<

STATE or (.AL!FORNIA.-··H\[ Rt-SOURCE'S AGENCY ===:: "·::.=: . ·.-. -----:: ... ===-----===

DH'ARTM(N\ OF (()N~f.RVAT!ON

DIVISION OF MINES AND GEOLOGY BAY AREA R[GIOMAL OfFICE .'.tf!O CIVIC DR!VE, su1n: 100

F'lfASANT 111ll., CA 94~23-1997

PHONE: (-ll.5) 671-4910

Anthony B. Brown Engin~erinn Gc.~oloe i st Rlv1~rside CounLy Plannlne DcpartH1ent 4080 Lemon Streot, 9th Floor Rivecsidb, California 9l501

D"ar Tony:

We ;ire pln(:lng on open file the following report, rcv.lewed and nppr0v:~<l by Ll1c County of Riverside in compliance wit11 the Alq1Jlst-·Priolo Sp~cial Studies Zones Act:

cc:

Detnil~d fault investigation, propoi;ed development, Estes A, Palomnr <in<l Central Stre:els, Wi.ldoma.r, Riverside Cout1ty, L.A., by G,A. Nicoll & Aosoc.; J11ly 6, 1981,Cotinty Report GR-·309

A-P fileV

Sincerely,

/

EARL W. HART Senior Geologist

GEORGE DEUKME J1AN, C'>oveo1r1or

October 3., 1984

G. A. Ni co 11 and Assoc., Inc. 14712 Sinclair Circle Tustin, CA 92680

Attn: John F. Dablow, III and Grayson R. Walker

Gentlemen:

"i--'/... ,,.!_.

. ·-····' --~----~-·~··-·-·-~

·····--~~-~ . ........___ ... ,,,_,~--- ... ,~-~--- __ ,, __ _ - n·- --- • • ~••

SUBJECT: Project R2411 Plot Plan 7889 County Geologic Report 309 Andrew Joncich & Associates Proposed Post Office - Wildomar

We have reviewed your report entitled, "Detailed Fault Investigation, Proposed Development, Estes "A", Palomar and Central Streets, Wildomar, Riverside County, California," dated July 6, 1981, for Turner Realty. Your report determined that:

1. Based upon review of aerial photographs and geophysical surveying, it is believed that the Wildomar Fault crosses the site. However, trenching did not reveal evidence for Holocene movement on the fault, therefore, the fault is classified as only potentially active and not precisely located. Based upon these evaluations, the potential for a major earthquake occur­ring along the Wildomar Fault at this site is low.

2. It is feasible that a Richter Magnitude 6.0 earthquake may occur in the Lake Elsinore area. An earthquake of this magnitude could be expected to produce a peak ground acceleration of 0.58g at the site, and a site period of 0.19 and 0.26 seconds.

Your report recommended that:

1. No bui.lding setback should be required from the Wildomar Fault.

2. Structures should be designed to resist strong ground shaking from a Richter Magnitude 6.0 earthquake occurring in the Lake Elsinore area.

3. A lower limiting value for the site period should be 0.5 seconds.

It is our opinion that the report was performed in a competent manner consistent with the present "state-of-the-art'' and satisfies the requirements of the Alquist­Priolo Special Studies Zone Act and the associated Riverside County Ordinance· No. 547. Final· approval of the report is hereby given. · ·

4080 LEMON STREET, 91" FLOOR RIVERSIDE, CALIFORNIA 92501

46-209 OASIS STREET, ROOM 304 INDIO, CALIFORNIA 92201

(619)342·8277

G. A. Nicoll and Assoc., Inc. -2- October 3, 1984

It should be noted that this geologic report was prepared for a larger parcel which includes the subject p 1 ot pl an. The proposed post office wi 11 be constructed approximately 120 feet southerly of the postulated buried trace of the Wildomar Fault and would not be expected to be affected if ground rupture were to occur along the fault as shown on Figure No. 4 in the report. Therefore, we have no recommendations or restrictions in addition to those made in the report.

Very truly yours,

RIVERSIDE COUNTY PLANNING DEPARTMENT Roge -~eter, Plannin Director

___ !} .. . (J/ . / nthony B. Br91"n, '· . Engineering Geologist - CEG - 901

ABB:dla cc: Earl w. Hart, Sr. Geo. CDMG, S.f.'

Building and Safety, Attn; Bill Harvey (2) Andrew Joncich, A.I.A. and Assoc. Trip Hord - Team 2

G. A. Nicoll and Associates, Inc.

Earth Science Consultants

July 6, 1961 Project R2411

Turner Realty Investment Division 41710 Ivy Street Murrieta, California 92362

Attention: Mr. Ron Parks

. '

Subject: Detailed Fault Investigation Proposed Development, Estes "A" Palomar and Central Streets Wildomar, Riverside County, California

Gentlemen:

This report presents the results of our detailed fault investi­gation. for the proposed development located north of the inter­section of Palomar and Central Streets, in the community of Wildomar, in Riverside County, California.

The project site consists of approximately 21 acres of land to be developed as residential and commercial sites. Grading and building plans are not available at this time. Our study indicates that it is geotechnically feasible to develop the entire site.

The project site lies within an Alquist-Priolo Special Studies zone related to the Wildomar fault segment of the Elsinore fault zone. A correlation of geophysical data, geomorphic evidence and photographic analyses indicates that the Wildomar fault transects the property at depth. However, based on our fault trench examinations, no evidence was found which would substant­iate the presence of active fault breaks in the materials encountered. Therefore, we feel that no fault setbacks will be required at the site.

The general findings, conclusions and recommendations of this investigation are included in the report which follows. Also included is a report of trench compaction testing.

14712 Sinclair Circle. Tustin, California 92680 (714) 731·2680

..

Turner Realty Project R2411 July 6, 1981 Page Two

We appreciate the opportunity to be of continued service. lf you have any questions, or if we can be of further assistance, please call.

Very truly yours,

G. NICOLL AND ASSOCIATES, INC.

~€/-f;!?,/~ . Gerald A. Nic;11f"'- - -~ President

GAN/GDii:bjd

I [

1.

2.

3.

4.

5.

6.

7.

8.

Project R2411

DETAILED FAULT INVESTIGATION

PROPOSED DEVELOPMENT, ESTES "A"

PALOMAR AND CENTRAL STREETS

WILDOMAR, RIVERSIDE COUNTY, CALIFORNIA

TABLE OF CONTENTS

INTRODUCTION

PROJECT DESCRIPTION

PURPOSE OF THE INVESTIGATION

SCOPE

FIELD WORK/LABORATORY TESTING

FIELD INVESTIGATION

LABORATORY TESTING

TRENCH BACKFILL COMPACTION AND TESTING

SURFACE CONDITIONS

GEOLOGY

FINDINGS

8.1 Geologic Setting

8.2 Structural Geology

8.3 Soil and Bedrock units

8,4 Ground Water

PAGE

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2

3

3

4

4

4

5

5

6

I

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9.

10.

11.

12.

13.

