t)ii>c couni:':' ~LAhnin<= i>cilll=ti:rncni:
SUBJECT: Alquist-Priolo Special Studies Zone Job No. 08-8313-001-00-00 Conditional Use Permit 3086 APN 909-030-004,005 and 006 County Geologic Report No. 749 Murrieta Area
Gentlemen:
We have reviewed your report entitled "Preliminary Geotechnical and Fault Hazard Investigation, 1.4+/- Acre commercial Development, 25217 Jefferson Avenue, Murrieta Area of Riverside County, California" dated July J.,. 1990, and your response to County review dated September 27, ,1990.
Your report determined that:
No active faults . are therefore the potential unlikely on this site.
located on the subject property, for ground rupture due to faulting is
2. Active faults are suspected to exist offsite, approximately 100 to 300 feet beyond the northeast and southwest property lines.
3. A magnitude 7.1 earthquake occurring on the Elsinore Fault Zone (Wildomar fault) located within 100 to 300 feet from the site could produce an average peak horizontal bedrock acceleration on the order of 0.72g at the site.
4. Liquefaction is considered unlikely on this site.
5. Settlement under seismic loading conditions for the on-site materials will not likely occur.
6. Fractures observed in the northeast portion of Trench 3 may be indications of previous ground lurching on the site, however ground lurching is not anticipated to cause significant structural damage on the site.
4080 LEMON STREET, 9TH FLOOR RIVERSIDE, CALIFORNIA 92501 (714) 787-6181
79733 COUNTRY CLUB DRIVE, SUITE E BERMUDA DUNES, CALIFORNIA 92201
(619) 342-8277
Alquist-Priolo Special Studies Zone Conditional Use Permit 3086 County Geologic Report No. 749 Page 2
7. Earthquake induced landslides, lateral spreading, flooding due to tank failure, seiching and flooding due to dam failure are considered unlikely at this site.
a. Subsidence due to groundwater withdrawal will not likely occur on this site.
Your report recommended that:
1. Setback zones for human occupancy structures shall be established on the site. These setback zones are established along the northeast and southwest property lines. The zones are delineated on Revised Plate 1 1 Geotechnical Map, dated September 1990, accompanying your September 27 1 1990 response letter.
2. Relative to seismic-induced ground motion, the design of structures on this site shall comply with the requirements of Riverside County and the standard practices of the Structural Engineers Association of California.
3. Fractures resulting from possible seismic induced ground lurching will be mitigated by the recommende.d areas restricted for human occupancy structures.
4. Where structures are proposed within exploratory trench locations, the trench removed and replaced as compacted fill.
10 feet of the backfill shall be
It is our opinion that the report was prepared in a competent manner consistent with the present ''state-of-the-art'' and satisfies the requirements of the Alquist-Priolo Special studies Zones Act, the associated Riverside County Ordinance No. 547. Final approval of this report is hereby given.
We recommend that the following conditions be satisfied prior to issuance of any County permits associated with this project:
1. The Restricted Setback Zones shown on Plate 1, Geotechnical Map accompanying your 9-27-90 response letter shall be delineated on the Exhibit A, Amended No. 1. These zones shall be labeled "Fault Hazard Area."
2. The following notes shall be placed on Exhibit A Amended No. 1:
a. "This property is affected by earthquake faulting. Structures for human occupancy shall not be allowed in the Fault Hazard Area."
Alquist-Priolo Special Studies Zone conditional Use Permit 3086 County Geologic Report No. 749 Page 3
b. "Riverside county Geologic Report No. 749 was prepared for this property by I.C.G., Inc. on July 3, 1990 and is on file at the Riverside County Planning Department. The specific items of concern are surface fault rupture, strong ground shaking and uncompacted trench backfill."
3. A copy of Exhibit A, Amended No. 1 with the delineated "Fault Hazard Area" shall be submitted to the Planning Department Engineering Geologist for review and approval prior to issuance of permits.
The recommendations made in your report concerning seismic/geologic hazards shall be adhered to in the design and construction of this project.
very truly yours,
Geologist
SAK:jb cc: Tripointe Properties - Engineer
CDMG - Earl Hart Building & Safety - Nortm Lostbom (2) Commerical/Industrial Team - John Ristow
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PRELIMINARY GEOTECHNICAL AND FAULT HAZARD INVESTIGATION
1.4± Acre Commercial Development
25217 Jefferson Avenue Murrieta Area of Riverside
County, California C, i;;'. I/ I~. Cl' ~- .. ( . I
PREPARED FOR
TRIPOINTE PROPERTIES, INC. 28691 Peach Blossom
Mission Viejo, California 92692
PREPARED BY
ICG INCORPORATED 1906 Orange Tree Lane, Suite 240
Redlands, California 92374
JOB NO: 08-8313-001-00-00 LOG NO: 0-4241
JULY 3, 1990
I I ICG
'" incorporated
I Inland Empire Offiee; ~l906 Orange Tree Lane, Suite 240 Rodlands. CA 92374
17141792-4222 fa" 714/798-1844
Corporate Office:
IS Mason Irvine, CA 92718 714/951-8686 fax: 714/951-6a13
•
San Diego County Office; 9240 Trade Place, Suite 100
I San Diego, CA 92126 619/538-1102 fax; 6191536-1306
Orange County Office:
I 15Mason Irvine, CA 92718 7141951-8686 fax: 714/951-7969
I I I I I I I I I I
July 3, 1990
Tripointe Properties, Inc. 28691 Peach Blossom Mission Viejo, California 92692
Attention: Mr. Rodney L. DuBois
Job No: 08-8313-001-00-00 Log No: 0-4241
SUBJECT: PRELIMINARY GEOTECHNICAL AND FAULT HAZARD INVESTIGATION 1.4± Acre Commercial Development 25217 Jefferson Avenue Murrieta Area of Riverside County, California
Gentlemen:
In accordance with your request, we have completed a Preliminary Geotechnical and Fault Hazard Investigation for the subject site. The purpose of this investigation was to provide specific information addressing the potential for surface fault ground-rupture and site preparation and design for construction of the proposed J & W Redwood facility.
From the results of this investigation, we have developed geological and geotechnical conclusions and recommendations pertinent to the proposed project.
This opportunity to be of service is sincerely appreciated. If you have any questions, please call.
very truly yours,
ICG Incorporated Inland Empire Division
'l'MC: mmf
Distribution: (6) Addressee
I Gaotechnical Sarvloos, Construction Inspection and Testing
1 1 TABLE OF CONTENTS
1 PAGE
1. 0 INTRODUCTION 2
I 1.1 Project Characteristics 2
1.2 Purpose/Scope/Authorization 3
I 1.3 References 4
2.0 EXECUTIVE SUMMARY 4
I 3.0 SITE INVESTIGATION 5
3. 1 Field Exploration 5
I 3.2 Laboratory Analyses 5
4.0 GEOLOGY 6
4.1 Geologic Setting 6
I 4.2 site Geology 6
4.3 Structural Geology 8
I 4.4 Aerial Photograph Interpretation 9
4.5 Drainage 10
I 4.6 Groundwater 10
4.6.l Subsidence 11
I 5.0 SEISMICITY 13
5.1 Regional Seismicity 13
5.2 Seismic History 13
I 5.3 Design Earthquake 14
5.4 Ground Response 15
I 5.4.l Earthquake Accelerations 15
5.5 Soil Settlement 16
I 5.6 Liquefaction 16
5.7 Ground Rupture 17
I 5.8 Ground Lurching 17
6.0 FAULT HAZARD INVESTIGATION 17
6.1 Trench 1 18
I 6.2 Trench 2 19
6.3 Trench 3 20
I 6.4 Conclusions 20
I I
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TABLE OF CONTENTS (Continued!
7.0 GEOTECHNICAL EVALUATION AND RECOMMENDATIONS
7.1 General
PAGE
22
22
7.2 Site Grading and Earthwork 22
7.2.l General 22
7.2.2 site Preparation 23
7.2.3 Preparation of Existing Soils and Bedrock 24
7.2.4 Fill Placement 24
7.3 Settlement Considerations 25
7.3.l Earthwork
7.3.2 Foundations
7.4 Surface and Subgrade Drainage
7.5 Design Recommendations
7.5.l General
7.5.2 Foundations
7.5.3 Lateral Load Resistance
7.5.4 Concrete Slabs/Flatwork
7.6 Soil Sulfate Content
7.7 Utility Trench Backfill
7.8 Pavement Design
7.9 Retaining Walls
7.10 Grading and Foundation Plan Review
7.11 Construction Monitoring
8.0 LIMITATIONS OF INVESTIGATION
Attached and Included:
Figure 1 - Special Studies Zone Map Figure 2 - Map of Historic Earthquake Epicenters Figure 3 - Geologic Map of the Elsinore Fault Zone Figure 4 - Aerial Photograph Interpretation Map Figure 5 - Seismicity for Major Faults
Appendix A - References Appendix B - Test Pit Logs Appendix c - Laboratory Test Results Appendix D - Standard Guidelines for Grading Project Appendix E - Plates 1, 2 and 3
25
25
25
26
26
27
28
28
29
29
29
30
31
31
32
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Tripointe Properties, Inc. July 3, 1990
1.0 INTRODUCTION
3ob No: 08-8313-001-00-00 Log No: 0-4241 Page 2
This report presents the results of our Preliminary
Geotechnical and Fault Hazard Investigation for the 1.4±
acre commercial development located immediately southwest of
Jefferson Avenue and approximately 835 ft northwest of its
intersection with Murrieta Hot Springs Road in the
unincorporated area of Murrieta, Riverside County,
California. The Assessor Parcel Numbers at the site are
909-030-(004, 005 and 006).
1.1 Prgject Characteristics
According to the 20-scale Plot Plan provided by the
client, the proposed commercial development is to
consist of a single story 1,700 ft 2 wood frame building
with a slab-on-grade floor and associated parking and
storage areas. It is anticipated that minimal grading
will be required to prepare the building, parking and
storage areas. On-site sewage disposal is proposed for
this site and a percolation investigation for leachline
sewage disposal was performed in conjunction with this
investigation. The results of the percolation
investigation are presented in our report dated July 3,
1990, Log No: 0-4255.
The site was previously utilized as a landscape nursery
facility (Hydrotech consultants, Inc., 1988). At the
time of our investigation a mobile home was located on
the site as shown on our Geotechnical Map, Plate 1,
included in Appendix E. An on-site sewage disposal
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Tripointe Properties, Inc. July 3, 1990
Job No: 08-8313-001-00-00 Log No: 0-4241 Page 3
system exists adjacent to this mobile home and leach
lines were encountered in the southwest portion of
Trench 1. The location of the septic tank was shown
the Plot Plan provided by the client (see Plate l
included in Appendix E).
The topography of the site is inclined approximately
2±% to the east. Vegetation on-site is relatively
sparse with the exception of trees (estimated 10) on
the southwest portion of the property.
1,2 Purpose/Scope/Authorization
on
our investigation was divided into 2 phases: Phase I
consisted of a Fault Hazard Investigation of the site,
while Phase II consisted of a Preliminary Geotechnical
Investigation of the proposed building area. The
purpose of Phase I of our investigation was to
determine the potential for surface fault ground
rupture on the property. The purpose of Phase II of
our investigation was to determine geotechnical
engineering parameters for the site and develop
conclusions and recommendations relative to site
grading and the design and construction of the proposed
commercial structure. The scope of this work was
outlined in our Proposal ICG-0-7951, dated May 4, 1990
and was verbally authorized on May 24, 1990 by Mr.
Rodney DeBois.
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Tripointe Properties, Inc. July 3, 1990
Job No: 08-8313-001-00-00 Log No: 0-4241 P<1ge 4
1.3 References
For the purpose of this investigation we were provided
with a copy of the 20-scale Plot Plan of the site which
was used as a base for our Geotechnical Map, Plate 1,
included in Appendix E. A "Hazardous Waste Assessment"
of the site was performed by ICG Hydrotech, Inc.,
report dated November 30, 1988. Other references are
listed in Appendix A.
2.0 EXECUTIVE SUMMARY
Our conclusions and recommendations are based on the
information obtained during our investigation of the site.
Our work was limited to the scope requested and specifically
addresses the proposed project as described herein. In
summary, our findings are as follows:
1. The proposed project is feasible for development from a
geotechnical standpoint provided the recommendations
contained in this report are implemented during
planning, design and construction.
2. The site is generally underlain by bedrock of the
Unnamed Sandstone Formation. Appropriate grading and
design recommendations are presented herein.
3 •
4.
Liquefaction at the site is considered unlikely.
The entire site lies within an Alquist-Priolo Special
Studies Zone (see, Figure 1). Our fault trenches did
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Tripointe Properties, Inc. July 3, 1990
Job No: 08-8313-00l-oo-oo Log No: 0-4241 Page 5
not encounter indications of active faulting. We
recommend a minimum 30 ft setback of human occupancy
structures from the ends of our trenches as shown on
the Geotechnical Map, Plate 1, included in Appendix E.
3.0 SITE INVESTIGATION
3.1 Field Exploration
Subsurface exploration of the site was performed
between May 30 and June 4, 1990. Three geologic fault
trenches were excavated totaling 450± linear ft to a
maximum depth of 13 ft below the existing ground
surface (see Geologic Trench Logs, Plates 2 and 3,
included in Appendix E). In addition, a total of 2
test pits were excavated by a backhoe to a maximum
depth of 8 ft. The approximate locations of the
trenches and test pits are shown on the Geotechnical
Map, Plate 1, included in Appendix E. The Logs of Test
Pits are presented on Figures B-1 and B-2 included in
Appendix B.
