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INTER-OFFICE MEMO DATE January 29, 1986
FROM JOHN BOWMAN~ Certified Engi~eering Geologist
TO BOB HENDERSON Chief Building Inspector
PHONE 3823
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SUBJECT Review And Acceptance Of Geologic Reports For Bernard Irish Property, Morongo Valley, LG 0043
1. I have reviewed the reports entitled• Report of Special Studies Zone Investigation 50707 Laurel Trail, Parcel 584-211-12, Morongo Valley, San Bernardino County, California, dated March 15, 1985; prepared by SCS&T 8531012, Report No. 1.
Report of Special Studies Zone Investigation, 50707 Laurel Trail, Morongo Valley, San Bernardino County, dated May 28, 1985; prepared by Southern California Soil & Testing Inc., SCS&T 8531012, Report No. 2,
Addendum to Report of Special Studies Zone Investigation, 50707 Laurel Trail, Morongo Valley, San Bernardino County, dated July 15, 1985; prepared by Southern California Soil and Testing, Inc., SCS&T 8531012, Report No. 3.
Letter dated September 23, 1985 from Mr. Larry L. Schoelkopf, Building Official to Mr. Bernard Irish advising him that a map delineating the area of the property investigated for surface fault rupture hazard shall be submitted.
And letter report No. 4, subje~t: Proposed Single Family Residence, 50707 Laurel Trail, Mo~ongo · Valley, San Bernardino County, dated October 30, 1985, prepared by Southern Califirnia Soil and Testing, Inc.
And acceptance of the reports as revised and appended is granted this date.
2. It should be pointed out that the area proven-out for suitability for building does not include the proposed single family res-idence location as shown on the map included with the October 30, 1985 report.
3. If the suitability for building area, as so defined by the map referenced abovd, is not acceptable to the builder, additional trenching and geology work will be required.
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. ' STATE OF CA1,1f0f<NIA·-THE ~ESOU•C£S AGENCY f 8b GfOli!:GE OE'UKMEJIAN. GoveMOI'
DEPARTMENJ PF tONSERVATION
DIVISIO~ OF MINES AND GEOLOGY • BAY AREA REGIONAL OFFICE 380 CIVIC ~. SUIT~ l 00 PlfASA.NT Hill CA ~ .. 523-1991'
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Jr. John c. Bowman, Jr. Certified Engineering Geologist Department of Building and safety Land Management Department Environmental Public Works Agency County of San Bernardino 385 N. Arrowhead Avenue San Bernardino, CA 92415
Dear Mr. Bowman:
February 10, 1986
we are placing on open file the following reports, reviewed and approved by the County of san Bernardino in compliance with the Alquist-Priolo special Studies zones Act:
Special Studies zone investigation, 50707 Laurel Trail, Parcel 584-211-12 1
Morongo Valley, San Bernardino County, CAI by Southern California Soil and Testing Inc.; March 15 1 1985, with supplements of May 28 and July 15 1 1985,
Fault investigation, lot split-single family residence, 35467 Ivy Avenue, Yuccipa, CA; by Pioneer Consultants; March 22, 1985.
Please note that only Sheet l of 3 of the trench log was submitted with the report; please submit sheets 2 and 3 to complete our file.
Also, please send all future reports to me in Pleasant Hill where our report file is kept.
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Sincerely yours,
Ead w. Hart senior Geologist &
Program Manager
KENNIITH (:, TOPPING Dcpmy Ad111i11i~tr11tcr Development ~rvicrli
ENVIRONMENTAL PUBLIC WORKS AGENCY
LAND MANAGEMENT DEPARTMENT
JOHN N. JAQU£SS l,11nd ~fa~ment Director
OJ'FICE OF PLANNJN(i Coullty PlanniD.11; Offl~
3SS N. Arrowhead Avenue, San Bernardino, CA 92415 OFFICE! OF SU&V£YOR Claude D. Tomlins011, LS.
January 31, 1986
State Geologist California Division of Mines and Geology P.O. Box 2980 Sacramento, CA 95812
a:iunty S\lrveyar
OFHCE OF BUILDrNG AND SAFETY LllIT)I L Schoelkopf, P.E. County Building Offidal
SUBJECT: Submittal of geologic report for project located within a special studies zone, San Bernardino County, California
1. In compliance with the policies 6f the State Mining and Geology Board, please fine enclosed one copy of geologic report entitled:
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REPORT or SPECIAL STUDIES ZONE INVESTIGATION 50707 LAUREL TRAIL, ?ARCEK 584-211-12, MORONGO V~.LLEY, i3AN BERNARDINO COUNTY, CALIFORNIA.
