'[50URCES AGfNCY G[ORCE D~U!i'.MFJIAN, ---······-·· Dr ... · 3/4/1985 · lies immediately south of Huntington Drive, but it would he helpful if future reports cont~ined

5TATE OF CAllF0~~41A· TtlE l\'[50URCES AGfNCY G[ORCE D~U!i'.MFJIAN, Govi!ftrro0F----······-··

Dr·PARTMENT OF CON~,fRVATlON

flP 1816 DIVISION OF MINES AND GEOLOGY BAY AREA REGIONAL OfflCE ~ao CIVIC DRIVE. SUITE 100

PlfASANT Hill, CA 945:J'3-l997

PHONE: {415} 6/l-4970

County Engineer-Facilities Engineering Geology Sectj_on 5~0 So~th vern1ont Avenue, Room 108 Los Angeles, CA 90020 Attn: Art Keene

near Art:

seplember 9, 1985

We are placing on open file thP. following reports, rP-viewed by the Co1lnty of Los Angeles in compliance with the Alquist-Priolo Spacial studies zones Act:

1~ Fault line investigation at 11920 South San Pedro Str~et, Building Pad A, Counly of Los Angeles, CA; by Hay A. Eastman; July 16, 1985.

2. Goo]ogic report, Tnnt~tive Tract 43726, 8814 Huntington Drive, San G.,briel, CA; by H.G. Hawkins; 6/25/85.

Geotechnical engineering report, Tax Parc~l 3004-016-015, LOS Angeles County, CA; by Buc::na Engineers, Inc.; March 4, 1985.

4. Geologic l1azards investigation, Parcel Map No. 11478, Lots 2, 3 & 4, Soc. 9, T.s.N., R.llW., LOS Ar1geles county, CA; by W.H. Park; July 1985.

PlGa.se note that report NO. 2 la-cks a location ma.p, which limits our ability to locate the site and trenches on our index map. I presume that the site lies immediately south of Huntington Drive, but it would he helpful if future reports cont~ined a useful index map.

EWH: rfq

cc: A-l' file (4) v

Sincerely yours,

Earl w. Hart, CEG 935 Senior Geologist & Program M,1nager

!ENGINEEFUNG GEOl.OGY SECTION

(213) 738-21131

(' • . .Act/PM _____ _

GEOLOGIC REVIEW SHEET COUNTY OF LO.$.ANGELES

DEPARTMENT OF ENGINhR-FACILITIES 550 SO. VERMONT AVE .. LOS ANGELES. CA 90020

Site Address • .. 7 7~17 -::;y:; ,o/, Location ~, ... .JJ.:i;.f.'{,/p_'l<-=------.. ·--·····----------~-----Geologist &e11n C'1f7-0 • ..:::z::z;..c • Developer/owner /. OCo><"<>C Soils Engineer______ Engineer :Z: A ,,,1~/sc,1'\

PLAN CHECK NO. OR DATE OF REi'ORT(S)

Review of:

Dist. Office fi 17 F NF ~X~_,...1.,,_ SHEET OF I

/

DISTRIBUTION: ~ist. Engineer .1 Geologist _ Soils Engineer l_ Geol. Sect. Fil<l.- Grading Section

OGrading P.c. No. --zv=-,';hi,.---,,r----------------------------"8.Building P.C. No._<'. -~~(.,.&~1"~&~,.,.J______________ --OGeologicSite Inspection On .. l.y:...;.,i PC. J.?o ---==-~-~~

Action:

'

( ··,~ ...