3.2 Laboratory Analyses
Samples, representative of the materials encountered
during our field investigation, were obtained for
laboratory testing. Results of moisture and density
determinations and soil classifications are shown on
the Test Pit Logs included in Appendix B. All other
laboratory test results and descriptions are included
in Appendix c.
I I I I I I I I I I I I I .
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\ . . ' :to,
• Q
.!ff~~~ EXPLANATION
ACTIVE; FAULT, LONG DASli WHERE APPROXIMATELY LOCATED, SHORT DASH WHERE INFERRED DOTTED WHERE CONCEALED
Q,__----0 SPECIAL STUDIES ZONE SOUNDARl!S
MODIFIED FROM: SPEQAL STUDIES ZONES MURRIETA QUADRANGLE
Rl!Yll ED OFFICIAL MAP EFFECTIVI!: JAMIARY 1, 1190
SPECIAL STUDIES ZONE MAP
JOB NO: 07-8313-001-00-0D DATI!: JULY 1990 FIGURE: 1
ICGI INCORPORAT!D-INLAND EMl>IRE DIVISDN'
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Tripointe Properties, Inc. July J, 1990
4.0 GEOLOGY
4.1 Geologic Setting
Job No: 08-8313-001-00-00 Log No: 0-4241 Page 6
The subject site is situated in the Peninsular Ranges
Geomorphic Provinces of California within the elongated
valley known as the Elsinore Trough (see Figure 2).
The Elsinore trough extends southeastward from the
Corona area to the Temecula Valley and separates the
Santa Ana Mountains, to the southwest, from the Perris
Block, to the northeast. En echelon faulting along the
Elsinore Fault Zone has created pull-apart basins; such
as the Murrieta Basin, which have caused the relatively
depressed topography along the Elsinore Trough.
4.2 Site Geology
The site is between the 2 faults which bound the
Elsinore Trough in this area. These faults are the
Willard Fault, approximately 1 mi southwest of the
site, and the Wildomar Fault, which is mapped as close
as approximately 100 ft northeast of the site (Kennedy,
1977). A right-step in the Wildomar Fault has caused a
compressional uplift creating a gentle knoll exposing
older sediments in the immediate vicinity of the site.
The site is on the northeast flank of a knoll exposing
uplifted older sediments. The sediments on-site are
mapped as being Unnamed sandstone by Kennedy (1977).
The Unnamed sandstone is unconformably overlain by the
Pauba Formation to the southwest of the site (see,
- - - -I
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- - - - - -~ ....
MAP OF HISTORIC EARTHQUAKE EPICENTERS, MAGNITUDE > 5.0 JOB NO.:
07-8313-001-00-00 DATE: JULY 1990 FIGURE:
2
- - - -.... ______ _.
..., ....
• .... ?:> --!!S~ :-
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Tripointe Properties, Inc. July 3, 1990
Job No: OS-8313-001-00-00 Log No: 0-4241 Page 7
Figure 3). The Unnamed Sandstone is not well described
(Kennedy, 1977), but is generally a fine grained
deposit typical of ponding processes (Reynolds,
personal communication, June 21, 1990). The late
Pleistocene Pauba Formation is generally a coarse
grained fanglomerate composed of siltstone, sandstone
and conglomerate and contains much oxidized iron as
described by Mann (1955). The sediments observed in
our trenches on-site were generally fine grained and
lacked evidence of iron oxide; therefore, they are
likely the Unnamed Sandstone as mapped by Kennedy,
1977). These sediments are described in our Trench
Logs, Plates 2 and 3 of Appendix E.
The age of the Unnamed Sandstone has been constrained
by fossil faunas in the Murrieta area. The youngest
the deposit can be is approximately 200,000 yr
(Reynolds and others, 1990b). The deposition of this
unit may have begun as early as 2 to 3 my ago (Reynolds
and others, 1990a).
The entire site lies within a State of California
Special studies zone (Hart, 1988; see Figure 1). The
Fault Hazard Investigation was conducted in order to
satisfy the requirements of the Alquist-Priolo Special
Studies Zone Act of 1972 for investigation within this
zone. The results of that investigation are presented
in Section 6.0.
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Tripointe Properties, Inc. July 3, 1990
4.3 Structural Geology
Job No: 08-8313-001-00-00 Log No: 0-4241 Page 8
Two major splays of the Elsinore Fault Zone are
recognized in the Murrieta area (Kennedy, 1977); the
Willard Fault and the Wildomar Fault. The Murrieta
Basin formed prior to mid-late Pleistocene between the
area of overlap between these 2 faults (Hull, 1990).
Presently the Wildomar fault accommodates most of the
dextral strike-slip movements, while the Willard fault
accommodates most of the vertical separation (Hull,
1990).
The Elsinore Fault Zone initiated in the Late Pliocene
(Hull, 1990). Approximately 6 to 9 mi of horizonal
separation has occurred since that time (Webber, 1977).
Horizonal separation rates of 5mm to 7mm per year have
occurred in the Holocene (Hull, 1990).
The Wildomar Fault has been mapped approximately 50 ft
northeast of Jefferson Avenue by Kennedy (1977) as
shown on Figure 3. Faulting was observed in sediments
estimated to be in excess of 7,000 yr old approximately
0.5 mi northwest of the site, along the mapped trace of
that fault (ICG, January 11, 1989), but it was not
continuous across that site. That report (ICG, January
11, 1989) concluded that the observed faulting was "not
the main trace of the Wildomar Fault Zone, but a less
active secondary segment".
In the vicinity of the site the State has shown (Hart,
1988) a more southwesterly branch of the Wildomar Fault
I I I I I I I I I I I I I I I I I I I
oal
Qpa
ALLUVIUM
PAUBA FORMATION
Qu• UNNAMED SANDSTONE
SYMBOLS
- - - - Gl!OLOGIC CONTACT
1~
-e-
FAULT, SOLID WHERE CONFIRMED ,DASHE:D WHERE
INFERRED DDTTED WHERE CONCEALED~-.....
INDICATES A SHEAR ZONE I.. INDICATES LATE
PLEIBTDCl!NE FAULTING
BEDDING ATTITUDE VERT.ICAL JOINT STRIKE
SCALE f'•ZOOa'
---.7$~ GROUNDWATER CONTOURS IN Ml!TEAS
GEOLOGIC MAP OF THE ELSINORE FAULT ZONE MODIFIED FROM KENNEDY 11177
JOll NO: 07-8313-001-00-00 DATE: .AJLY 1990 FIGUAI!: 3
ICG INCO_!l_PORATl!D-INLAND ~U~RE-DIV1811?N
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Tripointe Properties, Inc. July 3, 1990
Job No: 08-8313-001-00-00 Log No: 0-4241 Page 9
approximately 700 ft southwest of the fault mapped
northeast of Jefferson Avenue (see Figure 1). That
fault was found to be active approximately 0.5 mi
northwest of the site (ICG, November 23, 1988).
The above information indicates that the site is
between 2 active traces of the Wildomar Fault Zone.
Sediments, which were deposited more recently that
those exposed in the trenches on-site (Unnamed
Sandstone), were faulted by both traces of the fault
zone approximately 0.5 mi northwest of the site.
4.4 Aerial Photograph Interpretation
The aerial photographs referenced in Appendix A were
reviewed for evidence of faulting on-site. No distinct
evidence was observed on those aerial photographs for
active faults crossing or being immediately adjacent
the site. However, a relative continuous linear
vegetation contrast was noted immediately southwest of
the southwest portion of the property. Aerial
photograph interpretation by Kennedy (1977) is
presented on Figure 3. Results of our aerial
photograph interpretation are presented on Figure 4.
The results of our aerial photograph interpretation
appear to indicate that the fault mapped approximately
300 ft southwest of the site may be the thoroughgoing
trace of the Wildomar Fault Zone. Relatively young
drainages appeared to be off-set by this trace of the
fault. Less active indications of faulting exist
I I I I I I I I I I I I I I I I I I I
-' ,·,
' ·--· --- Jr
_) I\ "< (~ --···' ( ·- '
' I C:.l ···.,_)
-·--EXPLANATION
AEIUAL PHOTOORAPH LINl!AMENT
LINEAR COLOR CONTRAST
• •
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- )
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. ·• Windmill\
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"·1>=--~--:::>· - .. -~' ·~ /J ->··-..;.
SCALE ,..•2000'
AERIAL PHOTOGRAPH INTERPRETATION MAP
JOll NO: 07-8313-001-00-00 DATI!.: JULY 1980 FIGURE: 4
ICCI INCOIPORATED~INLAND _.EMJ'!RE DI VISIO_N
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Tripointe Properties, Inc. July 3, 1990
Job No: 08-8313-001-oo-oo Log No: 0-4241 Page 10
northeast of Jefferson Avenue and southwest of Adams
Avenue. our interpretation is that those faults
represent a right-step of the Wildomar fault, which
created a compressional uplift of the Unnamed Sandstone
and Pauba Formations in the vicinity of the site.
Subsequently a throughgoing fault approximately 300 ft
wouthwest of the site has taken up the majority of the
displacement.
The vegetation contrast observed southwest of the site
is approximately 800 ft long and curves to the
northeast when intersecting drainages. No clear
evidence of active faulting was observed, but if fault
related, it is likely that it would be a southwest
dipping fault. Geomorphology in this particular area
is a relatively depressed topography southwest of the
vegetation contrast indicating this may possibly be a
normal fault.
4.5 Drainage
Drainage of the site is accomplished by sheet flow in a
generally northeast direction towards Jefferson Avenue.
4.6 Groundwater
Groundwater data for years between 1953 and 1959 exists
for a well approximately 200 ft northwest (Well No.
7S/3W 21D3) of the site (Giessner and others, 1971).
The depth to groundwater in that well varied between
53.3 ft in 1953 and 71.7 ft in 1958. The depth to
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Tripointe Properties, Inc. July 3, 1990
Job No: 08-8313-001-00-00 Log No: 0-4241 Page 11
groundwater in a well approximately 300 ft southwest of
the site (Well No. 7S/3W 21D4} varied between 126.8 ft
in 1953 and 134.6 ft in 1959, but that well may be
southwest of the fault in that area.
The surface elevation of the well northwest of the site
(1127 ft} is approximately 17 ft higher than the site
(1110 ft}. Therefore, extrapolating data from the well
northwest of the site indicates that groundwater may
have been as 36 ft below the surface of the site in
1953 and 54 ft below the surface of the site in 1958.
Groundwater levels have declined significantly in this
area since 1953, with records for a well approximately
1 mi northwest of the site showing greater than a 60 ft
decline in the groundwater level (Department of water
Resources, 1977). We estimate that the depth to
groundwater under the site is most likely greater than
50 ft.
4. 6. 1 subsidence
Ground cracking or fissuring due to
differential subsidence caused by groundwater
decline is a potential hazard in alluvial
basins. This phenomenon has occurred
approximately 2 mi southeast of the site in
the Temecula Valley. Riverside County has
adopted a "Subsidence Report Zone"
(Resolution 88-61) in which structural Safety
Reports are required due to this potential
hazard. The site is not within this
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Tripointe Properties, Inc. July 3, 1990
Job No: 08-8313-001-00-00 Log No: 0-4241 Page 12
"Subsidence Report Zone" and is approximately
0.5 mi northwest of the northwest limits of
th<1t zone.
Most existing documented subsidence due to
groundwater withdrawal has taken place in
areas with relatively thick alluvial columns
and are due to rel<1tively significant
declines in the groundw<1ter table (Holzer,
1984). Evaluating the potential for
subsidence is usually dependent upon the
thickness and lithology of the sediments.
Controlling factors include compressibility,
permeability, clay mineralogy, initi<1l
porosity, previous loading history and
cementation of the sediments within the
groundwater producing zone (Pol<1nd and Davis,
1969). These controlling factors for the
sediments within the groundwater producing
zone on-site <1re not known; therefore,
predicting the potential for subsidence or
associated ground fissuring on this site is
specul<1tive.
In our opinion, significant subsidence on
site due to groundwater withdrawal will not
likely occur due to the relatively dense
nature of the sediments underlying the site.
These deposits could settle due to
groundwater withdrawal causing declines in
the watertable, but such settlement should be
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very minor and differential settlement would
likely take place along faults in the
vicinity of, but not on the site.
5.0 SEISMICITY
5.1 Regional Seismicity
The site is located in a region of generally high
seismicity as is all of Southern California. During
its design life, the site is expected to experience
ground motions from earthquakes on regional and/or
local causative faults. Figure 2 shows the geographic
relationship of these faults to the site and the
epicenters for numerous large earthquakes that have
occurred in historic time. Figure 5 lists known
regionally active faults, their maximum expected
earthquake magnitudes and their approximate distances
from site.
5.2 Seismic History
Earthquake epicenters (exceeding 6.0 on the Richter
Scale of Magnitude) within a 65 mi radius of this
project are listed below:
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Approximate Richter Distance From Site
Date Magnitude To Epicenter rmil Fault
1812 7+ 37 w Newport-
Inglewood
1890 6+ 40 N San Jacinto
1899 6+ 57 N San Andreas
1907 6+ 37 N San Andreas
1910 6+ 7 NW Elsinore
1918 6.8 20 NE San Jacinto
1923 6.3 28 N San Jacinto
1933 6+ 50 w Newport-
Inglewood
1937 6.0 37 SE San Jacinto
1948 6.5 50 NE San Andreas
1986 6.0 45 NE San Andreas
1987 6.l 50 w Whittier-
Elsinore
References: Hileman, and others, 1973
5.3
Topozada, and others, 1978 Wesnousky, 1986
Design Earthquake
A relatively large earthquake affecting the site will
likely occur on one of the previously mentioned active
faults during the design life of the project.