REPORT 01' SPECIAL STUDIES ZONE INVES'I'IGATION, 50707 T"AURE.L TRAILS, MORONGO Vl\LLEY, SAN BERNARDINO COUN'1"{.
ADDENDUM 'l.'0 REPOR':::' OF SPECIAL S'l'UDIES ZONE INVES'l'IGATION, 50707 LAUREL 'l'RIL, MORONGO VALLEY, SAN BERNARDINO COUN'i'Y.
2. This project, identified by San Bernardino County as LG 0043 falls within the special studies zones as presently identified by your office.
Sincerely,
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owman, Jr. d Engineering Geologi
Depart nt of Building & Safet EPWA/Land Management Department
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REPORT OF SPECIAL STUDIES ZONE INVESTIGATION
507D7 LAUREL TRAIL PARCEL 584-211-12
MORONGO VALLEY SAN BERNARDINO COUNTY, CALIFORNIA
PREPARED FOR: Mr. David Peterhans 32-940 Cielo Vista
Cathedral City, California 92234
PREPARED BY: Southern California Soil & Testing, Inc.
Post Office Box 20627 6280 Riverdale.Street
San Diego, Californ1a 92120 l?~ ~ &O
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March 15, 1985
Mr. David Peterhans 32-940 Cielo Vista Cathedral City, California 92234
SCS&T 8531012 Report No. 1
SUBJECT; Report of Special Studies Zone Investigation, 50707 Laurel Trail, Parcel 584-211-12, Morongo Valley, San Bernardino County, California.
Gentlemen:
In accordance with your request, we have performed a geotechnical investigation of the subject site. A report of our findings is included herewith.
The findings of this study indicate that the Morongo Valley Fault is a few hundred feet southeast of the site but that no faulting is present at the subject site.
If you have any questions after reviewing the findings and recommendations contained in the attached report, please do not hesitate to contact this office. This opportunity to be of professional service is sincerely appreciated.
Respectfully submitted, SOUTHERN CALIFORNIA SOIL & TESTING, INC.
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Submitted County of San Bernardino, SCS&T, Palm Desert
Planning Department
BCIUTHERN CALIF"IJRNIA !!IJIL ANIJ TEBTINt'l, IN c.
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TABLE OF CONTENTS
PAGE Introduction and Project Oescription •••••••.••••••••.••••••••.•••••••••... 1 Project Scope .. ......... , ........... , .................................... . 1 Findings ....•.........••..•. , .........•......•.......••.......•........•.. 2
Site Description ...........•..........• ,, .....•........•...•....•.. .•. 2 General Geology and Subsurface Conditions ••••••••••••••••••••••••••••• 2
Geologic Setting and Lithology .••••••••• · ••••••••••••••••••••••••• 2 Tectonic Setting .........• ,., •......•....•..•••..••...••......... 3 Field Exploration .. , •.........•.......•...•....••......•••......• 3
Conclusions and Recommendations ..•• ,,, .......•...•...•••...•..•••.......... 3 Limitation .•...• , ........•.. , .......... ,., .................................... 4
Review1 Observation and Testing •.••••••••.•.•••••.••••••••...•••.••••. 4 Uniformity of Conditions ...••.•••••..•••.•••.••••••••••••••••••••••••. 5 Change in Scope ........................................................... 5 Time L1mitations .•.••..•.....••.•.•..........•.•..•...•...•....•..•••. 5 Professional Standard .•.•••••••••.••..••••••••••••••••••.•••••.••••••• 6 Cl ient•s Responsibility ..•..•....••••.•......•.•. , ...•..•..••....•..•. 6
References ....................................................................... 7
FIGURES F1gure 1
PLATES
Plate 1 Plate 2
ATTACHMENTS
Site Vic1n1ty Map, Follows Page 1
Plot Plan Trench Log
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GEOLOGIC INVESTIGATION
50707 LAUREL TRAIL PARCEL 584-211-12
MORONGO VALLEY SAN BERNARDINO COUNTY, CALIFORNIA
INTRODUCTION AND PROJECT DESCRIPTION
This report presents the results of our geologic reconnaissance for the subject site which is located 1n Section 27, Township 1 South, Range 4
East, SBBM in the Morongo Valley area of unincorporated San Bernardino
County. It is our understanding that the existing 5-acre parcel will be divided into two 2.5-acre parcels. We further understand that the existing
improvements on the western parcel will remain and that the other parcel will be dveloped with a single-family residence. A site vicinity map is
provided on the following Figure No. 1.