.gj:Geologic Report Dated _/fi'"U'( ."-'h__,'/'-.,=r-"/'-(/,L<~°'\~---'23<-L_-_,;i.;,,,· ,...3 .. 3"'-L_-.._?...,o"-]~---_ -_ ---------_ -_ -_ -_ -_----· ··--·--0 Soils Report Dated .. __ --------------------""---·· OGeology & Soils Report Dated _____ _

D Plan isg<>ologically approved

jZ] Plan approved geologically subject to conditions below

~c. 309 Code requirements met '""Ui 1 etl OSec. 308(b) 3c & e code requirements met (not met)

D Plan is not approved for reasons below

OSubmit plans for recheck

fr1m~

<:.iared by __ · tfl~,,.,.._....,4...,a""""~-..,;~;::c:.=... ____ Reviewed by,.~ ,f! ~ Date

76GJOA - PS 9-84

' ' ; l

r [

L ! ' ~ ..

, ..

' , ..

'

I .

L L j '···

L

3/ L_}3(. . (jG \j)/Qc__e

'?C_* !-/-CJ 7 ~

lul!na Engineers,lnE. ~·

IODSULTIDG SOILS B. EDGIDEERIDG GEOLOGY

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

Engineers, ln1.

42326 - 101h STREET WEST • P.0- BOX 2866 • L-ANCASTEA, CAllFORNIA 93534 • PHONE (805) 948-7538

March 4, 1985

Mr. Terry O'Conner 2514 Poker Plant Court Palmdale, California 93550

Dear Mr. O'Conner:

Subject: GEOTECHNICAL ENGINEERING REPORT Tax Paree I 3004-0 16-0 15 Los Angeles County, California

B-2339-LOI

Presented herewith is our Geotechnical Engineering Report performed as authorized for the subject parcel located near Palmdale, Los Angeles County, California. Based on the data collected for this report, it is our opinion that the site is suitable for its intended use as a single-family homesite provided the recommendations of the following report are complied with.

Recommendations for general site development with respect to observed site geologic and so11 conditions are included. The conclusions and recommendations contained herein were based upon the applicable standards of our profession at the time this report was prepared.

This report completes our scope of services in accordance with our agreement dated May 1 o, 1984 and authorized by Mr. Terry D. O'Conner on February 8, 1985. Additional services which may be required, such as plan review and grading observation are addition;:il servk"!S and will be billed according to the Fee Schedule in affect at the time the services are provided.

eNGINEERING OFFICl:S;

FIE.LO OFFICES:

VENTURA (805} .. 2-6727

THOUSAND DA~S 1806)495-S<M

SANTA BARBARA 180/l) 966-9<m

PALM SPRINGS (714) 328-9131

LANCASTER (805) .... 7538

SAN LUIS OBISPO (805) 544-6187


Please contact the undersigned If there are any questions concerning this report or the recommendations Included herein

Respectfully submitted,

BUENA ENGINEERS, INC.

~r! Mark S. Spykerman RG. •3800 C.E.G ... 1174

cc: 6 - CJ ient 1 - VTA

BUEMA EMGIHEERS, IMC.

~f£u--Raymond E. Brannen C.E.•28966

I I I I GEOTECHNICAL ENGINEERING REPORT

I TAX PARCEL 3004-016-015

I PALMDALE. CALIFORNIA

I I I PREPARED FOR

I MR. TERRY O'CONNER

I I I B-2339-LOI

I MARCH 4. 1985

I I I I I ~



TABLE OF CONTENTS

PAGE

INTRODUCTION .......•......••..............................................•................ I SITE DESCRIPTION ......••••••..••.••••...............•...•...••..........••.••.......•... I FIELD EXPLORATION ......••..................•..••.•••..............••...•.....•......... 2 6EOL06 IC SETT I N6 ••••••............••.•.••••••••.•.......••••••..••.•...............•.•.• 2 SITE GEOLOGY ..........................••••.•............•••••••.............•.•••••••••••... 3

Descr1pt1Ve Geology •••..••.•••..................•••••..............•...•••••.••••.•.. 3 Quaternary Harold Format1on •..•............•••.••..•....•.•.............•. 3 Quaternary Older Alluvium .........•.•••........................•..•...••.•.. 4 Quaternary Younger Alluvium .•.•••..•...............•....•................. 4