Earthquakes on other faults not addressed may also
affect the site, but the probability of their causing
more intense ground shaking than on faults addressed is
relatively low.
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The magnitude and distance from the site of the largest
anticipated earthquake is critical in selection of
design parameters. Moment-magnitudes expected for
earthquakes on known active faults in the vicinity of
the site are presented in Figure 5. The "design
earthquake" is the earthquake that has the highest
probability of creating the largest ground acceleration
which will effect structures on the site (Hays, 1980).
The design earthquake selected for this site is a 7.1
moment-magnitude event on the Whittier-Elsinore Fault.
The San Jacinto Fault may also cause significant ground
accelerations on the site but the expected 7.0 moment
magnitude event should produce much lower ground
accelerations than those produced by a 7.1 event on
the Whittier-Elsinore Fault.
5.4 Ground Response
5.4.1 Earthquake Accelerations
A magnitude 7.1 earthquake occurring on the
Whittier-Elsinore Fault within 1 mi of the site
could produce an average maximum peak horizontal
bedrock acceleration on the order of 0.72g at
the site (Seed and Idriss, 1982). Bedrock is
likely greater than 2500 ft below the surface of
the site (Mann, 1955). The duration of strong
ground motion is expected to be approximately 30
seconds (Bolt, 1973).
-------------------
DISTANCE FROM FAULT SITE (MILES l
Whittier-Elsinore 100-300 ft
San Jacinto 20 NE
San Andreas 34 NE
Newport-Inglewood 30 SW
Cucamonga 44 NW
1. Wesnousky (1986)
2. Seed and Idriss (1982)
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SEISMICITY FOR MAJOR FAULTS
MAXIMUM EXPECTED EARTHQUAKE 1
7.1
7.0
7. 4
6.9
6.6
ESTIMATED PEAK BEDROCK
ACCELERATION2
0.72g
0.25g
0.20g
0.18g
0.08g
Figure 5
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The surface ground motion will also be affected
by the specific materials underlying the
structures, but it is not within the scope of
this investigation to determine site specific
responses. The design of the structures should
comply with the requirements of the governing
jurisdictions and standard practices of the
Structural Engineers Association of California.
5.5 Soil settlement
Generally, the on-site materials consist of medium
dense to dense alluvial sediments. Settlement under
seismic loading conditions for these on-site materials
will not likely occur.
5.6 Liquefaction
Soil liquefaction is the loss of soil strength during a
significant seismic event. It occurs primarily in
loose, fine to medium grained, granular material with
groundwater generally within 50 ft of the surface.
Liquefaction occurs during rearrangement of the soil
particles into a denser condition, resulting in
localized areas of settlement.
Based on the geotechnical and seismological data
obtained during our investigation, seismically induced
liquefaction on this site is considered unlikely due to
the depth of groundwater likely being greater than 50
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ft below the existing ground surface and the relatively
dense condition of the sediments.
5.7 Ground Rupture
Rupturing of the ground along a trace of an active
fault is not likely, due to the absence of known active
faulting within the site bounds (see Section 6.0,
''Fault Hazard Investigation'').
5.8 Ground Lurching
Fractures observed in the northeast portion of Trench J
may be indications of previous ground lurching due to a
large earthquake in the near vicinity. Those fractures
were within the area restricted from human occupancy
structures; therefore, we do not anticipate that ground
lurching will cause significant structural damage.
6.0 FAULT HAZARD INVESTIGATION
Three trenches were excavated on-site in order to determine
if sediments exposed in those trenches had been faulted.
The approximate locations of those trenches are shown on the
Geotechnical Map, Plate 1 and geologic logs of the trenches
are presented on Plates 2 and 3 included in Appendix E. All
trenches were oriented near perpendicular to the trend of
the suspected faulting. Trench walls were vertical and
shoring was used to stabilize the trench walls. The trench
backfill was not compacted; therefore where structures are
proposed within 10 ft of the trench locations, this trench
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backfill should be removed and replaced as compacted fill.
We estimate that the actual trench locations are within 3±
ft of the locations shown on Plate 1.
The fault hazard investigation was supervised by a
California Certified Engineering Geologist. Riverside
County Geologist (Steve Kupferman) inspected the exposure in
Trench 1 on June l, 1990. A staff Geologist oversaw the
excavation of Trench 1 and prepared that trench log. The
excavation of Trenches 2 and 3 were supervised by and trench
logs prepared by a California Certified Engineering
Geologist.
6.1 Trench 1
Due to a northeasterly trending fault mapped by Kennedy
(1977) southwest of the site (Figure 3), the
southwestern portion of Trench l was oriented more
westerly in order to provide coverage for a
northeasterly trending fault. It does not appear
likely that the northeasterly trending fault exists as
far northeast as the site due to the northwesterly
trending active fault between the site and the mapped
(Kennedy, 1977) northeasterly trending fault.
Trench l was located in the Southeast portion of the
site (see Plate 1, Appendix E). This trench was
approximately 375 ft long and varied in depth from 11
to 13 ft below the existing ground surface. The
exposed stratigraphy primarily consists of thick bedded
fluvial silts, silty sands, and sandy silts. Contacts
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were gradational over a vertical distance of 1 to 2 in.
The upper 3 ft consisted of a pedogenic soil. This
soil was characterized by a moderately to well
developed argillic horizon underlain by a poorly
developed K horizon (accumulated carbonate). This
pedogenic soil is a relatively massive, silty sand with
moderate amounts of clay with significant amounts of
roots and other bio-organic features.
An offset of the bedding was suspected to exist at
approximately station 1+85. This area of the fault
trench was also suspect due to a relatively greater
abundance of carbonate (calache) stringers and an area
exhibiting iron oxide staining. Due to the relatively
gradational contacts, the suspected displacement of the
bedding could not be confirmed. This suspect fault was
closely inspected and picked by the Engineering
Geologist and no indications of fracturing or shearing
were observed.
6.2 Trench 2
Trench 2 is approximately 10 ft northwest of Trench 1.
This trench is approximately 35 ft long, and was placed
across the trend of the fault suspected to exist in
Trench 1. A thin accumulation of carbonate on top of a
slightly finer grained bed made for better resolution,
to within approximately o.5 in, of the contact on that
bed. No displacement of that contact was discernable,
but some irregularity in the bedding was observed. In
our opinion exposures in this trench were adequate to
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have exposed significant displacement of bedding and no
faults cross this trench.
6.3 Trench 3
Trench 3 was placed on the north corner of the site in
order to provide additional coverage of the
northeastern portion of the site. Bedding contacts
were relatively gradational presenting a resolution of
approximately 1 to 2 in. No significant offsets were
observed, but several near vertical fractures did exist
in the northeastern portion of the trench. These 1/8
to 1/4 in wide carbonate filled fractures died out with
depth. The northwest trend of these fractures may
indicate that they are tectonically related to the
faulting northeast of the site.
6.4 Conclusions
Based upon subsurface information obtained from
Trenches 1, 2 and J, it is our opinion that no active
faults are located on the subject property. However,
since the trenches ended at approximately the northeast
and southwest property lines and active faults are
suspected to exist from 100 to 300 ft beyond both,
respectively we recommend a minimum 30 ft setback for
human occupancy structures from the end of our
trenches.
The State does not allow human occupancy structures
within 50 ft of an active fault (Hart, 1988). This
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generally requires a 50 ft setback from the ends of the
fault trenches. The recommended 30 ft setback is less
than the generally accepted 50 ft setback, primarily
due to the restricted size of the site. In our opinion
this setback is adequate because the fault mapped
northeast of the site (Kennedy, 1977) is approximately
100 ft northeast of the site and no active faulting is
identified within approximately 300 ft of the southwest
portion of the site. The vegetation contrast observed
on aerial photographs is very near the southwest
portion of the site, but in our opinion does not
represent an active fault. Since the sediments exposed
in our trenches are at least 200,000 yr old, it does
not appear likely that a new fault plane will initiate
within the buildable portions of the site during the
life expectancy of the structure (estimated 100 yr).
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7.0 GEOTECHNICAL EVALUATION AND RECOMMENDATIONS
7.1 General
Based on the results of this Preliminary Geotechnical
Investigation, the proposed project is feasible from a
geotechnical standpoint provided the recommendations
contained in this report are implemented during
planning, design and construction. Recommendations for
site grading, foundation design and preliminary
pavement designs are presented in the following
sections of this report.
A brief summary of our findings ~s contained in the
"Executive Summary", Section 2.0.
7.2 site Grading and Earthwork
7.2.l General
All site grading and earthwork should be
accomplished in accordance with the specifications
for site grading, included in Appendix D, unless
specifically superceded herein. The
recommendations herein and the attached earthwork
guidelines should not be considered to preclude
more restrictive requirements of the regulating
agencies and/or other consultants.
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7.2.2 Site Preparation
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Prior to grading, the site should be stripped
and cleared of vegetation, topsoil and any
miscellaneous debris. Excavations resulting
from the removal of brush, debris or any buried
obstructions should be backfilled with properly
compacted fill. Cleared and stripped materials
containing vegetation and/or organic material
should not be incorporated in fills, but should
be either removed from the site or used in
landscape areas.
Abandoned and/or in-service utilities exist on
site. A septic tank is shown to exist northeast
of the existing trailer on-site (see Plate 1 1
Appendix E) and leach lines were encountered in
our Trench 1 on the southwest portion of the
site. The proper companies should be contacted
for the approximate location of other utilities.
Pipes to be abandoned should be properly capped
and/or removed off-site. Concrete pipes may be
either crushed in place or removed.
No records of abandoned wells, or underground
storage tanks exist for the site (Hydrotech,
Inc., 1988). Should any such facilities be
discovered prior to or during grading,
recommendations will be given for their safe
removal and proper backfilling of resulting
voids. Removal of underground tanks is subject
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to state law as regulated by County or city
Health and/or Fire Department agencies. If
storage tanks containing hazardous or unknown
substances are encountered, the proper
authorities must be notified prior to any
attempts at removing such objects.
7.2.3 Preparation of Existing soils and Bedrock
The on-site bedrock of the Unnamed Sandstone
Formation is considered suitable for support of
the structural frame of the proposed building
and any additional fill. Therefore, no
overexcavation, other than that considered
necessary to remove any topsoil is recommended.
Topsoil generally ranges from 1 - 2 ft in
thickness.
Prior to any additional fill placement, the
exposed bedrock should be scarified to a minimum
depth of 6 to B in, brought to near optimum
moisture content and then compacted to 90%
relative compaction (ASTM D 1557).
7.2.4 Fill Placement
All fill soils bedrock should be placed in 6 to
8 in thick loose lifts, brought to near optimum
moisture content and compacted to a minimum 90%
relative compaction (ASTM D 1557).
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Fill imported from off-site areas should have a
very low expansion potential. Imported soils
should be approved by the Geotechnical Engineer
prior to use. At least 2 working days notice
should be allowed for approval.
7.3 Settlement Considerations
7.3.l Earthwork
Subsidence of the underlying bedrock due to
movement of construction equipment is expected
to be minimal.
On-site bedrock should experience minimal volume
change from cut to fill; the exact amount of
shrinkage will depend on several factors,
including in-place soil densities and moisture
contents, as well as grading methods.
7.3.2 Foundations
Total and differential settlements under static
loads of footings supported a minimum 12 in into
competent bedrock will be minimal.
7.4 surface and Subgrade Drainage
To enhance future performance in the building pad
areas, it is recommended that all pad drainage and
runoff from roof drains be collected and directed away
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from proposed structures toward proper disposal areas.
we recollll!lend that a minimum 1 and 2% gradient away from
foundations be maintained in paved swales and soil
areas, respectively.
It is important that drainage patterns be established
at the time of final grading and maintained throughout
the life of the project. Where concentrated runoff is
anticipated, mitigation measures, such as retention
basins, etc., should be considered. It should be
understood that altered drainage patterns, landscaping,
planters and other improvements as well as irrigation
and variations in seasonal rainfall all affect
subsurface moisture conditions, which in turn could
affect structural performance.
7.5 Design Recommendations
7.5.1 General
The natural bedrock in foundation areas is
expected to be predominantly very low to low in
expansion potential; this condition should be
confirmed at the conclusion of rough grading.
One #4 reinforcing bar placed both top and
bottom is considered the minimal reinforcement
for continuous footings to resist any
differential movement of the foundation system.
A structural Engineer should evaluate
configurations and reinforcement requirements
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for structural loadings, shrinkage and
temperature stresses.
our recommendations are considered generally
consistent with the standards of Practice. The
potential for favorable foundation performance
can be further enhanced by maintaining uniform
moisture conditions during and after
construction.
7.5.2 Foundations
The structural frame of the proposed building
can be supported on shallow footings founded at
least 12 in into competent bedrock and designed
for the following net allowable bearing
pressure:
Footing Type
continuous Square
Minimum Width Depth*
Cin) Cinl
18 18
18 18
Allowable Bearing Pressure
( lb/ft2l
2500 2500
*Footing depths should be measured from the lowest adjacent grade.
These values are for dead-plus-live loads and
may be increased by 1/3 for combinations of
short-term vertical and horizontal forces.
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7.5.3 Lateral Load Resistance
Lateral loads against building foundations may
be resisted by friction between the bottom of
footings and the supporting soils. An allowable
frictional coefficient of 0.40 is recommended.