PROJECT SCOPE
This investigation consisted of: surf ace reconnaissance, on-site trenching using a backhoe, analysis of the field data, research of available
literature and aerial photographs pertaining to the site, and the
preparation of this report.
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SCS&T 8531012 March 15, 1985 Page 2
Specifically, the intent of our study was to determine whether any active faults were present at the site. This was done in accordance with the Alquist-Priolo Special Studies Zone Act which indicates generally that "No structure for human occupancy .•. shall be permitted to be placed across the trace of an active fault •••• (or) ••.• within fifty (50) feet of an active fault ••• ".
The Alquist-Priolo Special Studies Zone Act requires that the State Geologist delineate zones to encompass all potentially and recently active traces of any faults that may constitute a potential hazard to structures from surface faulting or surface creep. These zones are generally on the order of one thousand (1000) feet wide with the boundaries chosen so that the turning points coincide with locatable features in the ground.
FINDINGS
SITE DESCRIPTION
The project site is a square parcel, approximately 2.5 acres in size, that is located in the Morongo Valley area of unincorporated San Bernardino County. The site is legally described as Parcel 584-211-12 and is a portion of Section 27, Township 1 South, Range 4 East, San Bernardino Base Meridian. The site slopes gently to the south-southwest with an average elevation of approximately 2660 feet (MSLD). Drainage is accomplished both by sheetflow and in moderately to well defined drainage channels. The area of the proposed residence had been cleared of vegetation prior to our investigation; the remainder of the site supports a light to moderate growth of native shrubs, brush, and cactus.
GENERAL~GEOLOGY AND SUBSURFACE CONDITIONS
GEOLOGIC SETTING AND LITHOLOGY: The subject site ~s located in Morongo Valley which is thought to be a gral>en between the Pinto Mountain fault on the northwest and the Maronge Valley fault on the southeast. The site is
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SCS&T 8531012 March 15, 1985 Page 3
underlain by Quaternary alluvial depos1ts which are derived primar1ly from the granitic hills north of the site. The rate of uplift on the Pinto Mountain fault appears to be much greater than that of the Morongo fault thus creating a condition where the alluvial fan from the north extends across Morango Valley to the base of the hills on the south. The on-site sediments consist of brown to grayish brown, medium to coarse sands, gravelly sands, and sandy g,ravels.
TECTONIC SETTING: The Morongo Valley area is bounded by the Pinto Mountain fault, which is located approximately 8500 feet to the northwest of the subject site proper, and the Marengo Valley fault, located approximately 300 feet southeast of the subject site. The Morongo Valley fault is primar1ly a strike-slip fault with left-lateral movement and consists of a ma1n fault with several smaller en echelon faults. The main fault is approximately 300 feet southeast of the subject site and no evidence was encountered during our review of available literature, examination of aerial photographs, or on-site trenching to indicate that any of the smaller faults may exist at the site.
FIELO EXPLORATION
A continuous, northwest trending trench, approximately 180 feet long was excavated at the subject site on February 13 and 14, 1985. The trench was oriented in such a manner that it would intercept any northeast trending faults that might be present in the vicinity of the proposed structure. The trench was excavated to a depth of approximately ten feet, logged, and then backfilled. The location of this trench is shown on Plate Number 1 and the trench log 1s presented on Plate Number 2.
CONCLUSIONS AND RECOMMENDATIONS
1) The active Morongo Valley fault lies approximately 300 feet southeast of the subject site but no evidence of faulting was encountered at the subject site proper.
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SCS&T 8531012 March 15, 1985 Page 4
2) Based on the results of our on-s1te study and review of pertinent literature, it appears that the likelihood for surface rupture at the site should be considered to be nominal to nonexistent.
3) It should be recognized that groundshaking as a result of movement along one of the major fault ;::ones in the region is a seismic hazard which could affect the site. Groundshaking levels could range from low to severe depending on such factors as the magnitude and location of the event.
~ 4) The site appears to be suitable for residential purposes from an
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engineering geology point of view. The level of risk appears to be well within the acceptable range. However, it should be noted that structures should be located and constructed in accordance with the recommendations of a qualified soil and foundation engineer.
LIMITATIONS
REVIEW, OBSERVATION AND TESTING
The recommendations presented in this report are contingent upon our review of final plans and specifications. The soil engineer and engineering geolgist should review and verify the compliance of the final grading plan with this report and with Chapter 70 of the Uniform Building Code.
