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

I I I I I I I I I I I I I I I I I I I

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


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


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



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.



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



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 .

I I I I I I

\ . . ' :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'


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

" .

W'''''A ... ,,,, .. ,.,_..,,_ ~·--· ·-·--·-·---· ----·--··---·- .... , ... ·-' .. ,

- - -

•Cl" U-~· OI' J& .. Ul'lihNl•'ll ...... 1111.Lt TO- -••I llN I~-·~

~ ...... ,.I a I- H. LOC:nt9•1 lflt' 1nc111n1111 ..,...,. ....... Loc: .. uon ... __ _,., .. lilltOll•••• f'llll

,.._ "" um•-•• ..

•

\

... ·

- -.... .

•

..... , .... ~ .... _.~~~

- - - - - -~ ....

MAP OF HISTORIC EARTHQUAKE EPICENTERS, MAGNITUDE > 5.0 JOB NO.:

07-8313-001-00-00 DATE: JULY 1990 FIGURE:

2

- - - -.... ______ _.

..., ....

• .... ?:> --!!S~ :-



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.



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


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



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


-' ,·,

' ·--· --- Jr

_) I\ "< (~ --···' ( ·- '

' I C:.l ···.,_)

-·--EXPLANATION

AEIUAL PHOTOORAPH LINl!AMENT

LINEAR COLOR CONTRAST

• •

=-~~"~v' '-? I ,}

- )

(/, I

/

. ·• Windmill\

"'·"\ (_~ ..

• '

"·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



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



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



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




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:




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.



Job No: 08-8313-001-00-00 Log No: 0-4241 Page 15

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)

Job No: 08-8313-001-00-00

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



Job No: 08-8313-001-oo-oo Log No: o-4241 Page 16

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




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



Job No: 08-8313-001-00-00 Log No: 0-4241 Page 18

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



Job No: 08-8313-001-00-00 Log No: 0-4241 Page 19

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



Job No: 08-8313-001-00-00 Log No: 0-4241 Page 20

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




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).



Job No: 08-8313-001-00-00 Log No: 0-4241 Page 22

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.



7.2.2 Site Preparation

Job No: 08-8313-001-00-00 Log No: 0-4241 Page 23

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


Tripointe Properties, Inc. 3uly 3, 1990

Job No: 08-8313-001-00-00 Log No: 0-4241 Page 24

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%




Job No: 08-8313-001-00-00 Log No: 0-4241 Page 25

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



Job No: 08-8313-001-00-00 Log No: 0-4241 Page 26

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




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.




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



Job No: 08-8313-001-00-00 Log No: 0-4241 Page 29

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%


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.



Job No: 08-8313-001-00-00 Log No: 0-4241 Page 30

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:



Job No: 08-8313-001-00-00 Log No: 0-4241 Page 31

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



Job No: 08-8313-001-00-00 Log No: 0-4241 Page 32

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



Job No: 08-8313-001-00-00 Log No: 0-4241 Page 33

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.



Job No: 08-8313-001-00-oo Log No: 0-4241 Page 34

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

I I I I I I I I I I I


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;


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;


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:

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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:

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r - ·r -. • ' • ' . ' ' . . . . X,~ 1 I ' ' ' I . ' . ~ I ' • ' ' ' I . . .

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RING I x- - ~ ]: r

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RING 'RING - . ... SAMPLE SAMPLE - .

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-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


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


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


APPENDIX D

STANDARD GUIDELINES FOR GRADING PROJECT


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.


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


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


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).


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


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.


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


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


Page 9

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


Page 10

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


Page 11

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


Page 12

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


Page 13

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


Page 14

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


Page 15

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).


Page 16

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


Page 17

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


Page 18

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


Page 19

(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.


Page 20

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


Page 21

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.


Page 22

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.

... '

'

. •

. . . '

. . '

·-


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


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


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


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



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.



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.



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

c ·-.I:\ - _\_'-~.._~--- '"--,\;~~:\'::~~----)('. ~·~-··-.-"

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


UNITS

Qal All.UVIJ M

Ops PAUBA FORMATION

QUI UNNAMED SANDSTONE

SYMBOLS

- - - ~ GEOLOGIC CONTACT

LOG NO, 0-011

1~

-e--

FAULT, SOLID WHERE CONFIRMED ,DASHED WHERE

INFERRED DOTTED WHERE CONCEALED - .....,

I NOi CATES A SHEAR ZONE L INDICATES LATE

PLEISTOCENE FAULTING

.,.

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

ICQ INCOl!POAATE:D-INLAND EMl'IRl!DIVl8ION'

ingmw.consrv.ca.gov/shp/apsi_siteinvestigationreports_ocr/... · 1990-07-03 · state of...

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