Faults .........•..•.....•••••.....•..............•.•.•.....................•................• 5 GEOLOGIC HAZARDS .•••...............•..•...•...........•••.•....••.•..............•.••. 5

Fault1ng •••••.............................••.............••..•.•...••.•..............••..... 5 Ground Shak 1 ng .•.....•••.••••••..............•••.•....................••••............. 6 Liquefaction ••.•.••.....................•................•.•••....••..................••• 7 Other Hazards .....•.•••.••.•...•................•....................................... 7

CONCLUSIONS .••••....................................................•....................... 7 RECOMMENDATIONS .........•...•.............................................•........ I 0 ADDITIONAL SERVICES ............................................•...•.•............ 12 LIMIT AT IONS ANO UNIFORMITY Of CONDITIONS •...................•. 12 REFERENCES .................•........••.............••••..••••............................. 15

APPENDIX A Regional Fault Map - Plate I Site Plan & Geologic Map - Plate 11 Log of Exploration Trench - Plate Ill

APPENDIX 8 Standard Grading Specif1cations

~



March 5, 1985 B-2339-LOl

GEOTECHNICAL ENGINEERING REPORT

TAX PARCEL 3004-016-015

PALMDALE, CALIFORNIA

INTRODUCTION

This report presents a summary of our geology services for the subject parcel located near Palmdale, Los Angeles County, California. The report was prepared in accordance with authorization by Mr. Terry o·conner on February 8, 1985. The purpose of our services was to review the site geologic conditions and provide comments and recommendations relative to the proposed site development and observed geologic hazards.

Current plans call for the construction of one conventional type single-family residence in the southwest portion of the lot. Minimal site grading is anticipated with planned sewage disposal by on-site septic tank and leachfield. The site geologic conditions were evaluated in the field and through selected technical publications. Conclusions regarding the site are based on the data collected and form the basis for the recommendations presented.

SITE DESCRIPTION

The :!:2.3 acre lot is located approximately 1,600 feet north of Avenue 5 and 1,300 feet west of Tierra Subida Avenue. in Anaverde Valley, Palmdale, California. The lot is described as the N 1/2 of the S 1/2 of the E 1/2 of the W 1 /2 of the N 1 /2 of the SW 1/4 of Section 34, T6N, R 12W, SBBM. Access to the site ls via Avenues, 7th Steet west, Avenue R-12, and Tye Place. Tye Place is a well graded dirt road that terminates at the southeast comer of the site.

Topographically, the site can be divided into two areas. The southwest half of the site is relatively flat and level. The northeast half of the site lies



March 4, 1985 2 B-2339-LOI

lower than the southwest half and consists of rugged topography with incised drainages, low ridges and knowles. Drainage in the southern portion of the site is generally by sheetflow. In the northern portion of the lot, runoff is directed to many well defined drainage courses which divert the surface water to the north.

Vegetation consists of typical desert plants including abundant junipers, Joshua trees, shrubs, and grasses. At the time of our field exploration, the site was vacant. Existing improvements included survey markers at al I property comers, and several dirt trans than cross the southern portion of the site. In addition, the proposed building site had been marked in the field via four stakes outlining an area roughly I 00 feet square.

FIELD EXPLORATION

The fie Id work for this project was conducted on February 25, 1985, and consisted of a site reconnaissance and excavation of one exploration trench across the proposed building site. The trench was 181 feet in length and extended approximately five to ten feet below the existing ground surface. The approximate location of the trench is shown on the Site Plan, Plate II.

The trench was excavated with a tractor mounted backhoe and was oriented approximately perpendicular to the general trend of faulting in the area. Portions of the walls and bottoms of the trench were cleaned of loose or smeared soil and graphic log compiled illustrating the approximate locations and orientations of pertinent features observed. The log is included on Plate 111 of this report. Previous geologic data prepared by Barrows. et al ( 1976) and personel from this firm was also utilized to aid in interpretation of the site geology.