SEISMICITY

FAULT HAZARD INVESTIGATION

10.l General

10.2 Research and Photographic Evaluation

10.3 Preliminary Fault Trenching

10.4 Geophysical Survey

10.5 Final Fault Trench Examination

CONCLUSIONS AND RECOMMENDATIONS

CONCLUSIONS

RECOMMENDATIONS

LIMITATIONS

REFERENCES

GEOPHYSICAL SURVEY

APPENDICES

FAULT TRENCH INVESTIGATION

----------· -·· ---- -- .

Table of Contents Project R2411 Page Two

PAGE

7

8

8

9

10

10

11

12

lJ

Appendix

A

B

c

LABORATORY AND TRENCHING COMPACTION TESTING D

FIGURES

Location Map

Seismicity Map

Location Map for Special studies Zone

Geologic Map

Geologic Cross Section

Unified Soil Classification System

Trench Cross Sections

Trench T-1

Trench T-2

Trench T-3

Trench T-4

I TABLES

summary of Field Density Tests

..

Figure

1

2

3

4

5

6

7 - 12

13 & 14

15

16

Table of Contents Project R2411 Page Three

Location

Following

Following

Following

Following

Following

Appendix C

Appendix C

Appendix c

Appendix c

Appendix C

Pg,

Pg,

Pg.

Pg.

Pg.

Table 'Location

1

7

8

13

13

I Appendix D

=

Project R2411

DETAILED FAULT INVESTIGATION

PROPOSED DEVELOPMENT, ESTES "A"

PALOMAR AND CENTRAL STREETS

WILDOMAR, RIVERSIDE COUNTY, CALIFORNIA

INTRODUCTION

1. PROJECT DESCRIPTION

1.1 The project site is located north of the intersection of Palomar and Central Streets in Wildomar, Riverside County, California. The site covers about 21 acres, which is proposed to be subdivided into residential and commercial lots. We understand that the 3.1 acre block of land at the northwest end of the site, adja­cent to the cemetery, may be donated to the local cemetery district. The geographic relationships are shown on the Location Map, Figure 1.

1.2 The property is legally defined as Estes "A", being a portion of Lot 27, l'llock "C" as shown on Parcel Maps "K", "L", and "M", Elsinore, per Map Book 4/74, Records of San Diego County; also being a portion of the Sl/2 of Section 35, T.6S., R.4W., SBB and Mand partly in Rancho La Laguna. The Assessors Parcel Number is 369-060-007 and 008,

2, PURPOSE OF THE INVESTIGATION

The prima.r.y purpose of this investigation was to locate the Wildomar fault at the site and to determine if any active fault breaks are present. The general soil and geologic features, and the site seismicity were also included as part of this study.

3. SCOPE

The scope of services provided in this investigation included:

a) Review of previous soil engineering and geologic work in the area, including published and unpublished reports and maps.

,. _\

"''--------------------------------.

:woo 0 - -

\ . ' . '

2000 4000 -- -Base Map: USGS Wildomar Quadrangle/ 7.S minute series1 1973

G. A. NICOLL Ii ASSOCIATES, INC. 14lTH ICIU.:I CllNIULTAHT$

Estes 11

Dal•: July, 1981

Fro;ect No~ 2411 Fip• No' 1

..

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Turner Realty Project R2411 July 6, 1981 Page Two

4.

b) Analyses of stereoscopic pairs of aerial photographs to evaluate the topography and geologic structure from a three-dimensional perspective.

cl A geophysical investigation at the site including seismic, magnetic and gravity surveys to locate and define the nature of the Wildomar1fault.

:1 (.:

d) Subsurface exploration, including 1,020 feet of trench excavated by a tractor-mounted backhoe.

e) Detailed visual inspection and logging of the trench walls, including the compilation of graphic trench logs at a scale of one inch equals five feet.

f) Coordination of trench backfilling and fill compaction, including density testing of the trench backfill.

g) Laboratory testing of representative samples of the trench materials.

h) Analysis of the field data.

i) Preparation of this report, including our findings, conclusions and recommendations, and the results of our trench backfill compaction testing.

FIELD WORK/LABORATORY TESTING

FIELD INVESTIGATION

4.1 Surface Investigation

A geological surveillance of the property was conducted prior to our subsurface exploration. The geologic features which were delineated during this investigation are shown on the Geologic Map, Figure 4.

4.2 Geophysical Survey

A suite of geophysical methods were utilized by Ryland­Cummings, Inc. to investigate the project site. Seismic and magnetic surveys were conducted on April 15, 1981, followed by a gravimetric survey on April 19, 1981,

Ill

Turner "--Realty Project R2411 July 6, 1981 Page Three

The location of each traverse is shown on the Geologic Map. Appendix B of this report contains the Geophysical Investigations report compiled by Ryland-Cummings, Inc., including their findings and conclusions.

4.3 Subsurface Investigation

a) Trenching on .the site was conducted as follows:

i) 777 feet of trench (T-li Geologic Map, Figure 4) was excavated utilizing a tractor-mounted back­hoe during March 23-25, 1981. The average trench depth was approximately 10 feet.

ii) 150 feet of trench (T-2, Geologic Map, Figure 4), with an average 10-foot depth, was dug on March 30, 1981.

iii) On May 13, 1981, two additional short trenches (T-3 and T-4) were excavated in the general

.proximity of the two previous trenches, to depths averaging 15 feet.

b) The subsurface exploration data are presented in Appendix c.

5. LABORATORY TESTING

Representative samples of the trench backfill were tested in our laboratory. The procedures outlined in A.S.T.M. Test Method Dl557 were used to determine the compaction character­istics of the fill materials. The results of this test are presented in Appendix D.

6. TRENCH BACKFILL COMPACTION AND TESTING

Trench backfill and compaction operations were conducted on March 31, and May 14 and 15, 1981. Compaction was obtained by utilizing a small dozer and sheepsfoot and a hydro-stomper. The results of the field compaction tests are presented in Appendix D.

Turner Realty Project R2411 July 6, 1981 Page Four

7. SURFACE CONDITIONS

FINDINGS

The project site consists of approximately 21 acres of gently sloping to flat-lying land, situated along the northeast side of Palomar Street, between Gruwell Street and the cemetery on the northwest, and Central Street on the southeast. The dimensions and general configuration of the property are shown on the Geologic Map, Figure 4.

The site slopes toward the southeast, and drainage is in the form of sheetwash in this general direction. Above sea-level elevations range from 1262 feet at the south corner of the site, to about 1294 feet near the north corner. Vegetation consists almost entirely of native grasses. No surface water was found. The only man-made features observed were a drainage furrow near the northeast end of the property, and a wire fence at the northeast boundary. Underground utilities, such as telephone cables and a high-pressure gas line, are situated along the south­west property boundary.

8. GEOLOGY

8.1 Geologic Setting

The site is located _within the central portion of the Elsinore Trough, which is situated at the southwest corner of the Perris Peneplain in the Peninsular Ranges Geomorphic Province. The valley is bounded on the southwest by the Santa Ana Mountains, whose northeast­facing slopes are comprised of granitic, volcanic and metamorphic rocks. The northeasterly side is bounded by low-lying hills consisting of granitic, metamorphic and some sedimentary rocks of the Perris Peneplain. Early to middle Pleistocene age sedimentary rocks of non-marine origin have formed along the perimeter of the Elsinore Valley, with some deposits extending into the central portion of the valley, especially where the valley becomes narrow. Younger deposits of alluvium are situated in the valley proper and within the adjacent stream channels.