It 1s recommended that Southern California Soil & Testing, Inc. be retained to provide continuous soil engineering serv1ces dur1ng the earthwork operations. This is to observe compliance with the des1gn concepts, specif1cations or recommendations and to allow design changes in the event that subsurface conditions differ from those anticipated prior to start of construction.
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UNIFORMITY OF CONDITIONS
The recommendations and opinions expressed in this report reflect our best estimate of the project requirements based on an evaluation of the subsurface soil conditions encountered at the subsurface exploration locations and the assumption that the soil conditions do not deviate apprec 1 ably from those encountered. It should be recognized that the performance of the foundations and/or cut and fill slopes may be influenced by undisclosed . or unforseen variations in the soil conditions that may occur in the intermediate and unexplored areas. Any unusual conditions not covered in this report that may be encountered during site development should be brought to the attention of the soils engineer so that he may make modifications if necessary.
CHANGE IN SCOPE
This office should be advised of any changes in the project scope or proposed site grading so that it may be determined if the recommendations contained herein are appropriate. This should be verified in writing or modified by a written addendum.
TIME LIMITATIONS
The findings of this report are valid as of this date. Changes in the condition of a property can, however, occur with the passage of time, whether they be due to natural processes or the work of man on this or adjacent .properties. In addit1on, changes in the State-of-the-Art and/or Government Codes may occur. Due to such changes, the findings of this report may be invalidated wholly or in part by changes beyond our control. Therefore, this report should not be relied upon after a period of two years without a review by us verifying the suitability of the conclusions and recommendations.
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SCS&T 8531012 March 15, 1985 Page 6
:1 ·· PROFESSIONAL STANDARD 1 ' ' 'i In the performance of our professional services, we comply with that level
of care and skill ordinarily exercised by members of our profession currently practicing under similar conditions and in the same locality. The Client recognizes that subsurface conditions may vary from those encountered at the locations where our borings, surveys, and explorations are made, and that our data, interpretations, and recommendations are based solely on the information obtained by us. We will be responsible for those data, interpretations, and recommendations, but shall not be responsible for the interpretations by others of the information dev'eloped. Our services consist of professional consultation and observation only, and no warranty of any kind whatsoever, express or implied, is made or intended in connection with the work performed or to be performed by us, or by our proposal for consulting or other services, or by our furnishing of oral or
written reports or findings.
CLIENT'S RESPONSIBILITY
It is the responsibility of Mr. David Peterhans, or his representative to ensure that the information and recommendations contained herein are brought to the attention of the engineer and architect for the project and incorporated into the project's plans and specifications. It is further his responsibility to take the necessary measures to insure that the contractor and his subcontractors carry out such recommendations during
construct ion.
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SCS&T 8531012 March 15, 1985 Page 7
REFERENCES
Cal 1fornia Department of Water Resources, 1960, Data on Water Wells and Springs 1n the Yucca Valley-Twentynine Palms Area, San Bernardino and Riverside Counties, California, Bulletin 91-2.
California Division of Mines and Geology, 1974, Special Studies Zone Map, Southeast 1/4 Morongo Valley Quadrangle.
Dibblee, T. W. Jr., 1967, Geologic Map of the Morongo Valley Quadrangle, U. S. Geologic Survey Miscellaneous Investigations, Map I-517, Scale 1:62,500.
Hart, E. w., 1980, Fault Rupture Hazard Zones in California; California Division of Mines and Geology, Special Publication 42.
Jennings, C. W., 1975, Fault Map of California; California Division of Mines and Geology, Map No. 1, Scale 1:750,000.
Real, C. R., et al, 1978, Earthquake Epicenter Map of California, 1900 Through 1974, California Division of Mines and Geology, Map Sheet 39, Scale
1:1,000,000.
San Bernardino County, 1974, Seismic and Public Safety Element.
San Bernardino County, 1979, Aerial Photographs Flight C291, Photos 91-92.
United States Department of Agriculture, 1952, Aerial Photographs Flight l3k, Photos 61-62 and Flight 14k, Photos 109-110.
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May 28, 1985
County of San Bernardino Environmental Public Works Agency Land Management Department
SCS&T 8531012 Report No. 2
385 North Arrowhead Avenue San Bernardino, California 92915-9180
ATTENTION:
SUBJECT:
Gentlemen:
Lou Blanck
Report of Special Studies Zone Investigation, 50707 Laurel Trail, Morongo Valley, San Bernardino County.