GEOLOGIC SETTING

The project site ts located at the base of the Sierra Pelona in Southern California. The Sierra Pelona are a part of the Transverse Ranges which extend in a southeast-northwest direction across Southern C:>lifornia. Rocks composing the Transverse Ranges consist of an extremely complex group of folded and faulted rocks varying from pre-Cambrian gneisses to modem allwial deposits. North of the Sierra Pelona is a vast area of desert basins



March 4, 1985 3 B-2339-LOl

and mountain ranges comprising the Mojave Desert where pre-Cambrian, Paleozoic, and Mesozoic rocks are encountered along with Cenozoic lake and fluvlal deposits. Dividing the Sierra Pelona from the Mojave Desert is the San Andreas rift zone.

The San Andreas rift zone, which is up to several miles wide, dominates the landscape in the Palmdale area with classic fault features and geologic structure. The rift zone is an extensive zone of active and potentially active faults that extends for approximatley 800 miles from the Gulf of Callfornla to Cape Mendocino in Northern California. Right lateral offset of many streams and gullies averaging 10 to 13 feet apparently records the most recent fault movement along this portion of the main trace of the San Andreas fault.

Abundant smaller active and potentially active faults within the San Andreas rift zone lie north and south of the main trace of the San Andreas fault. These include the Little Rock fault, Cemetery fault, Nadeau fault, and abundant subsidiary faults. Quaternary movement is locally evident along these faults.

SITE GEOLOGY

The subject lot is located within the San Andreas rift zone, more specifically between the southern projection of the Nadeau fault zone and the main San Andreas fault. Differential movement within the zone has resulted in the irregular topography and the deformation and faulting of lithologic units. Regional llthologic units consist of Cenozoic sediments and sedimentary rocks overlying pre-Tertiary granitic rocks.

Descriotjye Geology

On-site lithologic units encountered on the subject parcel consist of Quaternary alluvial deposits overlying Quaternary sedimentary rocks. Descriptions of the units encountered are as follows:

Quaternary Harold Formation (Pleistocene): Undifferentiated deposits of debris derived from local sources consisting of poorly consolidated fluvial sands, silts, and gravels. Colors are generally light due to abundant



March 4, 1 985 4 B-2339-LO 1

caliche (calcium carbonate) found as lenses, coatings and seams within the formation. This material is exposed in the northern portion of the site where the overlying older and younger alluvial deposits have been removed by erosion.

Quaternary Older Alluvjum (Upper Plejstocenel: Tan to light brown silty fine to medium sand with variable quantities of gravel. The deposits are generally moderately to well cemented and dense, although the deposits are typically moderately to highly voided. The older alluvium was encountered in the exploration trench excavated across the proposed building site and Is generally buried by several feet of younger alluvium.

Quaternary Younger Alluvium (Holocene): Dark brown very silty fine to medium sand that is poorly bedded and generally medium dense. The younger alluvium appeared to be only slightly voided, and generally varied from three to five feet thlck where observed in the exploration trench. Based on past experience in the area, this soil exhibits a slight to moderate potential for hydroconsolldation. The younger alluvium is encountered in the southern portion of the site as well as in the northern part of the site within the local incised drainage courses.

Faul ts

The project is located within the San Andreas rift zone which in this area includes the San Andreas, Little Rock, and Nadeau fault zones. The subject parcel is located between the Nadeau fault zone and the San Andreas fault zone with the San Andreas fault located 600 feet northeast of the proposed building site, the Little Rock fault 2,000 feet northeast of the site, and the Nadeau fault 1, I 00 feet southwest of the site. All referenced distances are approximate. A Regional Fault Map showing the approximate locations of the Identified faults is presented on Plate I of thls report.

The active main trace of the San Andreas fault is readily apparent in the · Palmdale area due to the presence of abundant fault features such as aligned ridges and valleys, sag ponds (Lake Palmdale), and offset drainages. The fault is characterized 2: a near vertical strike-slip fault with right lateral movement.