Turner Realty Project R2411 July 6, 1981 Page Five

Locally, nhe project site is underlain by sedimentary bedrock of the Pleistocene age Pauba Formation and an unnamed SANDSTONE unit. The bedrock is capped, in part, by residual and alluvial soils.

8.2 Structural Geology

The Elsinore valley lies within the Elsinore fault zone, a northwest trenching fault zone that extends for more than 200 km from Corona on the north to the international boundary with Mexico. The valley is bounded on the southwest and northeast by the Willard fault and the Wildomar fault, respectively, lying within a down-dropped structural block between these faults, and forming the Elsinore structural trough. Faulted Quaternary age sediments and a youthful topo­graphic expression suggest a moderately young age for these faults. The Wildomar fault lies beneath the site, trending subparallel to Palomar Street. The location of the Wildomar fault is shown in Figure 4. Based on our research and observation of fault-related features along the northeast side of Palomar Street, the Wildomar faµlt is a right-lateral strike-slip fault with a normal

~ component of movement which has resulted in the south­westerly block moving downward relative to the north­easterly block. This condition is illustrated, generally, in the Geologic Cross Section, Figure 5.

8.3 Soil and Bedrock Units

The geologic characteristics of the site are presented at a scale of 1 .. inch "' 200 feet on the Geologic Map, Figure 4, and in the Geologic Cross.section, Figure 5. The geology shown is based on photographic evaluation, research, geophysical surveillance, and surface and subsurface exploration.

The proposed development is underlain by early- to middle-Pleistocene aged, non-marine sedimentary bedrock of the Pauba Formation, which lies in fault contact with an unnamed, early Pleistocene SANDSTONE bedrock. These relationships are shown in Figures 4 and 5. The unnamed SANDSTONE bedrock encountered during trenching consisted generally of fine- to coarse-grained, yellowish- to reddish-brown, poorly indurated (soft), poorly bedded, Silty and Clayey SANDSTONE containing some thin to medium, discontinuous beds of Gravelly SAND and SANO. Some carbonate-filled fractures were found.

Turner Realty Project R24ll July 6, 1981 Page Six

The Pauba Formation bedrock was not encountered during our surface and subsurface exploration. However, exposures northwest of the site consist of fine- to coarse-grained, Clayey and Silty SANDSTONE.

The bedrock is overlain by residual soils consisting of yellowish-brown to brown, damp to moist, firm to stiff Clayey and Sandy SILT, The residual soil grades into the underlying bedrock and -the overlying topsoil, so that a definite boundary is not apparent. The residual soil tends to pinch out toward the northwest as the overlying alluvial deposits thicken.

Alluvial deposits at the site overlie residual soils and bedrock to variable depths. These deposits were found to consist predominantly of fine- to coarse­grained, brown to greyish-brown, damp to moist, loose to medium dense Silty SAND. Some finer-grained deposits of Sandy SILT and Sandy CLAY to Clayey SAND were en­countered towards the east end of trench T-1. The alluvial deposits contain thin to medium beds of fine­to coarse-grained, loose to medium dense Gravelly SAND and SAND, These beds displayed some cross-bedding and heavy-mineral laminations. Fine gravel was usually found along scour surf aces at the bottom of the sand beds.

A poorly developed zone of topsoil covers most of the site. These materials consist of greyish-brown, Sandy SILT and Silty SAND.

8,4 Ground Water

No ground water was encountered during our subsurface exploration (maximum depth 15.5 feet). Research of ground.water publications indicates that the ground water table in the general area is at a depth of about 75 feet, on the southwest side of the Wildomar fault. Seismic refraction data obtained during our geophysical survey indicates that the ground water table may be at 70 feet, where seismic velocities increase. Perched ground water may be present at shallower depths,

. especially following periods of heavy rainfall.

.::

Turner Realty Project R2411 July 6, 1981 Page Seven

9. SEISMICITY

Seismic risk in Southern California is a well recognized factor, and is directly related to geologic fault activity. Seismic damage potential is greater in some areas than in others, depending on the proximity to active or potentially active fault zones, and on the type of geologic structure. In relative terms, seismic damage is generally less intense in consolidated formations, i.e., bedrock, than in uncon­solidated materials, such as alluvium.

In Southern California, most of the seismic damage to man­made structures results from ground shaking, and to a lesser degree from liquefaction and ground rupture caused by earth­quakes along active fault zones. In general, the greater the magnitude"of the earthquake the greater the potential damage.

Seismic hazards at this site are attributed to ground shaking as a result of an earthquake epicentered on a nearby active fault. The Wildomar fault traverses the project site near Palomar Road, In addition, the project site lies at the following distances from the major active faults in Southern California:

Faults

San Andreas San Jacinto Newport-Inglewood

Distances - Site to Fault

35 Miles 20 Miles 38 Miles

NE NE SW

Epicenters of earthquakes exceeding 6 on the Richter Scale of Magnitude within a 70-mile radius of the project site included:

Approximate Distance Date Magnitude Epicenter to Site Fault

5/15/1910 6.0 8 Miles Elsinore 4/21/1918 6.8 22 Miles San Jacinto 7/23/1923 6.3 19 Miles San Jacinto 3/11/1933 6.3 46 Miles Newport-Inglewood. 3/25/1937 6.0 40 Miles San Jacinto 12/4/1948 6.5 56 Miles San Andreas 3/19/1954 6.2 67 Miles San Jacinto

f,.,--- SAN ."'-. UJIS

0B1SPO

1916

MAJOR EARTHQUAKES AND RECENTLY ACTIVE FAULTS IN THE SOUTHERN CALIFORNIA REGION

·.

ACTIVE FAULTS

Tolol Ieng th of foul t zone tho t breaks Ho I oc en e deposits or tho\ hos hod se 1 sm1 c oc hv 11 y

F o ul1 se g men I w11 h surface rupture during on h<S 1 ori c eorthquoke, or with ose1smic fault creep.

Cl Holocene volcanic activity ! Amboy, Pisgah, Cerro Prieto end So lion Bultes )

EXPLANATION. EARTHQUAKE LOCATlONS

1899~ M7+

I

\J M7.7 195Zo

Appro~imote ep1cenlral oreo of earthquakes 1ho1 occurred 1769-19 3 3. M oqmtudes llOl recorded by msl ru men!s prior 1o 190 6 were es \Imo 1 ed from do mo g e reports assigned on Int ens 1 !y VII ( Modihed Mercoh soolel or qreoter; this is l"OIJghly equ ivo le n1 to R ich!e r M 6. 0. 31 modero t e­ear1 hquo kes, 7 majo! or>d one greal earl hquo!o.e ( 185 7) were re por led in the 16 4 -yeor period 1769-1933.

Earthquake epicent~ si nee !9 33, plotied from iTiproved nsl rumen tr.. 29 modemle*., ond 1 h rtt mojor eorthqockes were recorded in the 40-yeoc period 193 3-1973.

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G. A: NICOLL A ASSOCIATES

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Estes A·-Dote July. 19 81

.f>roJ.ect .. .NoR.2411

Turner Realty Project R2411 July 6, 1981 Page Eight

-·----· ----- -··--·-· -···-···

10.