Alternately, provided the footings are cast neat
against compacted soils, an allowable lateral
bearing pressure equal to 400 lb/ft2/ft of depth
may be used, with a maximum lateral bearing
pressure of 4000 lb/ft2 • A combination of
friction and lateral bearing pressure may be
used provided the latter is reduced by 1/3.
7.5.4 concrete Slabs/Flatwork
Concrete floor slabs should be supported on a
properly compacted subgrade or competent bedrock
as recommended in Section 7.2, "Site Grading and
Earthwork" as well as a minimum 2 in sand or
gravel base (SE >30). In moisture sensitive
areas, a moisture barrier consisting of 10 mil
polyethylene sheeting overlain by 2 in of clean
sand (SE >30) should be placed between the
bottom of floor slabs and the base.
Concrete flatwork in exterior building areas
should be designed according to the expected
soils/bedrock conditions and anticipated usage.
In addition, construction joints should be
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provided at a minimum spacing of 20 ft O.C.E.W.
to reduce the effects of any possible soil
movement and concrete shrinkage.
7.6 Soil Sulfate Content
We anticipate that Type II Portland Cement may be used
in the construction of concrete foundations or slabs in
contact with the subgrade soils/bedrock. This
condition should be confirmed by performing sulfate
tests at the completion of rough grading.
7.7 Utility Trench Backfill
It is our opinion that utility trench backfill
consisting of the on-site soils/bedrock could be best
placed by mechanical compaction to a minimum 90%
relative compaction (ASTM D 1557).
7.8 Pavement Design
Our recommended preliminary pavement designs are based
on R-Value testing of the soil/bedrock which is
expected to occur at finished subgrade in the parking
areas. Based on these results, we estimate that the
in-place subgrade soils will have an actual design R
Value of about 12. The Traffic Indexes are assumed in
accordance with typical engineering practice.
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Accordingly, we recommend the following preliminary
pavement designs, subject to further evaluation and
testing at the completion of grading:
Parking/Light Drive Areas:
T.I. = 4.0/5.0 3 in Asphaltic concrete over
Heavy Drive
T.I. = 7.0
Areas:
4 in Aggregate Base
3 in Asphaltic Concrete over
10 in Aggregate Base
The top 12 in of subgrade in areas to be paved should
be scarified, moistened to near optimum conditions and
compacted to at least 90% relative compaction (ASTM D
1557). Aggregate Base should meet the requirements of
Section 200 of the Standard Specifications for Public
Works Construction (Green Book) for Processed
Miscellaneous Base (or equivalent) and be compacted to
a minimum 95% relative compaction (ASTM D 1557).
Asphaltic Concrete should meet Minimum Class C
requirements (Section 400, Green Book) and be compacted
to 95% relative compaction (CA 304).
7.9 Retaining Walls
Retaining walls should be designed in accordance with
the following criteria:
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EARTH PRESSURE (lb/ft2/ft of depth)
Unrestrained Backfill Level Soil Type Backfill
on-site alluvium 40
Walls 2:1 Sloping Back.fill
50
Restrained Walls Level 2:1 Sloping Backfill Backfill
50 60
Walls subject to surcharge loads should be designed for
an additional uniform lateral pressure. To relieve
possible hydrostatic pressures on walls, backdrains
that daylight to proper drainage devices should be
properly placed to drain the wall backfill. Backfill
soils/bedrock should be properly compacted as outlined
in Section 7.2.3, "Fill Placement", but should be
compacted to no more than 95% relative compaction (ASTM
D 1557). All on-site soils/bedrock used for wall
backfill should be approved by the Geotechnical
Engineer. Wall footings should be designed as
recommended in Section 7.6.2 "Foundations".
7.10 Grading and Foundation Plan Review
As foundation and grading plans are completed, they
should be forwarded to us for review to assure
conformance with the intentions of the recommendations
contained in this report.
7.11 Construction Monitoring
Continuous observation and testing under the direction
of our Geotechnical Engineer and/or Engineering
Geologist is essential to verify compliance with our
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recommendations and to confirm that the geotechnical
conditions found are consistent with this
investigation.
8.0 LIMITATIONS OF INYESTIGATION
Our investigation was performed using the degree of care and
skill ordinarily exercised, under similar circumstances, by
reputable Soils Engineers and Geologists practicing in this
or similar localities. No other warranty, expressed or
implied, is made as to the conclusions and professional
advice included in this report.
The samples taken and used for testing and the observations
made are believed representative of the entire project;
however, soil and geologic conditions can vary significantly
between test borings, test trenches and surface outcrops.
As in most projects, conditions revealed by excavation may
be at variance with preliminary findings. If this occurs,
the changed conditions must be evaluated by the Project
Geotechnical Engineer and Geologist and designs adjusted as
required or alternate designs recommended.
This report is issued with the understanding that it is the
responsibility of the owner, or his representative, to
ensure that the information and recommendations contained
herein are brought to the attention of the architect and
engineer for the project and incorporated into the plans,
and the necessary steps are taken to see that the contractor
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and subcontractors carry out such recommendations in the
field.
This firm does not practice or consult in the field of
safety engineering. We do not direct the contractor's
operations, and we cannot be responsible for other than our
own personnel on the site; therefore, the safety of others
is the responsibility of the contractor. The contractor
should notify the owner if he considers any of the
recommended actions presented herein to be unsafe.
The findings of this report are valid as of the present
date. However, changes in the conditions of a property can
occur with the passage of time, whether they be due to
natural processes or the works of man on this or adjacent
properties. In addition, changes in applicable or
appropriate standards may occur, whether they result from
legislation or the broadening of knowledge.
Accordingly, the findings of this report may be invalidated
wholly or partially by changes outside our control.
Therefore, this report is subject to review and revision as
changed conditions are identified.
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This opportunity to be of service is sincerely appreciated.
you have any questions, please call.
If
Very truly yours,
ICG Incorporated Inland Empire Division
Cb""~~ (b~ Gerald J. Grimes, CEG 1144 Associate Geologist Registration Expires 6-30-92
Reviewed By:
:::tz~<~~.i~E 223 &i~f E~;~!~ / -Registration Expires 12-31-90
GJG:DRS:TMC:RJR:mmf
4c;1. Roy J. Rushing, Chief Geologist Registration Expires 6-30-92
I I I I I I I I APPENDIX A
REFERENCES
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PUBLISHED REPERENCES
Bolt, B.A., 1973, Duration of Strong Ground Motion: Proc. Fifth World Conferences on Earthquake Engineering, Paper No. 292, Rome;
Department of Water Resources, 1977, Hydrologic Data: 1975, Volume V: Southern California: Bulletin No. 130-75;
Giessner, F.W., Winters, B.A. and McLean, J.S., 1971, Water Wells and Springs in the Western Part of the Upper Santa Margarita River Watershed, Riverside and San Diego Counties California: Department of Water Resources Bulletin No. 91-20, p. 377;
Hart, E.W., 1988, Fault-Rupture Hazard Zones in California, CDMG Spec. Publication 42, 24 pages;
Hays, W.W. 1980, Procedures for Estimating Earthquake Ground -Motions: U.S. Geological Survey Professional Paper 1114;
Hileman, J.A., Allen, C.R., and Nordquist, J.M., 1973, seismicity of the southern California Region, 1 January 1932 to 31 December 1972: Pasadena, California, California Institute of Technology Seismological Laboratory, 487p;
Holzer, T.L., 1984, Ground Failure induced by Ground-water Withdrawal from Unconsolidated Sediment: in Holzer, T.L. ed. Man-Indu.ced Land Subsidence, Geological Society of America Reviews in Engineering Geology Vol. 6, p.67-105;
Hull, A.G., 1990, Quaternary Faulting and Basin Evolution in the Northern Elisnore Fault Zone, California: Geological society of America, Abstracts with Programs, 86th Annual Meeting Cordilleran section, Vol. 22, No. 3, p.30;
Kennedy, M.P., 1977, Recency and Character of Faulting Along the Elsinore Fault Zone in Southern Riverside County, California: California Division of Mines and Geology Special Report, 131, p. 12;
Mann, J.F., Jr., Geology of a Portion of the Elsinore Fault Zone, California: California Division of Mines and Geology Special Report 43, p. 22;
Poland, M.R. and Davis, G.H., 1969 1 Land Subsidence Due to Withdrawal of Fluids: in Varnes, D.J. and Kiersch, G. eds. Geological Society of America Reviews in Engineering Geology Vol.2;
Reynolds, R.E. and Reynolds R.L., 1990a, A New, Late Blancan Faunal Assemblage from Murrieta, Riverside county, California: in Reynolds, J., compiler, Abstracts of Proceedings, 1990 Mojave Desert Quaternary Research Symposium, San Bernardino County Museum, Quarterly Vol. XXXVII, No, 2, p.34;
I I I I I I I I I I I I I I I I I I I
PUBLISHED REFERENCES (Continued)
Reynolds, R.E., Fay, L.P. and Reynolds R.L., 1990b, California Oaks Road: An Early-Late Irvingtonian Land Mammal Age Fauna from Murrieta, Riverside county, California: in Reynolds, J,, compiler, Abstracts of Proceedings, 1990 Mojave Desert Quaternary Research Symposium, San Bernardino County Museum, Quarterly Vol, XXXVII, No. 2, p.351
Seed, H.B., and Idriss, I.M., 1982, Ground Motion and Soil Liquefaction During Earthquakes, Earthquake Engineering Research Institute Nomograph1
Toppozada, T.R., Parke, D.L., and Higgins, C.T., 1978, Seismicity of California 1900-1931: California Division of Mines and Geology Special Report 135, 39p1
Weber, H.F., 1977, seismic Hazards Related to Geologic Factors, Elsinore and Chino Fault Zones, Northwestern Riverside county, California.
Wesnousky, S.G., 1986, Earthquakes, Quaternary Faults, and seismic Hazards in California, Journal of Geophysical Research, Vol. 91, No. 812, pp 12587-12631;
I I I I I I I I I I I I I I I I I I I
UNPUBLISHED REPORTS
Highland Geotechnical Consultants, Inc., November 23, 1988, "Preliminary Geotechnical Investigation, 36± Acre Site, SWC Kalmia Street and Jefferson Avenue, Murrieta, California", Job No: 08-6556-025-00-00 1 Log No: 8-2779;
Highland Soils Engineering, Inc., January 11, 1989 1 "Fault Hazard and Preliminary Geotechnical Investigation, 6± Acres, East of the Intersection of Juniper street and Jefferson Avenue, Murrieta, California", Job No. 087-4610-010-00-00 1 Log No. 9-2970;
Hydrotech Consultants, Inc., November 30 1 1988, "Hazardous Waste Assessment, 1.4± Acres, Located southwest and Adjacent to Jefferson Avenue between Hawthorne Street and Ivy Street, Murrieta, California, Job Na: 27-4610-007-00-00, Log No: 8-2882;
ICG Incorporated, July 3, 1990, "Preliminary Percolation Investigation, 1.4± Acre Commercial Development, 25217 Jefferson Avenue, Murrieta Area of Riverside County, California, Job No: 08-8313-001-00-02, Log No: 0-4255.
AERIAL PHOTOGRAPHS
Riverside County Flood Control District, 1-28-1962, Photograph Nos. 1-57, 1-58 and 1-59, Approximate Scale: 1" = 2000 1
;
Riverside County Flood Control District, 6-20-1974, Photograph Nos. 875, 876 and 877, Approximate Scale: 1 11 = 2000 1
;
Riverside County Flood Control District, 5-4-80, Photograph Nos. 902, 903 and 904 1 Approximate Scale: 1 11 = 1600';
U.S. Department of Agriculture, 1-28-1960, Photograph Nos. 26, 27 and 28, Approximate scale: 1 11 = 1000', on-file at our office.
I I I I I I I I APPENDIX ll
I TEST PIT LOGS
I I I I I I I I I I
-------------------PROJECT NAME: J a W REDWOOD TRENCH NO.: T-1 ENGINEERING PROPERTE8
z ... Ii: 07-8313-001-00-00 5-31-90 0 w a -JOB NO.: DATE: ~-
... Ill 0 IL ..... - IL o"! 2 Ir..< Ill -EQUIPMENT: 24" BUCKET BACKHOE < :)IL a: ,. ELEVATION: -o = IL ' w 1-::1 t: -m !!c ...
G. CASH ::i " • • LOGGED BY: LOCATION: ... a• 0 z < = z Ill ... .. = 2 a DESCRIPTION 0
CD TOPSOIL SILTY SANOY CLAY - OARK SLACK, MOIST TO SATURATED, VERY @ 1' @ 1' 11.2 120.5 OENSE, FRACTURED, EXPANSION CRACKS, GRAVEL ON TOP, ROOTS, DENSE, POROUS
@ BEDROCK WEATHERED UNNAMED SANOSTONE: LIGHT YELLOWISH BROWN, FRACTURED, @ 3' @ 3' 24.7 96.0 VERY DENSE, CONSOLIDATED, CALI CHE, IRON STAINED FRACTURE,
FEW GRAVELS, MOIST, MASSIVE, FINE TO MEDIUM GRAIN SAND
® UNNAMEO SANDSTONE: LIGHT GRAYISH BROWN, MOIST, CONSOLIDATEO, FEW COARSE ® 5' ® 5· 9.1 110.4 GRA t.I GRAV ELS, MASSI VE @ 8' @ 8' 12.4 113.1
SCALE: 1"= TOPOGRAPHY: TRENCH ORIENTATION:
- . ,.. . - c
- -.
© - le- -- ll' • ' . . . . ' ' ' ' ' ' ' I ' ' ...-. ' . ' ' ' . ' ' ' ' ' ' ' ' '
' ' ' . . . ' ' . . ' ' - ·~ - ' . . .... 1.-1- I - -· ·-- r~· ' ' . . ' ' ' ,_ ,.. - .