We have received your letter of April 30, 1985 and have prepared this response to submit some clarifications needed concerning our original report. Our responses are numbered to correspond with the items in your review letter.
1. No map, other than the USGS Quadrangle Map, was available for our use. The owner had the corner points marked by a surveyor but no topographic map was prepared. Portions of San Bernardino County have
been mapped by the County at a sea le of 1: 2400 but the Morongo Valley area has not yet been mapped.
2. As explained to us by the property owner, the County of San Bernardino Planning Department required
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SCS&T 8531012 May 28, 1985 Page 2
a geologic report to address potential hazards from
surface faulting or fault creep as required by the
Alquist Priolo Special Studies Zone Act of 1972 but
did not require a full-scale geotechnical investi
gation. Consequently, secondary earthquake effects were not addressed. Based on our experience in the
area, it is our opinion that secondary effects such
as liquefaction, seismic-induced settlement, land
sliding, or groundshaking should not pose a signifi
cant hazard. However, it should be noted that a tho
rough investigation of the materials underlying the
proposed building location was beyond the scope of
our investigation and that said opinion is based
solely on our experience and not on a site-specific
geotechnical study.
3. A complete analysis of groundshaking hazards was
beyond the scope of our investigation. It should be
noted that several faults are located sufficiently
close to the subject site so that they could be the
source of seismic shaking. The San Andreas Fault,
the longest and most studied fault zone in Cali
fornia, is approximately 5 miles to the southwest.
Other Quaternary-age faults which could possibly
affect the site include, but are not necessarily
limited to the following: The San Jacinto Fault, the
Helendale Fault, the Lenwood Fault, the Emerson Fault
and the Calico Fault.
4. The project site consists of a 5-acre parcel,
approximately 330 feet north to south by 660 feet
east to west, that is to be divided into two 2.5-acre
parcels, each 330 feet square. An existing single
family residence is present on the western 2.5-acre
parcel. Figure No. 1 shows the entire 5-acre parcel
while Plate No. 1 shows only the eastern 2.5-acre
SCS&T 8531012 May 28, 1985 Page 3
parcel. The southeastern end of the trench shown on
Plate No. 1 is approximately 80 feet west-northwest
of the southeastern corner of the subject site.
SA. The trench shown on Plate No. 1 strikes approxi-
mately N55W.
SB. The scale of the trench log on Plate No. 2 is 1
inch ~ 10 feet.
SC. From Station O to Station 11, there were dis
tinct depositional features that could be followed to
help determine that no offset was present. From Sta
tion 11 to Station 16, the native materials were
characterized by a sandy gravel unit with no sign
ificant bedding features which could be followed for
any appreciable distance. It is therefore not pos -
sible to state unequivocally that this unit is not
faulted but rather to say that no evidence of fault
ing (such as fractures or displaced cobbles) was
noted.
50. Station 16 is the end of the trench. The trench
was terminated at this point because of the proximity
of the petroleum line and the lack of depositional
features exposed in this portion of the trench. It
is possible that a minor fault might be present west
of the trench that could be on oriented in such a
manner that it would intercept the proposed building
pad location. However, based on the strike of the
main trace of the Morongo Valley fault and the dis
tance from the main trace to the proposed building
pad location, the possibility of such a ,fault that
might traverse the building site appears to be low.
SCS&T 8531012 May 28, 1985 Page 4
If you have any questions regarding this report, or if we may be of further service, please do not hesitate to contact our office.
Respectfully submitted, SOUTHERN CALIFORNIA SOIL & TESTING, INC.
Curtis R. Burdett, CEG 1090
CRB:pp cc: (3) David Peterhans
(1) County of San Bernardino (1) SCS&T, Palm Desert
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7 8 I I
- ·.·.· .·, ..... · .··.·.-.' :··.-·. -.. -.·:·:~· ~·-. .:.-~: .. ·
G d s f Sand roun ur ace
I 13 14 15 16 l I I I
End of r Trench
~ SOUTHERN CALIFORNIA SOIL & TESTING, INC.
BY CRB DATE 5~29~85
I.JOB NO. 8531012 Plate No. 2
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SOUTHERN OA.LIF'LIRNIA 5C1L. AND TESTING, INC:.