Figure 2 shows the geographical relationships between the ------------site location, nearby faults, and the epicenters of signi­ficant seismic occurrences. During historic times a number of major earthquakes have occurred along the San Andreas and the San Jacinto fault zones in Southern California. From the seismic history of these zones and their close proximity, they have the greatest potential for causing future earthquake damage at this site. During the next 100 years, there is a distinct possibility that an earth-quake of magnitude 8.0 may occur along a local segment of the San Andreas fault and 7.0 magnitude earthquake along a segment of the San Jacinto fault. Based on the proximity of the site to these faults and the nature of the underlying materials, peak ground accelerations of 0.20g and .22g, respectively, may occur during such events. A maximum probable earthquake magnitude of 6.0 is feasible within the Elsinore fault zone. If such an event occurs along the Wildomar fault, peak ground accelerations of .58g may occur.

FAULT HAZARD INVESTIGATION

10.l General

The Alquist-Priolo Special Studies Zones Act of December, 1972,. authorized the State Geologist to delineate "Special Studies Zones" along recently and potentially active traces of the major-fault systems in California. For purposes of the Act, the State Mining and Geology Board regards faults that have had surface displacement within the last 11, 000 years as active,,- and hence as constituting a potential hazard.

In 1979 a number of new Special Studies Zones maps were issued for preliminary review purposes: On January 1, 1980, the preliminary maps were superseded by Official Maps. A portion of the new maps include areas situated along the trend of the Elsinore fault zone. The maps delineate fault hazard zones along various segments of this zone where suspected potentially active faults may be present. The proposed development lies within a Special Studies zone which contains the Wildomar fault;· Figure- 3 shows these relationships. Based on the nature of the development and its presence within the zone, a detailed fault investigation was required by the County of Riverside Planning Department prior to tentative tract approval.

I J

• LOCATION MAP· FOR SPECIAL STUDIES ZOM

2000 0 2000 4000 - --- -a&se Map: .St.ate -of California Special StudielO Zonel'll 19801 .Wildama.r .Quadr.&J;lgle 7.5 minute 10eries

G. A. NICOLL A ASSOCIATES, INC. lilTM IOPICI CONIUI. f ANTI

Estes II

Dote: July, 1981

.Ffoject No: Fi~e Ho' R24ll 3

Turner Realty . Project R2411 July 6, 1981 Page Nine

10.2 Research and Photographic Evaluation

A number of published and unpublished geologic reports and maps, and stereoscopic aerial photographs were examined during this investigation. The geologic maps indicate that the main trace of the Wildomar fault crosses the site as shown in Figure 4. The presence of the fault was further substantiated during an evaluation of stereoscopic pairs of aerial photographs. The fault is evidenced as a vague lineation caused by a subtle gradient change along the approximate trend of the mapped fault. No changes in vegetation characteristics were observed during the photographic evaluation. One geologic publication (Kennedy, 1977) shows another major fault segment about 200 feet north­east of the northeast property line, with a trend parallel to the suspected main fault break on the site. This report indicates that both fault segments experienced fault movement during the late Pleistocene time, but no information ~as available to indicate Holocene movement •.(within the past 11, 000 years).

The results of a seismic hazards study conducted by the California Division of Mines and Geology between 1973 and 1977 (Weber, 1977), indicates that late Quaternary (500,000 years) to Holocene movement has occurred along the trend of the Wildomar fault northwest of the project site; specifically, in the zone northeast of Palomar Street, from the site to about 3,000 feet west of the intersection of Palomar Street and Corydon Road.

" T,',~• • •• ~---·--·

With one exception, historic seismic events along the Elsinore fault zone are limited to microseismic earthquakes. The 6.0 magnitude earthquake that occurred in the Lake Elsinore area on May 15, 1910, is the only major event recorded in historic times. This indicates the relatively inactive nature of the Elsinore fault zone with respect to macroseismic earthquakes.

•

Turner Realty Project R2411 July 6, 1981 Page Ten

10.3 Preliminary Fault Trenching

Preliminary trenching was conducted at the site on March 23-25, and 30, 1981. Approximately 930 feet of trench, T-1 and T-2, was excavated during this phase of our field investigation. Trench depths varied from 8 to 11 feet. Graphic representation of the trench sidewalls for T-1 and T-2 are pre­sented in Figures 7 through 14 Of Appendix c.

On the basis of our research of the geologic literature and prior to the onset of our field investigation, it was anticipated that Pleistocene-age bedrock would be encountered during trenching. However, our prelim­inary trenching revealed that the majority of the site was covered by alluvial deposits, with the deposits thickening towards the northwest. An examination of the various materials encountered and the features observed indicated that no active fault breaks were present in the upper 11 feet of subsurface material, in the area trenched. As a result of our preliminary findings, a geophysical survey was conducted to locate the Wildomar fault beneath the alluvial cover .

. . - - . ··-··-,·····---,;-_---,---,----:---o--10. 4 Geophysicar Survey

The details and results of the geophysical survey conducted at the project site are presented in Appendix B of this report.

A number of geophysical· methods· were employed-during this investigation. Two traverse lines were established near the previous trenches. These lines were designated L-1 and L-2 as shown on Figure 4 and in Appendix B. The same stationing criteria was utilized that was established during the preliminary fault trenching. Seismic, magnetic and gravity traverses were conducted along these lines for the purpose of locating and defining the nature of the Wildomar fault.

The geophysical data indicated that major anomalies are located in close proximity to the mapped trace of the Wildomar fault. The results of the geophysical investigation allowed us to conduct a more detailed trench investigation across the fault.

•

Turner Realty Project R2411 July 6, 1981 Page Eleven

10.5 Final Fault Trench Examination

Following the evaluation of geophysical and previous trenching data, two deep trenches, T-3 and T-4, were

-excavated at the locations shown in Figure 4. The "trenches were excavated and examined to detennine if any active fault breaks were present in the upper 15 feet of the alluvium. Detailed graphic represent­ations of the northwest trench walls are presented in Appendix C, Figures 15 and 16.

In trench T-3 a sandy channel deposit was traced across the length of the trench. A moderately well defined erosion surface, observed at the bottom of the deposit, was traceable over most of the trench, becoming less distinct near the northeast end.' The only variation in the continuity of the channel deposit and the erosion surface was observed at Station 2+89. Here, a bed of cross-bedded sand and a thin silt layer tenninates against what appears to be a fracture or an erosional surface. Examination of the materials above and below this feature revealed no offset in these soils.

A thorough examination of trench T-4 was precluded because of the intense caving experienced during excavation. Only the upper 10 to 11 feet of the northwest sidewall could be logged. No evidence for active fault breaks was found in trench T-4.

CONCLUSIONS AND RECOMMENDATIONS

11. CONCLUSIONS

Following an analysis of the data accumulated during the course / of this investigation, we conclude that the Wildomar fault crosses the project site as shown on the Geologic Map, Figure 4.

•

Turner Realty Project R2411 July 6, 1981 Page Twelve

The Wildomar fault appears to have displaced Pleistocene-age bedrock near the northwest end of the property. How­ever, detailed examinations of fault trenches excavated within the bedrock and alluvium underlying the site, revealed no active fault breaks in the materials encountered. Although our findings indicate the absence of an active fault break on the segment of the Wildomar fault that crosses the site, it cannot be construed that the entire Wildomar fault is not active, just that no evidence of Holocene movement was encountered at the site. Therefore, at the site, the Wildomar fault is considered to be potentially active.