The Little Rock fault zone. located north or the site is considered subsidiary



March 4, I 985 5 B-2339-LOI

to the San Andreas fault with movement within the Little Rock fault zone most likely occurring sympathetic to movement along the San Andreas fault. The Nadeau fault located south or the subject property Is also considered subsidiary to the San Andreas. These faults are classified by the State as potentially active with some segments showing evidence of Holocene displacement, possible associated with movement along the San Andreas fault in 1857.

Based on data from previous studies by this firm and the California Division of Mines and Geology, there are several subsidiary faults to the San Andreas that are located to the east of the lot. The projected trend of these faults would cross the lot through the northeast portion of the site In the area north of the promlnant break in slope. No evidence of fault activity was observed in the exploration trench excavated across the proposed building site (southwest portion of site). The cemented older alluvial deposits exposed in the trench probably pre-dates the Holocene (last 11,000 years) and did not appear to be disrupted.

GEOLOGIC HAZARDS

Geologic hazards which may affect the proposed land development include potential fault rupture, other earthquake related hazards, and minor flooding and erosion. Due to the relatively moderate topography, and lack of steep slopes, hazards due to landslides or slippage are considered negligible.

Faulting

For the purposes of this report we evaluated the potential fault hazard in the immediate vicinity of the proposed building site located in the southwest portion of the lot. No evidence of active faulting was observed in the exploration trench. It is therefore our opinion, that the delineated proposed building site as observed In the field on February 25, 1985 has not been subject to past active fault rupture. This opinion ls based on the lack of geomorphic evidence for fault rupture in the vicinity of the building site and the data obtained from the exploration trench.

However, in the northeast half of the lot, the topography changes abruptly from the flat and level terrain in the southwest half of the lot to deeply



March 4, I 985 6 B-2339-LOI

incised drainages and rugged hi tlsides that are characteristic or the fault zone. Although we did not specificatly evaluate the potential fault hazard in the northeast half of the Jot by trenching, it ls suspected that several subsidiary faults may be located In this area. Construction of structures over or immediately adjacent to the any fault in this area may be subject to potential differential movement during a major earthquake occuring along this portion of the San Andreas fault zone. Ground lurching, defined as ground cracking with permanent soil deformation witl most likely occur immediately adjacent to active faults.

Ground Shaking

A primary geologic hazard relative to site development is considered to be ground shaking resulting from a major earthquake originating on the San Andreas fault. The last major seismic event (relating to the San Andreas fault) felt in the Palmdale area occurred in 1857, during the Fort Tejon Earthquake. The event was estimated to have had a Richter magnitude of 8.25 and was felt throughout much of Central and Southern California. Fault rupture along the San Andreas fault zone ocurred near Parkfield, California, to Cajon Pass with relative offset across the fault of Io to 30 feet. Modified Mercalli intensities felt during the earthquake in the Palmdale area are estimated to have ranged from approximately VII to VIII.

Significant earthquakes have occurred on other faults in Southern California which have been felt in Palmdale. These include the 1872 Owens Valley earthquake (Modified Mercall i intensity at Palmdale of VI), I 952 Arvin-Tehachapi earthquake (VII), and I 971 San Fernando earthquake (VI).

Based on the hypothetical great earthquake similar to the 1857 event (Davis, 1982), the Palmdale area could experience Modified Mercalli intensities as great as IX. Significant earthquakes originating on faults in Southern or Central California other than the San Andreas are expected to have intensities at Palmdale of less than IX.

It should be noted that the level of damage described by the Modified Mercalli Scale 1s based on past experience of a given earthquake on buildings not necessarily designed to current standards. Damage to structures designed to current standards is expected to be less. However, possible structural damage should be anticipated to buildings within this area due to potential

~

BUENA ENGINEERS. INC.


March 4, 1 985 7 B-2339-LOI

severe ground shaking. A description of the damage which can be anticipated based on the Modified Mercalli Scale is presented on Table I of this report.