@ x -- --- - - -... - I IJ - c @ 1 .,) . .
J
"' x / ·~ L/ v ,_ . -
J ~ING a BULK ,_ .'filNG &SULK
. ,..
- -- .,..
TRENCH LOG ICG INCORPORATED-INLAND EMPIRE DIVIS ION
------------ - - - - -PROJECT NAME: J 6 W REDWOOD TRENCH NO.: T-2 ENG .. EERING PROPERTE8
z - Ii: JOB NO~ 07-8313-001-00-00 0 "' Cl DATE: 5-31-90
~· ... Ill - 2 IL. •111 -
o~ :I 1: ... Ill -EQUIPMENT: 24" BUCKcT BACKHOE ELEVATION: -u c :IL I: ,. .... co 1-:::1 :::. -co coc ... I: G. CASH := II: gCO • • LOGGED BY: LOCATION: ... 0 z c :::. z Ill
DESCRIPTION ... • :::. :I D 0
© TOPSOIL - SILTY SANDY CLAY, DARK BLACK, MOIST TO SATURATel>, ORGAN I CS, POROUS, MASSI VE, DEN SE, EXPANSION CRACKS
@ BEDROCK WEATHERED UNNAMED SANDSTONE: LIGHT GRAYISH BROWN, FRACTURED, @ 2' 14.2 93.4 VERY DENSE, ABUNDANT CALI CHE, FEW .ROoTs, MASSIVE, @ 4' 8.8 111.9 FINE GRAIN SAND, MOIST TO DRY
@ UNNAMED SANDSTONE: LIGHT GRAY, MOIST, MASSIVE, NO VISIBLE BEDDING, DENSE, @ 8' 17.5 104.0 CONSOLDATED
'
SCALE: 1"= TOPOGRAPHY: TRENCH ORH!NTATION:
r •r - ·- .
© _I -- . --'(_
-- ........ -,_ -@ -- -
r - ·r -. • ' • ' . ' ' . . . . X,~ 1 I ' ' ' I . ' . ~ I ' • ' ' ' I . . .
' ' ' ' ' ' ' ' I I I I ' ' . .. \ . I I ' 0 . . ' 1 ' • • I O t ' . . . '
RING I x- - ~ ]: r
- .. \ r X I . - r SAMPLE
RING 'RING - . ... SAMPLE SAMPLE - .
.
- - .
- - -- .
- -- - -- - - -
.
-TRENCH LOG ICG INCORf'ORAT ED-INLAND EMPI Re DIVISION
I I I I I I I I APPENDIX C
I LABORATORY TE.ST RESULTS
I I I I I I I I I I
I I I I I I I I I I I I I I I I I I I
LABORATORY TESTING
A.
B.
c.
D.
E.
Classification
Soils were classified visually according to the Unified Soil
Classification system. Classification was supplemented by
index tests, such as Particle Size Analyses.
Particle Size Analyses
Particle size analyses, consisting of mechanical analyses
using sieves and hydrometer analyses, were performed on
representative samples of on-site soils in accordance with
ASTM D 422. Test results are shown on Figures C-1 through
C-3.
Maximum Density/Optimum Moisture Determination
A maximum dry density/optimum moisture determination was
made for a typical sample of on-site soils. The laboratory
standard used was ASTM D 1557 (Five-Layer Method). The test
result is summarized on Figure C-4, Table I.
Expansion
Expansion tests were performed on representative samples of
on-site soils. The sample was remolded and tested under a
surcharge of 144 lb/ft2 in accordance with the Uniform Code
Standard No. 29-2. This test result is presented on Figure
C-4, Table II.
R-Yalue
An R-value test was performed on a representative sample of
the near surface soils in accordance with CA 301. The test
result is shown in Figure C-4, Table III.
-------------------~~ I II
lcil z ~o w •• I
~ I 0 0
~ .!!,__
SAND GRAVEL SILT CLAY
COARSE MEDIUM Fl NE
SIEVE SIZES-U.S. STANDARD 10 20 40 100 200
............. ~ 1a,1-U-~--J..--l-l-if-+tl--l-l+--t~-l'--~~-Rl1Ld-+-+-#-~t-~t---t~-rt-ttt-l-l---!--+-~-+-~~-+-l-f-+-+-+-+--+~-+~~-----190
I°'~
701-U-~--l-H--l--l-ll--++1---+---ll------IH -~+-f-f1----+-"'---'"'!.------t~--+rt1+--11-t-•---1-~--1-~~-1-1-1--~~---+---->~-+-~+-~~~70 '\.. ·~ ~ ~ 101-11---+-H--1-J--ll--+++-+---11----+-+tt 1---+-+---ll--+----1--+-,,.,..~-H1---+-+--1-- ~__.----~<-+-+--<--<---+-------<e---r-----1&0 ,.
.. " :a :a 0 0 .. .. .. ,, z ~ 50 511 ... .,, : . M m Cl1 40 • i 40 z Q Q
ao1Wl----l-l-++-lf--ll--+++-+-----l----~ll--1-l--l-~-+----t---t--~+fir-+---t--t--t---t----t-t-t-ir-t---t----1i----t-----i--------iJo
zo,Ul-~--J..--l--J-.lf-+tl-+l+---J..~-il~~--1+11--1-+-+-#-~t-~t---t~-rt-tlt--l-1---ll---+-~-r----1+-1rt-t--t---t------1l----lr-------i20
10Wl----i-l-++-lf--ll--i-+t-+----ll------lf-+IK-l--+---+--~l---l---+---+---+-t--1Ht-+---~- ------!--~~ - ·- ~ - ~ ~·· ---1------.10
'1-1--1--111--+--+-+--+ r- -- r--- - ----11- H- -1-1--1---+----I
10.0 t.O 0.1 .01 PA RT IC LE SIZE-Ml ILLIM ETERS
80RlHCI HO. DEPTH IF E ET SYlllOL LIQUID LIM 11 PLASTICITY IND EX CLASSIFICATION
T-1 0-2· e
-------------------SAND
GRAVEL SJLT CLAY COARSE MEDIUM FINE
SIEVE SIZES-U.S. STANDARD
.a~rr'4~·-·~1l1f2_··1'~1r'r····=itt!~:;:i:::at-~~l""f2io-rr-r-•tro~"f"~l""~1to_o~fTl2~01o"T-"r-"f"-i~~r-~~"l"Tl-rY-Y--r~r-~r-~~"1 100 1001 10
-l-+-+-ll----f~--J1---t-~-+t-t-tt-+-+--1--l---t----·l-+-l-1--i--f-l---t---+-----i90
so,1-11-~-+--l-+-!-+-ll--H+--+---llf----t-tff-ll-+_,..,
' -- --11----1-H-+-+-l-+--l---!----I '· ~ ,. 10~----t~J-+.+-1-#--+++-+-~-i!--~--jrf ~-1--1---1--11----t~~f--_,.:'---++~~1-+-+-+-+-~-+~--+++-ir-t--+--J--+--t-~----150 m
m ' ~ ~ ' 0 0 ' .. • ' z z ··~---l--l+-l--IHl--++4-+----1--~~1-t-ll--Jl-tl-t-ll-~+---t--t-~rt+fit-+-t-t---r---t-~--tt- 50 ~ ~ 50<" " .... .... > > m : 40 m i 40 z Q Q
sol-ll-~-l~l-l-.J.-1-ll--+++-+-~-ff-~~--lf-Hll-l--t---t--tt-+-~-t-~t----;r-++ttl-t-t----t--t---+-~--ri--r-i-i--i---t--r---r----.Jo
10,!4!-~--l~-l++-IHl--+-H~-f-~--jf-~~--jf-t-ll-ll-+-t--l~~-+-~-t--t---f-t-+tlf-tl-t- --->---<l---~-•++.-,>-+-+-11--t-~-+----<10
OW...~....L..-+LL.J..JJ--1..1-L~.L-~IL-~~t-L.L..JL-J..--'--..U...--l~-L~-'---jf-'-Ul.-L-.1--"'---'-~--'--~~-t_._..~~~~~~~~--:;::O 0.1 .01 • 001 10.0 1. 0
PARTICLE S IZ E-111 IL LIME TE RS
BORING HO. DEPTH IF EETI SYMBOL LIQUID LIMI" PLASTICITY INDEX CLASS IFICATlON
T-1 1' •
0 Cl
z D 0 ::a .. 0
"' ~ Ill 0 I
i .. > z CJ
'" c ... ii "' 0
< iii 0 z
-------------------~~
SAND I .. SILT Ct AV
5~ GRAVEL
COARSE I I FINE MEDIUM
•• I SIEVE SIZES-U.S. STANDARD 0 0 314•• 112·· 114"" 4 10 20 40 100 100
lOO
~ 100 ,...._ ....._ I ............... 0
90 0 90 ...... f--
10 r-i
....... 80
-"\...
70 70 -
' : .... :a ' 60
,, 10 m -I m \ .. - ::a n n C)
' m r- "' z m z 50 ... ... 50 ,, en ,, .. - > .. N ..
40 .. rn .. .- z i
~ 1:1 GI
i 30 r- 30
-< en -en 20 20
-
10 f----- --- 111
- ----- --,-
.__ 0 0 .001 ... 10.tl 1.0 0.1 .01 ii
PARTICLE SIZE-MIL LIM ET E RS c ::a !! BORING HO. DEPTH !FEET SYMBOL LIQUID LIMll PLASTICITY INDEX CLASS IFIC ATIOH
n T-1 3' • I w
I I I I I I I I I I I I I I I I I I I
TABLE I
MAXIMUM DENSITY/OPTIMUM MOISTURE RELATIONSHIP (ASTM D 1.5.57)
Test Location
T-1@ 1-3'
Test Location
T-1 @ 3' T-1 @ 3 1
Test Location
T-1@ 0-2'
Maximum Dry Density
Clb/ft2
122.0
TABLE II
RESULTS OF EXPANSION TEST (UBC standard 29-2)
Expansion Index
13 40
TABLE III
RESULTS OF R-VALUE TESTS (CA 301)
Job No: 08-8313-001-oo-oo
Optimum Moisture Content
(%)
11. 3
Expansion Potential
Very Low Low
R-Value
12
Figure C-4
I I I I I I I I I I I I I I I I I I I
APPENDIX D
STANDARD GUIDELINES FOR GRADING PROJECT
I I I I I I I I I I I I I I I I I I I
STANDARD GUIDELINES FOR GRADING PROJECT
1.0 GENERAL
1.1 The guidelines contained herein and the standard details attached hereto represent this firm's standard recommendations for grading and other associated operations on construction projects. These guidelines should be considered a part of the project specifications.
1.2 All plates attached hereto shall be considered as part of these guidelines.
1.3 The Contractor should not vary from these guidelines without prior recommendation by the Geotechnical Consultant and the approval of the Client or his authorized representative. Recommendations by the Geotechnical Consultant and/or Client should not be the controlling agency prior to the execution of any changes.
1.4 These Standard Grading Guidelines and Standard Details may be modified and/or superseded by recommendations contained in the text of the preliminary geotechnical report and/or subsequent reports.
1.5 If disputes arise out of the interpretation of these grading guidelines or standard details, the Geotechnical Consultant shall provide the governing interpretation.
2.0 DEFINITION OF TERMS
2.1 ALLUVIUM - unconsolidated detrital deposits resulting from flow of water, including sediments deposited in river beds, canyons, flood plains, lakes, fans at the foot of slopes and estuaries.
2.2 AS-GRADED {AS-BUILT) - the surface and subsurface conditions at completion of grading.
2.3 BACKCUT - a temporary construction slope at the rear of earth retaining structures such as buttresses, shear keys, stabilization fills or retaining walls.
I I I I I I I I I I I I I I I I I I I
Page 2
2.4 BACKDRAIN - generally a pipe and gravel or similar drainage system placed behind earth retaining structures such as buttresses, stabilization fills and retaining walls.
2.5 BEDROCK - a more or less solid, relatively undisturbed rock in place either at the surface or beneath superficial deposits of soil.
2.6 BENCH - a relatively level step and near vertical rise excavated into sloping ground on which fill is to be placed.
2.7 BORROW (IMPORT) - any fill material hauled to the project site from off-site areas.
2.8 BUTTRESS FILL - a fill mass, the configuration of which is designed by engineering calculations to stabilize a slope exhibiting adverse geologic features. A buttress is generally specified by minimum key width and depth and by maximum backcut angle. A buttress normally contains a backdrainage system.
2.9 CIVIL ENGINEER - the Registered Civil Engineer or consulting firm responsible for preparation of the grading plans, surveying and verifying as-graded topographic conditions.
2.10 CLIENT - the Developer or his authorized representative who is chiefly in charge of the project. He shall have the responsibility of reviewing the findings and recommendations made by the Geotechnical Consultant and shall authorize the Contractor and/or other consultants to perform work and/or provide services.
2.11 COLLUVIUM - generally loose deposits usually found near the base of slopes and brought there chiefly by gravity through slow continuous downhill creep (also see Slope Wash) •
2.12 COMPACTION - is the densification of a fill by mechanical means.
2.13 CONTRACTOR - a person or company under contract or otherwise retained by the Client to perform demolition, grading and other site improvements.
2.14 DEBRIS - all products of clearing, grubbing, demolition, contaminated soil material unsuitable for
I I I I I I I I I I I I I I I I I I I
Page 3
use as compacted fill and/or any other material so designated by the Geotechnical Consultant.