An evaluation of historic seismic events along the Elsinore fault zone, indicates that the zone appears to be relatively inactive with respect to microseismic earthquakes. With this in mind and considering the length and complexity of the Elsinore fault zone, we conclude that the potential for a major earthquake occurring along the Wildomar fault at this particular site is low.

12. RECOMMENDATIONS

Based on our findings and conclusions we feel that ground rupture along the segment of the Wildomar fault underlying the site is highly improbable, Therefore, no special building setback zone will be required,

Although the potential for a major earthquake occurring at the site is low, a magnitude 6.0 earthquake in the Lake Elsinore area is possible. Considering·the nature of the proposed structures, proper consideration of the primary seismic risk of strong earthquake-induced ground motion should be made during the design of all the structures, Based on the geo­physical data obtained for the site, we have calculated a site period, T~, ranging between 0.19 and 0.26 seconds, As a result, the lower limiting value for T8 of 0.5 seconds should be used when calculating the site-structure resonance coeficient, s, for use in the Uniform Building Code seismic force equation.

•

Turner Realty Project R2411 July 6, 1981 Page Thirteen

13. LIMIATIONS

This report presents recommendations pertaining to the subject site based on the assumption that the subsurface conditions do not deviate appreciably from those disclosed by our exploratory excavations. However, in view of the general geology of the area, the possibility of different local soil conditions cannot be discounted.

Professional judgments represented in this report are based .partly on evaluations of the technical information gathered, partly on our understanding of the proposed construction, and partly on our general experience in the geotechnical field. We do not guarantee the performance of the project in any respect, only that our engineering work and judgments rendered meet the standard of care of our profession at this time.

We appreciate this opportunity to be of service to you. If we may be of further assistance to you on this or other projects in the future, please do not hesitate to call.

Very truly yours,

G. A. NICOLL AND ASSOCIATES, INC.

John F. Dablow, III Chief Geologist­CEG 1032

~~.b:i..« ·Grayso. R. Walker Vice President RCE 29807

JFD/GDH:bjd

Enclosures: Location Map, Figure l Seismicity Map, Figure 2 Location Map for Special Studies Zone, Figure 3 Geologic Map, Figure 4 Geologic Cross Section, Figure 5 References, Appendix A Geophysical Survey, Appendix B Fault Trench Investigation, Appendix c Unified Soil Classification System, Figure 6 Trench Cross Sections, Figures 7 - 16 (Appendix Cl Laboratory and Trench Compaction Testing, Appendix D Sununary of Field Density Tests, Table I

>-

~ l.~

l_ I 01s I

l- ~

_, ... ----

400

feet

K£Y

Alluvium

.Pouba Famation -- bedrock

lk1nomed SANDSTONE Unit

Geologic Contact

~ ~--···· Fouh- showing relative ,-o movement; tblted where

[ r-4 Test pit

[ -I

L-2 I Geoplrysical line

--

L A A' ... 4 Geobgic Cross Sec/ion ~

L

•••••••••• _Qo/_

L-

A

Ba~ Mop, Ri~side Cowty Flood Como!

Mop. S«:licn "' T.6S, R4W

Oaf

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STR£Er

•••• ••••••••

C>. A. NICOLL A ASSOCIATES

("UH Klll'IC( CONSULT ANTS

G£0LOGIC- MAP

-

' i• •••• I' •••••• it •••••

/

Estes A Date J.Jly, 1981

R2411 4

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.

-

•.

I

GEOLOGIC. CROSS SECTION

N40E

Ii f'Oomgr Street NE end of f(lllt •

A lnlrdl ~Q •. ?1' 77) A'

-NW end of fol.ii Project B<iundi:J'yl 1300. i lrench C:> to. o + 16) -ooo T-3

j Qol ?-==-?-==--r=-fr- 1\lllre<l"' ;:~:- d~lit, .~ 1200 - .,_ 1200 -§! Qpl "' Q 1100 -

zoo 0 200

~ • wertlcotl I

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400 I

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G. A. NICOLL A ASSOCIATES, INC. lARTll KllNCl CONSULT MT•

Qui

'"" 1100

See KEY, Figure 4 for aplanotion of symbols.

Estes A

Dot•• July, 1981 Fi9W• No: 5

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Project R2411

APPENDIX A

References

Albee, Arden L., 1967, Earthquake characteristics and fault activity in Southern California: Bull. A.E.G.; P. 9~33.

California Department of Water Reeources, 1975, Hydrologic data: 1975, Volume V: Southern California: Bulletin Number 130-75, 487 p.

California Department of Water Resources, 1973, Hydrologic data: 1973; Volume V: Southern California: Bulletin Number 130-73, 483 p.

California Department of Water Resources, 1971, Hydrologic data: 1971, Volume V: Southern California: Bulletin Number 130-71, 503 p.

California Department of Water Resources, 1964, Crustal Strain and Fault Movement Investigation: Bulletin Number 116-2, 96 p.

" Engel, Rene', 1959, Geology of the Lake Elsinore quadrangle, California: California Division of Mines and Geology: Bulletin 146, 154 p.

Greensfelder, Roger W,, 1974, Maximum credible rock acceleration from earthquakes in California: California Division of Mines and Geology, M.S. 23, (explanation 12 pages).

Hart, Earl w., 1977, Fault hazard zones in California: California Division of Mines and Geology Special Publication 42, 1977 revision, 24 p.

Jenning, C. w., 1973, Preliminary fault and geologic map;:California Division of Mines and Geology, Preliminary Report 13, Scale 1:750,000, 2 sheets. ~

Kennedy, Michael P., 1977, Recency and character of faulting along the Elsinore fault zone in Southe.rn California, Riverside County, California: California Division of Mines and Geology Special Report 131, 12 p.

Langenkamp, David and Combs, Jim, 1974, Microearthquake study of the Elsinore fault zone, Southern California: Bulletin of. the Seismological Society of America, Volume 64, Number 1, pp. 187-203 •

I. l. I l

• Appendix A l>roject R2411 Page Two

Leeds, David J., 1973, The design earthquake, in A.E.G. Special Publication, October, 1973, Geology, Seismicity, and Environmental Impact, pp. 337-347.

Mann, John F., Jr., 1955, Geology of a portion of the Elsinore fault zone, California: California Division of Mines and Geology Special Report 43, 22 p.

Nicoll, G. A. Nicoll and Associates, Inc., 1980, Soil, geologic and liquefaction study, proposed Pacific Southwest Financial Center, Rancho California, California: Project Development Report for Kecor Financial Group, Brea, California: 12 p.

Rogers, T. H., 1965, Geologic Map of California, Santa Ana Sheet California Division of Mines and Geology, scale 1:250,000.

Seed, H. Bolton, 1970, A simplified procedure for evaluating soil liquefaction potential: Earthquake Engineering Research Center, University at Berkeley, Report No. EERC 70-9, 23 p.

Toppozada, Tousson R., 1978, Seismicity of California 1900-1931, California Division of Mines and Geology, S.E. 135, 39 p.