Using data from Sieh <I 978) relating to the recurrence Intervals or major seismic events on the San Andreas fault, it is estimated that a major earthquake has occurred along this segment of the San Andreas fault every 100 to 200 years. The average recurrence interval Is estimated to be 140 years. As the last major earthquake on the San Andreas fault in this area occurred in 1857, the occurrence or an earthquake in this area within the estimated lifetime of any new construction Is considered likely.

Li guef action

Liquefaction is the loss of strength of saturated cohesion less soils generally due to seismic shaking. As the material underlying the site consists of variably cemented alluvial deposits with ground water depths in excess of fifty feet below the surface, it is our opinion that the potential for liquefaction at the site is negligible.

Other Hazards

Other hazards include erosion, flooding, and settlement due to hydroconsolidation. Minor sheet flooding and erosion could occur at the site due to local intense rainfall. However this hazard can be mitigated by appropriate site grading and maintenance.

Based on consolidation tests performed on the nearby soils, it appears that the alluvial soi Is underlying the site may experience variable amounts of settlement due to hydroconsolidation. Remedial measures are recommended to minimize this hazard.

CONCLUSIONS

Based on the fleld reconnaissance, trenching, and literature review, it is our professional opinion that the primary geologic hazards relative to site development for residential purposes are ground shaking, minor flooding, and erosion. No obvious ground rupture or other evidence of recent ground movement was observed across the delineated "Building Area·.



March 4, 1 985 8 B-2339-LOI

Modlll9CI Mercem lnteneltr Sc•I• ol 1931 •, (11H .,erslon)I

Masonry A. B. C, D. To avoid ambiguity of language, the quality of masonry. brick or otherwise, Is specified by the following lettering.

Masonry A. Good workmanship. mortar, and design; reinforced, eopecially laterally, and bound together by using steel, concrete, etc.; designed 10 re1ist lateral forces.

Masonry B. Good workmanship and mortar; reinforced, but not designed In detail 10 resist lateral force•.

Masonry C. Ordinary workmanship and mortar; no extreme weaknesses like failing lo tie in al corner•. but neither reinforced nor designed against horizontal forces.

Masonry 0. Weak materials, such as adobe; poor mortar; low 81andards of workmanship; weak horizontally.

L Not !eh. Marginal 1nd lonQ'1)8rlod err.eta ol llrii• 11nhquak11.

n. Fett by P"f*'na 1t real, on upper !too,., or ta'IOrably pl1C1d.

m. Fett Indoor.. Hanging objacta awing, Vibration Ilk• pa11lng of llghl lrucl<a. Duration estlmatld. May not be r1eognlzed 11 on eanhquak•.

IV. Hanging objectl awing. Vibration like pa111ng of heavy trucu; or aen11tlon of a jott llke a heavy boll striking the wati.. Standing motor cara rock. Window&, dishes, dOOra rltlle. Glaa111 clink. Crockery cllllhH. In the upper range ol IV wooden wali. ind frame cre1k.

v. Fett ouldoora; dlroctlon eallmatld. Sleepera w1kened. Uqulda dlllurbed, tome t1>llled. Small un-II.Cle objacta dioplaced or upeal. Doora owing, cloae, open. Shutto,., picture& move. Pendulum

• clock• .top, at.an, chang• rate .

VL Fatt by all. Many trtghtenld and run outdoo ... Peraona wolk unlleadlly. win-. diallea, glaaawa .. broken. Knlckknack1, book•. etc., oK th•lw•. Plctur•• off wells. Fumtture moved or O\lerturneo. Weak plaator ond masonry D crockld. Small bella ring (church, achoo!). Trees, bullll•• atioken •l•lbly, or heard to rullle.