2.15 ENGINEERING GEOLOGIST - a Geologist holding a valid certificate of registration in the specialty of Engineering Geology.
2.16 ENGINEERED FILL - a fill of which the Geotechnical Consultant or his representative, during grading, has tested sufficiently to enable him to conclude that the fill has been placed in substantial compliance with recommendations of the Geotechnical Consultant and governing agency requirements.
2.17 EROSION - the wearing away of the ground surface as a result of movement of wind, water and/or ice.
2.18 EXCAVATION - the mechanical removal of earth materials.
2.19 EXISTING GRADE - the ground surface configuration prior to grading.
2.20 FILL - any deposits of soil, rock, soil-rock blends or other similar materials placed by man.
2.21 FINISH GRADE - the ground surface configuration at which time the surface elevations conform to the approved plan.
2.22 GEOFABRIC - any engineering textile utilized in geotechnical applications including subgrade stabilization and filtering.
2.23 GEOLOGIST - a representative of the Geotechnical Consultant educated and trained in the field of geology,
2.24 GEOTECHNICAL CONSULTANT - the Geotechnical Engineering and Engineering Geology consulting firm retained to provide technical services for the project. For the purpose of these guidelines, observations by the Geotechnical Consultant include observations by the Soils Engineer, Geotechnical Engineer, Engineering Geologist and those persons employed by and responsible to the Geotechnical Consultant.
2.25 GEOTECHNICAL ENGINEER - a licensed Civil Engineer who applies scientific methods, engineering principles and professional experience to the acquisition, interpretation and use of knowledge of materials of the
I I I I I I I I I I I I I I I I I I I
Page 4
earth's crust for the evaluation of engineering problems. Geotechnical Engineering encompasses many of the engineering aspects of soil mechanics, rock mechanics, geology, geophysics, hydrology and related sciences.
2,26 GRADING - any operation consisting of excavation, filling or combinations thereof and associated operations.
2.27 LANDSLIDE DEBRIS - material, generally porous and of low density, produced from instability of natural or man-made slopes.
2.28 MAXIMUM DENSITY - standard laboratory test for maximum dry unit weight. Unless otherwise specified, the maximum dry unit weight shall be determined in accordance with ASTM Method of Test D 1557.
2.29 OPTIMUM MOISTURE - moisture content at the maximum laboratory dry density.
2.30 RELATIVE COMPACTION - the degree of compaction (expressed as a percentage) of dry unit weight of a material as compared to the maximum laboratory dry unit weight of the material.
2.31 ROUGH GRADE - the ground surface configuration at which time the surface elevations approximately conform to the approved plan.
2.32 SITE - the particular parcel of land where grading is being performed.
2.33 SHEAR KEY - similar to buttress, however, it is generally constructed by excavating a slot within a natural slope in order to stabilize the upper portion of the slope without grading encroaching into the lower portion of the slope.
2.34 SLOPE - is an inclined ground surface the steepness of which is generally specified as a ratio of horizontal:vertical (e.g., 2:1).
2.35 SLOPE WASH - soil and/or rock material that has been transported down a slope by mass wasting assisted by run-off water not confined by channels (also see Colluvium).
I I I I I I I I I I I I I I I I I I I
Page 5
2.36 SOIL - naturally occurring deposits of sand, silt, clay, etc., or combinations thereof.
2.37 SOILS ENGINEER - licensed Civil Engineer experienced in soil mechanics (also see Geotechnical Engineer) .
2.38 STABILIZATION FILL - a fill mass, the configuration of which is typically related to slope height and is specified by the standards of practice for enhancing the stability of locally adverse conditions. A stabilization fill is normally specified by minimum key width and depth and by maximum backcut angle. A stabilization fill may or may not have a backdrainage system specified.
2.39 SUBDRAIN - generally a pipe and gravel or similar drainage system placed beneath a fill in the alignment of canyons or former drainage channels.
2.40 SLOUGH - loose, non-compacted fill material generated during grading operations.
2.41 TAILINGS ~ non-engineered fill which accumulates on or . . . adJacent to equipment haul-roads.
2.42 TERRACE - relatively level step constructed in the face of a graded slope surface for drainage control and maintenance purposes.
2.43 TOPSOIL - the presumably fertile upper zone of soil which is usually darker in color and loose.
2.44 WINDROW - a string of large rock buried within engineered fill in accordance with guidelines set forth by the Geotechnical consultant.
3.0 OBLIGATIONS OF PARTIES
3.1 The Geotechnical consultant should provide observation and testing services and should make evaluations to advise the Client on geotechnical matters. The Geotechnical Consultant should report his findings and recommendations to the Client or his authorized representative.
3.2 The Client should be chiefly responsible for all aspects of the project. He or his authorized representative has the responsibility of reviewing the findings and recommendations of the Geotechnical Consultant. He shall authorize or cause to have
I I I I I I I I I I I I I I I I I I I
Page 6
authorized the Contractor and/or other consultants to perform work and/or provide services. During grading the Client or his authorized representative should remain on-site or should remain reasonably accessible to all concerned parties in order to make decisions necessary to maintain the flow of the project.
3.3 The Contractor should be responsible for the safety of the project and satisfactory completion of all grading and other associated operations on construction projects, including, but not limited to, earth work in accordance with the project plans, specifications and controlling agency requirements. During grading, the Contractor or his authorized representative should remain on-site. overnight and on days off, the Contractor should remain accessible.
4,0 SITE PBEPABATION
4.1 The Client, prior to any site preparation or grading, should arrange and attend a meeting among the Grading Contractor, the Design Engineer, the Geotechnical Consultant, representative of the appropriate governing authorities as well as any other concerned parties. All parties should be given at least 48 hours notice.
4.2 Clearing and grubbing should consist of the removal of vegetation such as brush, grass, woods, stumps, trees, roots of trees and otherwise deleterious natural materials from the areas to be graded. Clearing and grubbing should extend to the outside of all proposed excavation and fill areas.
4.3 Demolition should include removal of buildings, structures, foundations, reservoirs, utilities (including underground pipelines, septic tanks, leach fields, seepage pits, cisterns, mining shafts, tunnels, etc.) and other man-made surface and subsurface improvements from the areas to be graded. Demolition of utilities should include proper capping and/or re-routing pipelines at the project perimeter and cut-off and capping of wells in accordance with the requirements of the governing authorities and the recommendations of the Geotechnical Consultant at the time of demolition.
4.4 Trees, plants or man-made improvements not planned to be removed or demolished should be protected by the Contractor from damage or injury.
I I I I I I I I I I I I I I I I I I I
Page 7
4,5 Debris generated during clearing, grubbing and/or demolition operations should be wasted from areas to be graded and disposed of off-site. Clearing, grubbing and demolition operations should be performed under the observation of the Geotechnical consultant.
4.6 The Client or Contractor should obtain the required approvals from the controlling authorities for the project prior, during and/or after demolition, site preparation and removals, etc. The appropriate approvals should be obtained prior to proceeding with grading operations.
5.0 SITE PROTECTION
5.1 Protection of the site during the period of grading should be the responsibility of the contractor. Unless other provisions are made in writing and agreed upon among the concerned parties, completion of a portion of the project should not be considered to preclude th.at portion or adjacent areas from the requirements for site protection until such time as the entire project is complete as identified by the Geotechnical Consultant, the Client and the regulating agencies.
5.2 The Contractor should be responsible for stability of all temporary excavations. Recommendations by the Geotechnical Consultant pertaining to temporary excavations (e.g., backcuts) are made in consideration of stability of the completed project and, therefore, should not be considered to preclude the responsibilities of the Contractor. Recommendations by the Geotechnical Consultant should not be considered to preclude more restrictive requirements by the regulating agencies.
5.3 Precautions should be taken during site clearing, excavating and grading to protect the work site from flooding, ponding or inundation resulting from poor or improper surface drainage. Temporary provisions should be made during the rainy season to adequately direct surface drainage away from and off the work site. Where low areas cannot be avoided, pumps should be kept on hand to continually remove water during periods of rainfall.
5.4 curing periods of rainfall, plastic sheeting should be kept reasonably accessible to prevent unprotected slopes from becoming saturated. Where necessary during periods of rainfall, the contractor should install
I I I I I I I I I I I I I I I I I I I
Page 8
checkdams, desilting basins, rip-rap, sand bags or other devices or methods necessary to control erosion and provide safe conditions.
5.5 During periods of rainfall, the Geotechnical Consultant should be kept informed by the Contractor as to the nature of remedial or preventative work being performed (e.g., pumping, placement of sand bags or plastic sheeting, other labor, dozing, etc.).
5.6 Following periods of rainfall, the contractor should contact the Geotechnical Consultant and arrange a walk-over of the site in order to visually assess rain related damage. The Geotechnical Consultant may also recommend excavations and testing in order to aid in his assessments. At the request of the Geotechnical Consultant, the Contractor shall make excavations in order to evaluate the extent of rain related-damage.
5.7 Rain~related damage should be considered to include, but may not be limited to, erosion, silting, saturation, swelling, structural distress and other adverse conditions identified by the Geotechnical Consultant.
Soil adversely affected should be classified as Unsuitable Materials. and should be subject to overexcavation and replacement with compacted fill or other remedial grading as recommended by the Geotechnical Consultant.
5.8 Relatively level areas, where saturated soils and/or erosion gullies exist to depths of 1 ft or greater, should be overexcavated to unaffected, competent material. Where less than 1 ft in depth, unsuitable materials may be processed in-place to achieve near-optimum moisture content, then thoroughly compacted in accordance with the applicable specifications. If the desired results are not achieved, the affected materials should be overexcavated, then replaced in accordance with the applicable specifications.
5.9 In slope areas, where saturated soils and/or erosion gullies exist to depths of 1 ft or greater, they should be overexcavated and replaced as compacted fill in accordance with the applicable specifications. Where affected materials exist to depths of less than l ft below proposed finished grade, remedial grading by moisture conditioning in-place, followed by thorough
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compaction in accordance with the applicable grading guidelines herein may be attempted. If the desired results are not achieved, all affected materials should be overexcavated and replaced as compacted fill in accordance with the slope repair recommendations herein. As field conditions dictate, other slope repair procedures may be recommended by the Geotechnical Consultant.
6.0 EXCAVATIONS
6.1 UNSUITABLE MATERIAL§
6.1.l Materials which are unsuitable should be excavated under observation and recommendations ofthe Geotechnical Consultant. Unsuitable materials include, but may not be limited to, dry, loose, soft, wet, organic compressible natural soils and fractured, weathered, soft bedrock and non-engineered or otherwise deleterious fill materials.
6.1.2 Material identified by the Geotechnical Consultant as unsatisfactory due to its moisture content should be overexcavated, watered or dried, as needed, and thoroughly blended to a uniform near optimum moisture content (as per guidelines, reference 7.2.1) prior to placement as compacted fill.
6.2 CUT SLOPES
6.2.l Unless otherwise recommended by the Geotechnical Consultant and approved by the regulating agencies, permanent cut slopes should not be steeper than 2:1 (horizontal:vertical).
6.2.2 If excavations for cut slopes expose loose, cohesionless, significantly fractured or otherwise unsuitable material, overexcavation and replacement of the unsuitable materials with a compacted stabilization fill should be accomplished as recommended by the Geotechnical Consultant. Unless otherwise specified by the Geotechnical Consultant, stabilization fill construction should conform to the requirements of the Standard Details.
6.2.3 The Geotechnical Consultant should review cut slopes during excavation. The Geotechnical
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consultant should be notified by the contractor prior to beginning slope excavations.
6.2.4 If, during the course of grading, adverse or potentially adverse geotechnical conditions are encountered, which were not anticipated in the preliminary report, the Geotechnical Consultant should explore, analyze and make recommendations to treat these problems.
6.2.5 When cut slopes are made in the direction of the prevailing drainage, a non-erodible diversion swale (brow ditch) should be provided at the top-of-cut.
6. 3 PAD ABEAS
6.3.l All pad areas, including side yard terraces, above stabilization fills or buttresses should be overexcavated to provide for a minimum of 3 ft (refer to standard Details) of compacted fill over the entire pad areas. Pad areas with both fill and cut materials exposed and pad areas containing both very shallow (less than 3 ft) and deeper fill should be overexcavated to provide for a uniform compacted fill blanket with a minimum thickness of 3 ft (refer to standard Details) . Cut areas exposing significantly varying material types should also be overexca.vated to provide for at least a 3 ft thick compacted fill blanket. Geotechnical conditions may require greater depth of overexcavation. The actual depth should be delineated by the Geotechnical Consultant during grading.
6.3.2 For pad areas created above cut or natural slopes, positive drainage should be established away from the tops-of-slopes. This may be accomplished utilizing a berm and/or an appropriate pad gradient. A gradient in soil areas away from the tops-of-slopes of 2% or greater is recommended.
7.0 COMPACTED FILL
All till materials should be compacted as specified below or by other methods specifically recommended by the Geotechnical Consultant. Unless otherwise specified, the minimum degree of compaction (relative compaction) should be
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90% of the maximum laboratory dry density as determined by ASTM Test Method D 1557,
7.1 PLACEMENT
7.1.1 Prior to placement of fill, the contractor should request a review by the Geotechnical consultant of the exposed ground surface. Unless otherwise recommended, the exposed ground surface should be scarified (6 in minimum), watered or dried as needed, thoroughly blended to achieve near optimum moisture content, then compacted to a minimum of 90% of the maximum laboratory dry density (ASTM D 1557). The review by the Geotechnical Consultant should not be considered to preclude inspection and approval by the governing agency.