Townley, Sidney D., 1939, Descriptive catalog of earthquakes of the Pacific Coast of the United States, 1769 'to 1928: Bulletin of the Seismological Society of America, Volume 29, Number l, 297 p.

Weber, Harold F., Jr., 1977, Seismic hazards related to the geologic factors, Elsinore and Chino fault zones, northwestern Riverside County, California: California Division of Mines and Geology Open File Report 77-4 LA, 96 p.

wood, Harry o., 1916, California earthquakes: Bulletin of the Seismological Society of America, Volume 6, Numbers 2 and 3, 194 p. .

AERIAL PHOTOGRAPHS

Riverside County Flood Control Department, 1980 Flight, Exposures 89-94: scale: 1 inch ~ 500 feet.

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

•

APPENDIX B

Geophysical Survey

Project R24ll

This appendix contains the Geophysical Investigations report

compiled by Ryland-Cummings, Inc., Pasadena, California. The

figure number~ referred to in their report, Appendix A, apply

only to those included in this appendix. Figure l of the Ryland­

Cummings ~eport corresponds to Figure 4 of our report.

•

,_

GEOPHYSICAL INVESTIGATIONS Palamar and Central Streets

Wildomar, California -

RYLAND-Ct.MMINGS, INC.

Project Number 81-18-03

April 27, 1981

Prepared for Nicoll & Associates, Inc.

RYLAND-CUMMINGS. INC.

•

•

INTRODUCTION

A suite of-geophysical methods were utilized to investigate

the site located north of the intersection of Pala.111ar and

Central Streets in Wildomar, California. The purpose of

this investigation was to locate and define the nature of

the Wildomar Fault. This fault is currently mapped as

crossing the site on an Alquist-Priolo Special Studies Zone

Map. Field work was conducted on April 15 and 19, 1981.

Several anomalies were identified on the magnetic,

gravity, and seismic surveys. Coincidence of several of

these anomalies indicates a probable location for the

fault. The location of these geophysical lines is shown

on Figure 1.

METHODOLOGY

Seismic Refraction

Seismic refraction exploration makes use of the waves

generated by an energy impulse to determine material

properties and subsurface configuration. The impulse is

initiated at a known point and received at.various distances

from that point by ground motion sensitive transducers

(geophones). By knowing the distance from impulse to the

9eophones and the time to travel those distances subsurface

data may be extracted.

RYLAND-CUMMINGS, INC.

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D.t. J.O \I~

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For this survey we used a Geometrics ES-1210F 12

channel seismograph. Geophones were placed at 10 foot

intervals for a total profile length of 250 feet. Energy

illlpulses were in the fo:cm of sledge hammer impactsi these

were shot at each end of the profile, at the center, and at

offset distances from the end of the profiles. The survey

was primarily designed to augment the trending porgrams and

target depths of 20-30 feet were requested. offset shots

allowed for penetration to on the order of 100 feet.

The 24 geophones (12 at a time) are connected to the

seismograph which amplifies each signal separately and

displays the data both on a CR1 screen and as a paper record.

The seismograph also supplies timing lines which allow

for time calculation to 1 millisecond.

The data is plotted in a time-distance plot which

shows time of energy arrival versus distance. From this

graph the acoustic '7elocity and configuration of subsurface

layers may be determined. Data derived from shots offset

from the' ends of the line may be used to map the configuration

.of various refraction horizons.

This survey consisted of two seismic refraction lines

for a total survey length of 960 feet.

Gravity

The gravity method measures minute changes in the vertical

component of the earth's gravitational field. These small

' changes reflect variations in the density distribution

RYLAND-CUMMINGS, INC.

81-18-03 • -3-

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of the subsurface. Such changes may be correlated with

geologic structure.

We employed a LaCoste-Romberg Model G gravimeter for

this survey. This instrument reads to about one part in

a billion (1 microgal) of the earth•s field and is accurate

to about 10 parts in a billion (10 microgals).

A number of corrections must be applied to gravity

data before its interpretation. The first of these is

drift. This is due to earth tides caused by the sun and

moon and also due to small changes in the gravimeter

itself. These are corrected by returning to a base station

at time intervals during the survey.

Another correction, the free~air, is due to variations

in elevation, distance from the center of the earth. This

amounts to about +0.094 mgal/ft. Since this correction is

so sensitive to elevation we surveyed both lines using

a hand level and rod. It is expected that elevations should

be good to less than +0.25 ft. The Bouguer correction

is also dependent on elevation. This corrects for the

gravitational effect of a slab of rock material underlying

the survey elevation. We aSsUllled a rather high density

of 2.68 9111/cm3 for this slab to accentuate the effect

of low density materials beneath the profiles. This

amounts to a Bouguer correction of -0.034 mgal/ft. The

free-air and Bouguer corrections together come to +0.060

mgal/ft •

RYLAND-CUMMINGS, INC.

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oi io-v.l -4-

Another correction is made for change in latitude

along the survey line. The correction increases to the north

and is relatively small when compared to the elevation-

related corrections.

These data were not corrected for the·topographic

effects of the surrounding mountains (terrain correction).

It was felt that since the profiles were distant from

the mountain front the correction would not greatly influence

the variations in gravity. Thus the data presented is

simple Bouguer gravity on an arbitrary local datum ( each

line on a separate datum). Gravity stations were at 20 foot

intervals along lines 1 and 2; a total of 50 stations

were occupied •

Magnetics

The magnetic method measures variations in magnetic

1 · mineral content (i.e. magnetite) in the subsurface by

measuring the earth's magnetic field. The juxtaposition

of two rock types of differing contents will produce an

anomaly.

We used a Geometrics Model G-816 total field proton

precession magne~ometer. This measures the changes in

the magnetic field to about l part in 50,000. The only

correction made was to return to a base station to account

for di urn al variations in the earth's magentic field.

The magnetic method is greatly affected by cultural features,

, particularly power lines and iron and steel pipes.

,.

RYLAND-CUMMINGS, INC.

81-18-03 ' -5-

•

The magnetic survey had station intervals of 10 feet

on lines l and 2. A total of 98 statio~s were occupied.

OBSERVATIONS

Seismic Refraction

The seismic refraction method was used to define the

subsurface horizons and locate any anomalies which could

indicate a fault.

The seismic refraction survey generally located four

subsurface layers:

·General Velocity

lOOO ft/sec

1350-1700

2500-3300

4200-6000+

Possible Composition

Loose alluvium

Old alluvium

Sandstones-Pauba and Unnamed Pleistocene Fm

Water Table or more indurated bedrock.

These layers are identified throughout Lines l and 2

but not all are present in all locations.

Line l (Figure 2) shows the first layer with a thickness

of about 15 feet on the southwest end and 10 feet to the northeast.

The second layer is about 15 feet thick to the southwest

but pinches out near station 350; it is not continuous

further east. The deepest layer is located at a depth of

about 70 feet.

Discon~inuities in the lower refractor are indicated

RYLAND·CUMMINGS, INC.

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at stations 190-200 and at 270-280. These are not "classical"

fault offsets but clearly show some discontinuity.

Line 2 (Figure 3) is located to the northwest of Line

l. It is in many ways similar to Line l. The second layer

thins to the east and is not always present in the far

eastern segment. A minor discontinuity is shown at stations

40-50; major discontinuities are observed at 300-320 and

400-410.