P.O. SOX 20627 SAN DIEGO, CALIF, 92120
"14-1!!1:!111 Vl!!LIE WAV PALM Dl!:Bl!!RT, CALIF", 92260 TELE :il46-1Cl7liil
4"1~ 11;N"l'~Rltllli!.!lm;; .!IT• l(.!ICCllNDIDO, CAL.IF". •2112~ •TEL.Ii:: "/4 .. •4Clo44
July 15, 1985
County of San Bernardino Environmental Public Works Agency Land Management Department 385 North Arrowhead Avenue San Bernardino, California 92915-9180
Attention: Lou Blanck
SCS&T 8531012 Report No. 3
SUBJECT: Addendum to Report of Special Studies Zone Investigation, 50707 Laurel Trail, Morongo Valley, San Bernardino County.
Gentlemen:
We have recieved your letter of July 5, 1985 and are herein submitting
additional information as requested. with the items in said letter.
Our items are numbered to correspond
1) To date, the ends of the trench have not yet been located by a licensed surveyor. As suggested as a interim solution, we are providing distance and bearing from the southeast corner of the property. The southeastern end of the trench is 85 feet from the southeastern corner of the property at a direction measured as N65W. It should be noted portion of the site where
that our investigation covers only that the proposed building pad is located.
S 0 LI T H E: R N OALIFDRNIA SOIL ANO TE::!:JTINl'.5, I N r:.
SCS&T 8531012 Ju1y 15, 1985 Page 2
2 & 3) The San Bernardino County Seismic and Public Safety E1ement identifies the site as being in Seismic Hazard Zone Ill-B which
indicates that the minimum expected ground acceleration may be
0.4g or greater. The maximum bedrock accelerations that would be
attributed to a maximum probable earthquake occurring along the nearest portion of selected fault zones that could affect the site
are summarized in the following table.
Maximum Probab1e Maximum Bedrock
Fault Zone Distance Earthguake Acceleration
Morongo Valey 0.1 mile 6. 0 magnitude 0.6g
Pinto Mountain 1.5 mi 1 es 6.0 magnitude 0.6g
San Andras 4 miles 7.5 magnitude 0.6g
San Jacinto 25 miles 7 .3 magnitude 0.2g
Design accelerations are commonly a fraction (usually 2/3) of peak
bedrock accelerations.
Possible groundshaking levels at the site could range from slight to severe depending on such factors as the magnitude of the
the epicenter. It is likely
the effects of at least one
seismic event and the distance to
that the site will experience
earthquake during the life of the proposed structure.
Conventional,
normally able than those
one or two-story, wood-framed structures are
to withstand accelerations several times greater specified in the Uniform Building Code without
experiencing significant structural distress.
Other seismic related hazards such as tsunamis, seiches,
1iquefaction, earthquake induced flooding, ground lurching, and
seismic induced settlement or differential compaction should be of
no concern to the project.
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SCS&T 8531012 July 15, 1985 Page 3
Sc)
Non-seismic geologic hazards which may affect the site include
erosion of the unconsolidated native materials and flooding as a
result of strong desert storms, Other potential non-seismic hazards such as landslides, hydrocompaction, or volcanic activity
should be considered negligible or nonexistent.
Bedding features such as sediment lenses or cobble layers in the
portion of the trench from station 11 to station 16 were so
indistinct that sufficient overlap to show continuity was not
observable. Any such continuity shown on the trench log of this
portion of the trench would consequently be more in the eye of the observer than that displayed in the trench wall. It is possible
that sufficient continuity could be observable in another trench located a short distance north or south of the original trench but
it is questionable whether the probability of encountering such
continuity would justify the additional expense.
5d) Our May 28, 1985 letter indicated that it is possible that a minor
fault might be present west of the trench that could possibly
intercept the proposed building pad location. If such a fault
were present, it would be a minor secondary fault and in our
opinion would not be capable of causing surface rupture. Based on such factors as the distance to the main trace of the Morongo
Valley Fault and the lack of fault-related features exposed in the
exploratory trench, it is our opinion that the probability of a
secondary fault in this area is relatively low. Further
information on such faults could be obtained by excavating a
second trench, parallel to the first trench, north of the proposed
building pad and a third trench, west of the proposed building pad
and parallel to the gas line-petroleum line easement. It appears
that the cost of obtaining this information would not be
cost-effective but we realize that special criteria are sometimes applicable to Alquist Priolo Special Studies Zones.
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SCS&T 8531012 July 15, 1985 Page 4
If you have any questions regarding this report, or if we may be of further service, please do not hesitate to contact our office.
Respectfully submitted, SOUTHERN CALIFORNIA SOIL & TESTING, INC.
Curtis R.Burdett, CEG #1090
CRB :nr cc: (2) Submitted
(3) David Peterhaus (1) SCS&T, Palm Desert