7.1.2 Fill should be placed in thin horizontal lifts not exceeding 8-in in loose thickness prior to compaction. Each lift should be watered or dried as needed, thoroughly blended to achieve near optimum moisture content then compacted by mechanical methods to a minimum of 90% of the maximum laboratory dry density (ASTM D 1557). Each lift should be treated in a like manner until the desired finished grades are achieved.
7.1.3 The Contractor should have suitable and sufficient mechanical compaction equipment and watering apparatus on the job site to handle the amount of fill being placed in consideration of moisture retention properties of the fill materials. If necessary, excavation equipment should be "shut down" temporarily in order to permit proper compaction of fills. Earth moving equipment should only be considered a supplement and not substituted for conventional compaction equipment.
7.1.4 When placing fill in horizontal lifts adjacent to areas sloping steeper than 5:1 (horizontal:vertical), horizontal keys and vertical benches should be excavated into the adjacent slope areas. Keying and benching should be sufficient to provide at least 6 ft wide benches and a minimum of 4 ft of vertical bench height within firm natural ground, firm bedrock or engineered fill. No compacted fill should be placed in an area subsequent to keying
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and benching until the area has been reviewed by the Geotechnical Consultant. Material generated by the benching operation should be moved sufficiently away from the bench area to allow for the recommended review of the horizontal bench prior to placement of fill. Typical keying and benching details have been included within the accompanying Standard Details.
7.1.5 Within a single fill area where grading procedures dictate 2 or more separate fills, temporary slopes (false slopes) may be created. When placing fill adjacent to false slopes, benching should be conducted in the same manner as described above. At least a 3 ft vertical bench should be established within the firm core of adjacent approved compacted fill prior to placement of additional fill. Benching should proceed in at least 3 ft vertical increments until the desired finished grades are achieved.
7.l.6 Fill should be tested for compliance with the recommended relative compaction and moisture content. Field density testing should conform to ASTM Method of Test D 1556, D 2922 and/or D 2937. Tests should be prrvided for about every 2 vertical ft or l,000 yd of fill placed. Actual test interval may vary as field conditions dictate. Fill found not to be in conformance with the grading recommendations should be removed or otherwise handled as recommended by the Geotechnical Consultant.
7.1.7 The Contractor should assist the Geotechnical Consultant and/or his representative by digging test pits for removal determinations and/or for testing compacted fill.
7.1.B As recommended by the Geotechnical Consultant, the Contractor should "shut down" or remove grading equipment from an area being tested.
7.1.9 The Geotechnical consultant should maintain a plan showing approximate locations of field density tests. Unless the Client provides for actual surveying of test locations, the locations shown by the Geotechnical Consultant should only be considered rough estimates and should not be utilized for the purposes of preparing cross sections showing test locations
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or in any case for the purpose of after-the-fact evaluating of the sequence of fill placement.
7.2 MQISTQRE
7.2.l For field testing purposes, "near optimum moisture content" will vary with material type and other factors including compaction procedures. "Near optimum moisture content" may be specifically recommended in Preliminary Investigation Reports and/or may be evaluated during grading.
7.2.2 Prior to placement of additional compacted fill following an overnight or othe.r grading delay, the exposed surface or previously compacted fill should be processed by scarification, watered or dried as needed, thoroughly blended to near optimum moisture content, then recompacted to a minimum 90% of maximum laboratory dry density (ASTM D 1557). Where wet, dry or other unsuitable materials exist to depths of l ft or greater, the unsuitable materials should be overexcavated.
7.2.3 Following a period of flooding, rainfall or overwatering by other means, no additional fill should be placed until damage assessments have been made and remedial grading performed as described in Section 5.6, herein.
7.3 FILL MATERIAL
7.3.l Excavated on-site materials may be utilized as compacted fill provided they are free from trash, vegetation and other deleterious materials prior to placement and are approved by the Geotechnical consultant.
7.3.2 Where import materials are required for use on-site, the Geotechnical Consultant should be notified at least 48 hours in advance of importing, in order to sample and test materials from proposed borrow sites. No import materials should be delivered for use on-site without prior sampling, testing and approval by the Geotechnical Consultant.
7.3.3 Where oversized rock or similar irreducible material is generated during grading, it is
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reco1DJ11ended, where practical, to waste such material off-site or on-site in areas designated as "non-structural rock disposal areas". Rock placed in disposal areas should be placed with sufficient fines to fill voids. The rock should be compacted in lifts to an unyielding condition. The disposal areas should be covered with at least 3 ft of compacted fill which is free of oversized material. The upper 3 ft should be placed in accordance with the guidelines herein for compacted fill.
7.3.4 Rocks 12 in or less in maximum dimension may be utilized within compacted fill, provided they are placed in such a manner that nesting of the rocks are avoided. Fill should be placed and thoroughly compacted over and around all rocks. The amount of rock should not exceed 40% by dry weight passing the 3/4 in sieve size. The 12 in and 40% recommendations herein may vary as field conditions dictate.
7.3.5 During grading operations, rocks or similar irreducible materials greater than 12 in maximum dimension (oversized material), may be generated. These rocks should not be placed within compacted fill unless placed as reco1DJ11ended by the Geotechnical Consultant.
7.3.6 Where rocks or similar irreducible materials of greater than 12 in but less than 4 ft in maximum dimension are generated during grading, or otherwise desired to be placed within an engineered fill, special handling in accordance with the accompanying Standard Details is recommended. Rocks greater than 4 ft should be broken down or disposed of off~site. Rocks up to 4 ft maximum dimension should be placed below the upper 10 ft of any fill and should not be closer than 20 ft to any slope face. These recommendations could vary as locations of improvements dictate. Where practical, over-sized material should not be placed below areas where structures or deep utilities are proposed. Oversized material should be placed in windrows on a clean, overexcavated or unyielding compacted fill or firm natural ground surface. Select native or imported granular soils (SE ~ 30 or higher) should be placed and thoroughly flooded over and around all windrowed
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rocks, such that voids are filled. Windrows of oversized material should be staggered so that successive strata of oversized material are not in the same vertical plane.
The Contractor should be aware that the placement of rocks in windrows will significantly slow the grading operations and may require additional equipment and/or special equipment.
7.3.7 It may be possible to dispose of individual larger rocks as field conditions dictate and as recommended by the Geotechnical Consultant at the time of placement.
7.3.8 Material that is considered unsuitable by the Geotechnical consultant should not be utilized in the compacted fill.
7.3.9 During grading operations, placing and mixing the materials from the cut and/or borrow areas may result in soil mixtures which possess unique physical properties. Testing may be required of samples obtained directly from the fill areas in order to verify conformance with the specifications. Processing of these addit.ional samples may take 2 or more working days. The Contractor may elect to move the operation to other areas within the project, or may continue placing compacted fill pending laboratory and field test results. should he elect the second alternative, fill placed is done so at the Contractor's risk.
7.3.10 Any fill placed in areas not previously reviewed and evaluated by the Geotechnical Consultant, and/or in other areas, without prior notification to the Geotechnical Consultant may require removal and recompaction at the Contractor's expense. Determination of overexcavations should be made upon review of field conditions by the Geotechnical Consultant.
7.4 FILL SLQPES
7.4.1 Unless otherwise recommended by the Geotechnical Consultant and approved by the regulating agencies, permanent fill slopes should not be steeper than 2:1 (horizontal:vertical).
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7.4.2 Except as specifically recommended otherwise or as otherwise provided for in these grading guidelines (reference 7.4.3), compacted fill slopes should be overbuilt and cut back to grade, exposing the firm, compacted fill inner core. The actual amount of over-building may vary as field conditions dictate. If the desired results are not achieved, the existing slopes should be overexcavated and reconstructed under the guidelines of the Geotechnical Consultant. The degree of overbuilding shall be increased until the desired compacted slope surface condition is achieved. Care should be taken by the contractor to provide thorough mechanical compaction to the outer edge of the overbuilt slope surface.
7.4.3 Although no construction procedures produce a slope free from risk of future movement, overfilling and cutting back of slope to a compacted inner core is, given no other constraints, the most desirable procedure. Other constraints, however, must often be considered. These constraints may include property line situations, access, the critical nature of the development and cost. Where such constraints are identified, slope face compaction may be attempted by conventional construction procedures including backrolling techniques upon specific recommendation by the Geotechnical Consultant.
As a second alternative for slopes of 2:1 (horizontal:vertical) or flatter, slope construction may be attempted as outlined herein. Fill should be placed in 6 to 8 in thick loose lifts. Each lift should be moisture conditioned and thoroughly compacted. The desired moisture content should be maintained and/or re-established, where necessary, during the period between successive lifts. Selected lifts should be tested to ascertain that desired compaction is being achieved. care should be taken to extend compactive effort to the outer edge of the slope. Each lift should extend horizontally to the desired finished slope surface or more as needed to ultimately establish desired grades. Grade during construction should not be allowed to roll off
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at the edge of the slope. It may be helpful to elevate slightly the outer edge of the slope. Slough resulting from· the placement of individual lifts should not be allowed to drift down over previous lifts. At intervals not exceeding 4 ft in vertical slope height or the capability of available equipment, whichever is less, fill slopes should be thoroughly backrolled utilizing a conventional sheepsfoot-type roller. Care should be taken to maintain the desired moisture content and/or re-establishing same as needed prior to backrolling. Upon achieving final grade, the slopes should again be moisture conditioned and thoroughly backrolled. The use of a side-boom roller will probably be necessary and vibratory methods are strongly recommended. Without delay, so as to avoid (if possible) further moisture conditioning, the slopes should then be grid-rolled to achieve a relatively smooth surface and uniformly compact condition.
In order to monitor slope construction procedures, moisture and density tests will be taken at regular intervals. Failure to achieve the desired results will likely result in a recommendation by the Geotechnical Consultant to overexcavate the slope surfaces followed by reconstruction of the slopes utilizing overfilling and cutting back procedures and/or further attempt at the conventional backrolling approach. Other recommendations may also be provided which would be commensurate with field conditions.
7.4.4 Where placement of fill above a natural or a cut slope is proposed, the fill slope configuration as presented in the accompanying Standard Details should be adopted.
7.4.5 For pad areas above fill slopes, positive drainage should be established away from the tops-of-slopes. This may be accomplished utilizing berm and pad gradients of at least 2% in soil areas.
7.5 OFF-SITE FILL
7.5.1 Off-site fill should be treated in the same manner as recommended in these specifications
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for site preparation, excavation, drains, compaction, etc.
7.5.2 Off-site canyon fill should be placed in preparation for future additional fill, as shown in the accompanying standard Details.
7.5.3 Off-site fill subdrains temporarily terminated (up canyon) should be surveyed for future relocation and connection.
8 • 0 QRAINAGE
8.1 canyon subdrain systems specified by the Geotechnical Consultant should be installed in accordance with the standard Details.
8.2 Typical subdrains for compacted fill buttresses, slope stabilizations or sidehill masses, should be installed in accordance with the specifications of the accompanying Standard Details.
8.3 Roof, pad and slope drainage should be directed away from slopes and areas of structures to suitable disposal areas via non-erodible devices, i.e., gutters, downspouts, concrete swales.
8.4 For drainage over soil areas immediately away from structures, i.e. within 4 ft, a minimum of 4% gradient should be maintained. Pad drainage of at least 2% should be maintained over soil areas. Pad drainage may be reduced to at least 1% for projects where no slopes exist, either natural or man-made, of greater than lo ft in height and where no slopes are planned, either natural or man-made, steeper than 2:1 (horizontal:vertical) slope ratio.
8.5 Drainage patterns established at the time of fine (precise) grading should be maintained throughout the life of the project. Property owners should be made aware that altering drainage patterns can be detrimental to slope stability and foundation performance.
9.0 STAKING
9.1 In all fill areas, the fill should be compacted prior to the placement of the stakes. This, particularly, is important on fill slopes. Slope stakes should not be placed until the slope is thoroughly compacted
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(back-rolled). If stakes must be placed prior to the completion of compaction procedures, it must be recognized that they will be removed and/or demolished at such time as compaction procedures resume.
9,2 In order to allow for remedial grading operations, which could include overexcavations or slope stabilization, appropriate staking offsets should be provided. For finished slope and stabilization backcut areas, we recommend at least 10 ft setback from proposed toes and tops-of-cuts.
10.0 SLOPE MAINTENANCE
10.1 Landscape Plants
In order to enhance surficial slope stability, slope planting should be accomplished at the completion of grading. Slope planting should consist of deep-rooting vegetation requiring little watering. Plants native to the southern California area and plants relative to native plants are generally desirable. Plants native to other semi-arid and arid areas may also. be appropriate. A Landscape Architect would be the best party to consult regarding actual types of plants and planting configuration.
10.2 Irrigation
10.2.l Irrigation pipes should be anchored to slope faces, not placed in trenches excavated into slope faces.
10.2.2 Slope irrigation should be minimized. If automatic timing devices are utilized on irrigation systems, provisions should be made for interrupting normal irrigation during periods of rainfall.
10.2.3 Though not a requirement, consideration should be given to the installation of near surface moisture monitoring control devices. Such devices can aid in the maintenance of relatively uniform and reasonable constant moisture conditions.
10.2.4 Property owners should be made aware that over-watering of slopes is detrimental to slope stability.
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10.3 Maintenance
10.3.l Periodic inspections of landscaped slope areas should be planned and appropriate measures should be taken to control weeds and enhance growth of the landscape plants. Some areas may require occasional replanting and/or reseeding.
10.3.2 Terrace drains and downdrains should be periodically inspected and maintained free of debris. Damage to drainage improvements should be repaired immediately.