Gravity

The gravity survey shows distribution of mass in the S'

subsurface. Figure ,K shows the data for the gravity surveys

in both lines. The gravity data are on arbitrary datum

so that the level of the points is not important. Much of

the curvature of the lines is a figment of the data reduction

method and also is not important.

Line l shows a strong anomaly at about station 280

with a higher density to the northeast. This could be produced

by juxtaposition of rock materials of differing densi~ies

or location of higher density material nearer the surface;

amplitude of this anomaly is on the order of 0.1 mgal.

A smaller anomaly may be located near sta~ion 450.

Line 2 is similar to Line l. A positive anomaly is

located at station 310 with an amplitude of about 0.05 mgal.

Another anomaly is located near station 450.

RYLAND-CUMMINGS, INC.

-7-

Magnetics

The magentic method measures changes in subsurface

content of magnetic minerals. Line 1 shows a distinct

anomaly with a magnetic low east of station 270 with an

amplitude of 25 gammas. A possible anomaly, or perhaps only

a part of an anomaly associated with the pipes and powerlines,

is located near station 120.

Line 2 is similar to Line l particularly the large low

near station 330 with an amplitude Of 65 gammas.

CONCLUSIONS

c A ccwbined program of seismic refraction, magnetics, and

' gravity surveys. was used to determine the subsurface configuration

of the site, particularly the location of discontinuities.

The anomalies located in these investigations are due

tq the juxtaposition of materials of differing properties.

These properties may be due to many features. In the seismic

:refraction method anomalies would be ·developed along buried

channels, boulder trains, faults, erosional, and other

features. The solutions to the gravity and magnetic anomalies

are ambiguous and may be due to a number of sources

including faults. Thus the presentation of the location of

these anomalies does not necessarily indicate the location

of faults but rather some occurence in the subsurface.

additional studies such as trenching and borings may be

:required to ascertain the exact nature of the anomaly.

RYLANO·CUMMINGS, INC.

:

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The following table shows the location of the various

anomalies;

Seismic

Magnetic

Gravity

LINE l

190-200 270-280

120 (?) 270

280 450

LINE 2

40 - 50 · (minor) 300-320 400-410

330

310 450

From this data it is clear that a major anomaly is located

on each line and is supported by data from all three sources;

these locations are 270-280 on Line l and 300-330 on Line 2.

Due to the strong indication at these locations and to the

rather close correspondence bet~een these locations and the

mapped trace of the fault, it is quite likely that this

is its location.

RYLAND·CUMMINGS, INC.

FIGURE 1. LOCATION OF GEOPHYSICAL LINES

-QI !II u. I ~ -c. QI c

"

2000

10uv

1500

' 1,/ 7000

I 5500

" .. 1100 --:i200

,..- 2000 1100 ,, 2500 ,, 2220 /

- -- - -

100 L-~~~~~~~~_J.'~~~~~~~~~-1-.1 ~~~~~~~~--l.1~~~~~~~~~-'--1 ~~~~~~-'

0

-

100 0

SW

1000

1100

3500

I

LINE 1

1000 Jvuu

1650 1800 -3200 2500

z- -! - --~ -

( t

LINE 2

FIGURES 2-3. INTERPRETIVE SEISMIC PROFILES

1670 -oo--v

3300 3000

6000

I

400

"

49350

"' "' E E

"' t::I

"

;t,

,.

" (

FIGURE 4.

MAGNETIC SURVEY

Line 1

I .

I I I '

Project R24ll

APPENDIX C

Fault Trench Investigation

Fault trenching at the project site was accomplished using a

tractor-mounted backhoe with a 24- and 36-inch bucket. A

total of four trenches were excavated to depths ranging from

B to 15 feet. Zero (0+00) reference points for trench stationing

were established 10 feet northeast of the pavement edge of

Palomar Street. Hydraulic shoring was utilized as a safety

precaution to increase the stability of trench side walls.

Intense caving experienced in trench T-4 precluded a detailed

inspection of the 12 - 15 feet (0+00) depth of the alluvium

in this excavation.

The bedrock and soils encountered during the trench examinations

were logged by our Engineering Geologists. Graphic logs of the

physical characteristics encountered are shown in Figures 7 through

16. The soils were classified visually and generally, in accordance

wth the·Unified Soil Classification System described in Figure 6.

Following our subsurface exploration, all excavations were backfilled.

' \ \

\

5.0

" •

FIGURE 5. GRAVITY DATA

/----..

/--~Line1 ___,---.,,......

Line 2

Project R2411

APPENDIX C

Fault Trench Investigation

Fault trenching at the project site was accomplished using a

tractor~mounted backhoe with a 24- and 36-inch bucket. A

total of four trenches were excavated to depths ranging from

8 to 15 feet. Zero (0+00) reference points for trench stationing

were established 10 feet northeast of the pavement edge of

Palomar Street. Hydraulic shoring was utilized as a safety

precaution to increase the stability of trench side walls.

Intense caving experienced in trench T-4 precluded a detailed

inspection of the 12 - 15 feet (0+00) depth of the alluvium

in this excavation.

I I _,.~~~-·-=-----------------------------

! I

were logged by our Engineering Geologists. Graphic logs of the

physical characteristics encountered are shown in Figures 7 through

16. The soils were classified visually and generally, in accordance

wth the Unified Soil Classification System described in Figure 6.

Following our subsurface exploration, all excavations were backfilled.

UNIFIED SOIL CLASSIFICATION SYSTEM

MAJOR DIVISIONS GROUP DESCRIPTIONS IYMBOU

,.~. w.11 9rad•d gr-anl•, uravel-Mnd o•., ow

CUAN £61 ml•t......,t llttl• .,- na fines.

Gm:AYILS ,~~tt, C Utt .. ~ •• ftn..) o!:,,v "CllOJ'ly grad-d 9ra .. t1 Or ljllrG,,.1-MIAfl

OP mhi:tu,.., Uttla or no flfMti. ORAVUI •x,. •

(M•r• thmn '°" -t : .... .. _ .. fr•1:tiWI la ,/• :·· LA•N• ihtwi lhilli •' . OM Siity grav•l11 9ruv•a..1oncl-•llt Jnl•turM. N..4 ...... 111lq.J • •• GRAV EU .......

WITH FINll!S . .

. ·- ·. CA11t1tr•cl•lthl .... ....,. • •.t. Cla.,.y 9fav•I•, 9n;11Ql-aund-clay CoA•H ......... ·.· .. - oc ' .. ml•ture1.

ORAINID -~·~.:.: IOILI

~·~?.~~ (Mot••~ Ml"- of IW ¥1•11 graded 1ancls, g1aH1lly Minds; ..._. .. ,._, iA LAAGIR ~:~:~: llttle or no t•ne1. .......... 200.-.. CLEAN SANDS ....... (Llttl• ., - fl••• I .···.-·

.:-:-::. ......... IP Poarly 1.-.dei::I .-nds _ot gwvelly 1Gnda, .... ~ llttl• or na fin•.

$ANDS :,::·.-:: ····· t-. ....... ~ ..

\·~;ff~\ 11; ...... lr•l:t'- I• SM Siity 1and11 M1nd-1llt mh1:tuir•li· f.111A1,LI• ti-n th•

....... •J9."'• •hi ... SANDS .·~:('.~;\

WITH FINIS (AHta01111iil• •HIMl•_.•t •• 11-..t ,.

S( Cla'f*y sund11 Mnklay •l•tur.s .

-- h1otgank 11tt1 Cindi very fin• ...uilt, rmk ~- ML t•a1,.1r, aUty or ,.:IC1P'i' fl,.. MNMlt. or cJG.,.,. -- alha with allght ple1tlclty.

llL Tl AND CLAYS l!ICL 1 ... or9anlc ch1ya of law to tn•dlutn IL~ 11.a1 ._.,. tllen 10, ll'lastlclty1 gt"411ftll)' cloys, ._ndwi <h•Y•1

1llty ctay1, l•on cloy1.

flNI OL o, • ..,.~ ..... ic11ttll a....,.ac .... ., clays of

ORAINID low plaatkhy.

IOILI

~MN lno,gonic: ...... macci1ceou• at dlat•-

(~ffMtllN'l.•f fnlCIC•ou• fin• .antlly or 1llty 10U11 Met., ..... uu.a.a.1• •lo1Uc •lit• • . ~ ... ,. ..... _,

SILTS AND CLAYI

~ (N ltMJr-9anlc cloy• of hl1h plo•tlclty, fL'41-' 1.-t ORIAI•• tt.M Ht tot clay1.

OH Or9anl..- 'ck:lyt ol m•dlum to hl9h plntklty1 or.-nk Ailts.

- -.r.~

. -: ... HIGHLY ORGANIC IOILI

....... Pt Pt.at anti oth•r highly organic t.oll&.

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lfll'"M'T CltlllflCAIIONSt lolls pcir•f•11ln9 characterl1tlc1 of two 9rouip1 ar• ll•tl9nat•d by 1;cu111blnatla1111 of 9raup aymbol1.

PA•llCLI I I Z I LIMITS

SILT or CLAY

,114.,._ illl, ..... lllVI llZI

Estes "A"

0. A. NICOLL & AHOCIAIH, INC. Dat•• July / 1981 Project Not

R2411 6

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o t-::~~-~--~~~·::-:=~~~~~·':=-:-::--=-::-:::::~-::;:-::.::~::-::-~s;:H;:-S:;;:;;;;;-~;--:S:;:;;;-:~-;:""-::-":--=~"'.'=':"":=-::;:":""""'"":-=---:::::--:-:-:~G~..-~:~d~S~u;r:lo..~~~e~-"f~:__-------~-~~J - ..:. ·. ·,-_! . . - . :- . - ~ . . - ._ .. · - .. :, . ·.: . .' ·- · .. , . -,. -• S;/ty SAND ~c S...-y_ Sll1". - .. :: ·- .;. • . . TO :.J ' : - - - --:-~- - - - - - - -· - -;:::. - - - -- _ -=- ~-::._·.:.- ·- ~· ..:...-_---.:_ . .:.:_ _.,:.:_OIL_-.·_-_ _-~----!-:..·_ . _. - ~ • • - - -· _....!.- - _-._::.-._- --·- - - D "'-" ----

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l u G. A. NICOLL & ASSOCIATES Dote July, 1981

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Project R2411

APPENDIX D

Laboratory and Trenching

Compaction Testing

FIELD AND LABORATORY PROCEDURES

Field Testing Procedures

Test Methods - Field density tests were performed with a 6-inch sand cone in accordance with the pro­cedures outlined in A.S.T.M. Test Method Dl556. Hand-driven steel tubes were also used to obtain undisturbed soil samples as specified in A.S.T.M. Test Method D2937.

Number of Tests - The results of the 18 field density are presented in the "Summary of Field Density Tests", Table I •

Location of Field Tests - The approximate location and depth of each field density test is indicated in Table I.

Trench Backfill - Trench backfill consists of native excavated materials. Native materials are typically fine- to coarse-grained Silty SAND.

Backfill Compaction - All trench backfill was compacted to a minimum of 85 percent relative compaction to within 3 feet of the existing ground surface, and 90 percent within the upper 3 feet as required by the Riverside County Planning Department. Compaction equipment consisted of a small dozer with a sheepsfoot and a tractor-mounted drop hammer.

..

Soil ~

A

B

•

I . I .

I

..

Laboratory Testing Procedures

Appendix D Project R24ll Page Two

Test Methods - Soil samples obtained from the field were visually inspected and, when necessary, additional laboratory testing was performed to confirm identification. The procedures outlined in A.S.T.M, Test Method Dl557 were used to determine the compaction characteristics of fill materials. The results of our laboratory ! compaction tests are presented below:

LABORATORY COMPACTION TEST RESULTS

Soil Optimum· Maximum Description Moisture, % Dry Density, p.c.f.

Silty SAND 10.3 129.2

" Silty SAND 11.5 125.0 l'

-~ ,, -Iii.

DATE TEST OF

'10. TEST 1981

1 3/31

2 3/31

3 3/31

4 3/31

5 3/31

6 3/31

7 3/31

8 3/31

' 9 ~/31 -i 10 !f/31 ' ll 5/14

' 12 5/14

' .·13 5/14

114 5115

I 15 5115

16 5115

17 5115

18 5115

..

SUMMARY OF FIELp DENSITY TESTS

EL EVA· REFER-TION ENCE LOCATION (feet) CURVE

.

T-1, NE end -7 B

T-1, Center -8 A

T-1, sw end -7 A

T-1, center -5 A

T-1, sw end -2 A

T'-1, NE end -4 B

T-1. center -2 A

'"-2. Center -8 A

TI-2. NE end -5 A

"'-2 . SW end -2 A

lr-3' sw end -ll B

T-3, Center -9 A

m_3 . NE end -6 A

m_3 Center -3 B

""-4 Center -1.5 A

TI-4 - Center -8 A

,.,_4 _ Center -5 A

n_4_ <'enter _,.' h

.

G. A. NICOLL & ASSOC IA TES, INC. .EARTH SCIENCE CONSUl.TANTS

MAXIMUM DRY

DENSITY (pcf)

125.0

129.2

129.2

129.2

129.2

125.o

129.2

129 .2

129.2

129.2

125.0

129.2

129.2

125.0

125 n

125.0

1'50

1 '' n

FIELD

~~ WATER DRY '~-.;; MARKS CONTENT DENSITY f<_,'v'?-~ (%)

8.9

9.8

10.1

10.5

9.8

9.5

10.2

9.2

10.0

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10.4

8.9

9.9

8 6

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9.2

11 "

R n

(pcf) ~ c

110.0 88 Pass

ll6.3 90 Pass

117.4 91 Pass

118. 7 92 Pass

118.1 91 Pass

113. 5 91 Pass

120.1 93 Pass

112. 5 87 Pass

117. ~ 91 '>•~s

,, 8.6 n~ -~-

106.7 85 Pass

112.6 87 Pass

114.6 89 Pass

,, l ? nn n ___

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114. 7 RQ Pass

l 2? 7 no n--c

117_<; '" ,, ___

Estes •1A 11

Dole' July, 1981

Project No' R2411

TABLE. I

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