10.3.3 Property owners should be made aware that burrowing animals can be detrimental to slope stability. A preventative program should be established to control burrowing animals.
10.3.4 As a precautionary measure, plastic sheeting should be readily available, or kept on hand, to protect all slope areas from saturation by periods of heavy or prolonged rainfall. This measure is strongly recommended, beginning with the period of time prior to landscape planting.
10.4 Repairs
10.4.l If slope failures occur, the Geotechnical consultant should be contacted for a field review of site conditions and development of recommendations for evaluation and repair.
10.4.2 If slope failures occur as a result of exposure to periods of heavy rainfall, the failure area and currently unaffected areas should be covered with plastic sheeting to protect against additional saturation.
10.4.3 In the accompanying standard Details, appropriate repair procedures are illustrated for superficial slope failures, i.e., occurring typically within the outer l ft to 3 ft ± of a slope face.
11.0 TRENCH BACKFILL
11.l Utility trench backfill should, unless otherwise recommended, be compacted by mechanical means. Unless otherwise recommended, the degree of compaction should
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be a minimum of 90% of the maximum laboratory dry density (ASTM D 1557).
11.2 As an alternative, granular material (sand equivalent greater than 30) may be thoroughly jetted in-place. Jetting should only be considered to apply to trenches no greater than 2 ft in width and 4 ft in depth. Following jetting operations, trench backfill should be thoroughly mechanically compacted and/or wheel-rolled from the surface.
11.3 Backfill of exterior and interior trenches extending below a 1:1 projection from the outer edge of foundations should be mechanically compacted to a minimum of 90% of the maximum laboratory dry density (ASTM D 1557) •
11.4 Within slab areas, but outside the influence of foundations, trenches up to 1 ft wide and 2 ft deep may be backfilled with sand and consolidated by jetting, flooding or by mechanical means. If on-site materials are utilized, they should be wheel-rolled, tamped or otherwise compacted to a firm condition. For minor interior trenches, density testing may be deleted or spot testing may be elected if deemed necessary, based on review of backfill operations during construction.
11.5 If utility contractors indicate that it is undesirable to use compaction equipment in close proximity to a buried conduit, the contractor may elect the utilization of light weight mechanical compaction equipment and/or shading of the conduit with clean, granular material, which should be thoroughly jetted in-place above the conduit, prior to initiating mechanical compaction procedures. Other methods of utility trench backfill compaction may also be appropriate, upon review by the Geotechnical consultant at the time of construction.
11.6 In cases where clean granular materials are proposed for use in lieu of native materials or where flooding or jetting is proposed, the procedures should be considered subject to review by the Geotechnical Consultant.
11.7 Clean granu1ar backfill and/or bedding are not recommended in slope areas unless provisions are made for a drainage system to mitigate the potential build-up of seepage forces.
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12.0 STATUS OF GBADING
Prior to proceeding with any grading operation, the Geotechnical Consultant should be notified at least 2 working days in advance in order to schedule the necessary observation and testing services.
12.l Prior to any significant expansion or cut back in the grading operation, the Geotechnical Consultant should be provided with adequate notice, i.e., 2 days, in order to make appropriate adjustments in observation and testing services.
12.2 Following completion of grading operations and/or between phases of a grading operation, the Geotechnical Consultant should be provided with at least 2 working days notice in advance of commencement of additional grading operations.
I I I I I I I I APPENDIX E
I PLATES 1, 2 and 3
I I I I I I I I I I
OVERSIZED -·~. -. -DOCUMENT HAS
,;;.· ..
BEEN PULLED AND SCANNED . WITH THE MAP
FILE.
... '
'
. •
. . . '
. . '
·-
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ADDENDUM TO PRELIMINARY GEOTECHNICAL AND FAULT HAZARD INVESTIGATION
1.4± Acre Commercial Development 25217 Jefferson Avenue,
Murrieta Area of Riverside County, California
In Response to County Review Dated September 11, 1990
PREPARED FOR
TRIPOINTE PROPERTIES, INC. 28691 Peach Blossom
Mission Viejo, California 92692
PREPARED BY
ICG INCORPORATED 1906 Orange Tree Lane, Suite 240
Redlands, California 92374
JOB NO: 08-8313-ool-Ol-01 LOG NO: 0-4411
SEPTEMBER 27, 1990
I I ICG
'" inccnporated
I Inland Empire Office= 1906 Oranga Tree Lane, Suite 240 Redlands, CA 92374
I 7141792-4222 fax: 7141798-1844
I I
Corporate Office: 5 Mason lrvine, CA 92718 714/951-8686 fax: 714195f-6813
San Diego County Office: 9240 Trade Place, Suite 100
I San Diego, CA 92126 6191536-1102 fax: 6191536-1306
Orange County Offica:
I 15Ma!::ion Irvine, CA 92718 714/951-8686
I I I I I I I I I
fax: 7141951-7969
September 27 1 1990
Tripointe Properties, Inc. 28691 Peach Blossom
Job No: 08-8313-001-01-01 Log No: 0-4411
Mission Viejo, California 92692
Attention:
SUBJECT:
REFERENCE:
Gentlemen:
Mr. Rodney L. Dubois
ADDENDUM TO PRELIMINARY GEOTECHNICAL AND FAULT HAZARD INVESTIGATION 1.4± Acre Commercial Development 25217 Jefferson Avenue, Murrieta Area of Riverside county, California In Response to County Review Dated September 11, 1990
"Preliminary Geotechnical and Fault Hazard Investigation 1.4± Acre Commercial Development 25217 Jefferson Avenue, Murrieta Area of Riverside County, California Job No: 08-8313-001-01-00 Dated July 3, 1990 Log No: 0-4241
This addendum is in response to Riverside County Planning Department's review letter of September 11, 1990 of the subject report. The comments in the review letter along with our responses are presented below:
Comment 1: The map shown in Figure 3 is not oriented as indicated by the north arrow provide.
Response: A revised Figure 3 is provided as an enclosure to this addendum.
Comment 2: Please clarify how you determined the potential groundwater level at the site. From the information provided on pages 10 and 11, it appears that the data is insufficient for such an extrapolation. It would be
Geotechnical Services, Construction Inspection and Tasting
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Tripointe Properties, Inc. September 27, 1990
Job No: 08-8313-001-0l-Ol Log No: 0-4411 Page 2
helpful if the wells mentioned were plotted on a site location map.
Response: The potential depth to groundwater below the surface of the site was extrapolated from the closest well (approximately 200 ft northwest of the site) tor which published information could be found (Well No. 7S/3W 2103). Data for other wells appeared inappropriate because they were likely separated from the site by groundwater barriers. Estimates of the depth to groundwater below the surface of the site were made by extrapolating the elevations of the groundwater levels recorded in the well northwest of the site (Well No. 7S/3W 2103). This extrapolation indicates groundwater may have been approximately 36 ft below the surface of the site in 1953 and approximately 54 ft below the surface of the site in 1958. This appears to be a reasonable extrapolation since that well was/is relatively close to the site (200± ft) .
The available data was for the years 1953-1958; therefore, groundwater conditions may presently be different at the site. More recent well records were reviewed in order to determine what changes may have taken place. The information reviewed indicated there was a general lowering of the groundwater table with as much as a 60 ft decline between 1953 and 1975. This lead to an estimate that the present depth to groundwater is likely no less than the previously recorded lc"'v'Cls and i:; "likely greater thc:ir-1 SO ft'' below the surface of the site.
The extrapolations and assumptions made in the estimation of the depth to groundwater at the site appear to us to be reasonable. A more detailed analysis may have been appropriate if the site were underlain by materials susceptible to liquefaction. The Unnamed Sandstone is a well consolidate Pleistocene deposit and is not in our opinion susceptible to liquefaction.
Comment 3: Provide clarification regarding inconsistencies in descriptions and lateral continuity of units between logs for Trench 1 and Trenches 2 and 3.
Response: Inconsistencies exist between the logs of Trench 1 and Trenches 2 and 3 because they were logged by different
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Tripointe Properties, Inc. September 27, 1990
Job No: 08-8313-001-01-01 Log No: 0-4411 Page 3
geologists (page 18). Trench 1 was logged by Project Geologist, Andy Price, and was field checked by Associated Geologist, Gerald J. Grimes (CEG 1144), as well as being inspected by Mr. Steve Kupferman and Ms. w.-Williams. Trenches 2 and 3 were logged by Mr. Grimes. The description of the units are not readily correlated between these sets of trench logs, but different geologist may describe the same unit differently. In our opinion, a geologist description should not be modified in order to be consistent with another description unless circumstances warrant such. since the objective of the trenching was achieved; that is to find continuous unfaulted units, consistency of the descriptions between Trenches l and Trenches 2 and 3 does not appear to be necessary.
comment 4: Please identify the difference between "paleogenic soil" and ''pedogenic soil'' on your Plates 2 and 3, respectively.
Response: This is an incorrect spelling on Plate 2. The correct spelling is pedogenic soil. A corrected copy of Plate 2 is provided as an enclosure to this addendum.
comment 5: The extent of your recommended setback zones should be clearly indicated.
Response: The extent of our setback zones is from the "approximate limits of restricted use setback for human occupancy structures" to the northeast and southwest property lines. The area between the "approximate limits of restricted use setback for human occupancy structures" is suitable for human occupancy structures. The area that has restricted uses, and is not suitable for human occupancy structures without further investigation, is shown with hachured lines on the enclosed revised Plate 1.
Comment 6: Discuss the age of the fault encountered at station 1+85 in Trench 1. Also indicate the potential for sympathetic movement along this fault during an earthquake on the nearby Wildomar fault.
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Tripointe Properties, Inc. September 27, 1990
Response:
Job No: 08-8313-001-ol-Ol Log No: 0-4411 Page 4
"An offset of bedding was suspected to exist at approximately station 1+85." (page 19, paragraph 2, line 1). "Due to the relatively gradational contacts, the suspected displacement of the bedding could not be confirmed." (page 19, paragraph 2, line 5). Trench 2 was placed across the trend of the suspected fault at Station 1+85 in Trench l in order to better define the origin of the suspected displacement of bedding. No beds were observed to be displaced in that trench and no faults crossed that trench. Therefore, a discussion of the age of and/or potential for sympathetic movement on a feature that was not determined to be a fault does not appear appropriate.
Comment 7: The "irregularity in bedding" mentioned on page 19/paragraph 3 is not annotated on your Trench 2 log.
Response: The log for Trench 2 illustrates an "irregularity in bedding" by a slightly wavy contact between units 3 and 4 in the Unnamed Sandstone. This ''irregularity in bedding'' is annotated on the enclosed revised log of Trench 2 as "sharp wavy contact".
Comment 8: Discuss the potential for the secondary seismic hazards of landsliding, earthquake-induced flooding and seiche at this site.
Response;
Earthquake-Induced Landsliding
The potential for earthquake induced landslides increases in direct relationship with proximity to causative fault, seismic moment of the earthquake and relative slope steepness (greater with slopes steeper than 25 degrees) . The exception to this is lateral spreads which generally are the result of liquefaction.
No slopes exist on-site which are steeper than approximately 5 degrees; therefore, earthquake induced landslides are not likely. Liquefaction is not anticipated to occur on-site; therefore, lateral spreading is not likely.
I I I I I I I I I I I I I I I I I I I
Tripointe Properties, Inc. September 27, 1990
Earthquake-Induced Flooding
Job No: OB-8313-001-01-01 Log No: 0-4411 Page 5
No large above-ground tanks presently exist up slope in the immediate vicinity of the site; therefore, flooding due to tank failure is unlikely.
A tsunami is a large wave commonly called a tidal wave. It is generally restricted to very large bodies of water; such as oceans. The likelihood tor a tsunami effecting the site is nil.
Seiche is an earthquake-induced wave in a lake or reservoir. Since no large lakes or reservoirs, presently exist in the immediate vicinity of the site, the likelihood of seiche effecting the site is nil.
Flooding due to dam failure is not likely. Lake Skinner, Canyon Lake and Lake Elsinore all exist in the general area, but none are close enough to be suspected as being sources of significant flooding in the immediate area of the site. Development in the general area has included several golf course ponds. It does not appear that those ponds will effect the site.
We hope these responses will be adequate for the completion of the Riverside County Planning Department's review of this project. If there are any other questions, please call.
Very truly yours,
ICG Incorporated Inc. Inland Empire Division
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Gerald J. Grimes, CEG 1144 Associate Geologist Registration Expires 6-30-92
Enclosures:
Distribution:
Figure 3 Plate 1 Plate 2 Plate 3
(Revised) (Revised) (Revised) (Revised)
(2) Addressee (6) Riverside County Planning Department
Attention: Steven Kupferrnan
I I I I I I I I I I I I I I I I I I I
UNITS
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Ops PAUBA FORMATION
QUI UNNAMED SANDSTONE
SYMBOLS
- - - ~ GEOLOGIC CONTACT
LOG NO, 0-011
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FAULT, SOLID WHERE CONFIRMED ,DASHED WHERE
INFERRED DOTTED WHERE CONCEALED - .....,
I NOi CATES A SHEAR ZONE L INDICATES LATE
PLEISTOCENE FAULTING
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BEDDING ATTITUDE
VERTICAL JO..iT STRIKE SCALI! 1'•2000"
-11~ GROUNDWATE:R CONTOURS IN METERS ( Rli'ftl!DI
GEOLOGIC MAP OF THE ELSINORE FAULT ZONE MODIFIED FROM KENNEDY 1977
JOB NO: 07,-8313-001-01-01 DATE: SEPTEMBER 1990 ~IGURE: 3
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