Vil Olftlcult to 1t1nd. Noticed by driv•r• of motor cars. Hanging ob)ectli quiver. Furniture brok•n. Damage to maaonry 0, Including cracks. W••k chimneys broken •t roof line. Fall of p\aater, loote bricks, •one•i tnn:, comic•• •leo unbraced parapet• and architectural om.amenta. Some cracks in maeonry C. waw1 on pond•: waler turbid with mud. Small elld•• anCI caving In •k>ng unct or gravel banka. Largo bells ring. Concrete lrriQ1tlon dttchea damagad.

VIII. StHrlng ot motor cart affected. Damage ro rnuonry Ci pantal collapte. Some damage to ma.onry B; none to muonry A.. Fall of etucco and a:>me ma.onry walls. Twlltlng, fall of chimneys, f•ctory ltac=k•, inonumenra. towera, etevat.cl tank•- Frame hou•• moved on foundation• II not betted down: loCll panel walls thrown out. Doc1yed plllng b<Oken off. Branche• broken from trees. ChanOH ;n flow or temporsture ol t1>rlng1 Ind wells. Crack• In wet ground ind on ateep tlopes.

IX. General panic. Maoonry D dHtroyed; mltonry C llMYl!y damagad, 10metlmH with complelll coll•i>M: mallOnf'Y B "riouaty damagtd. General d1mege to found1t1ona. Ft1me •ructurea. lf not bolted, lhlftld oll lound1tlon1. Frameo rocked. Serious damage to ,...,..,Ira. Underground plpH broken. Contpk=uou• crack• In· ground. In alluvt•ted areas .. nd and mud ejeetedt •arthQuak• fOun-taint, und cratert.

x. Moat m-nry 1nd frame structures daotroyed with their foundation•. Some -n-bulft wooden llruc-turea and bridge& deatroyea. Serlou• damage to dama, dlkn, ombankmentl. Large landalldH. Water thtown on bank• of cane.ta, rNere, lakn, etc. Sand and mud shift.cl hOrizontalty on beaches •nd 1111 19nd. Flllls bent •llOhtly.

XL Aali. bent greatly. Underground plpellneo completllly out or oerYlce.

XD. Demaga nearly tolll. Lariie rock ,.. .... , dleplaced. Linea ol 1lght and -I dloltartld. Objec,. thrown Into the air. •

1 0riglna11va1 ""''ion in Wood, H. O .. .nd Neum.,n. F., 1$31, Modlliitd ... erealli int.n1lty -.cal• of 1031: SNmolOgk:•I Srx:iety Df Amtir~t Sult.tin, ..-. sa, no. :5. p. 919-081.

~1956 vtn.icn Pi'IPlf..:I by Cl'lari.s F. R.icl'lt•t, lrt ElflmMtl'Y Seismology. 1$M, p. 1a1~13ft. W. H. Fr~man & Co.

Table 1. Modified MercaUi Intensity scale of 19311 (1956 versionr'


March 4, 1985 9 B-2339-LOI

If construction for human habitation is intended outside the area designated, additional exploration should be required to verify the absence of faulting at the additional building locations.

The site is located within the San Andreas rift zone Therefore, there is a potential for structural damage to any building in this area due to severe ground shaking. It is our opinion that a significant seismic event resulting from movement within the San Andreas rift zone may occur in this area in the lifetime of any new construction. Ground rupture would most likely occur along previously established zones of weakness. However, there ts no guarantee that ground rupture will not occur at other locations. Earthquake intensities as great at IX based on the Modified Mercalli Intensity Scale should be anticipated during severe seimic activity.

Possible minor flooding and erosion could occur in the vicinity of the site due to intense rainfall. Proper site management and grading can mitigate the flooding hazard.

On-site sewage disposal by leachfields should not adversly affect the geologic stability of the site provided the disposal fields are located in the flatter portion of the site.

Foundations for the proposed residence founded within the alluvial soils could experience differential settlement due to hydroconsolidatlon of voided soils. Remedial measures to minimize this hazard are recommended.

Based on the findings summarized in this report, it is our professional opinion that construction within the delineated "Buildable Area· will not be subject to a geologic hazard from settlement, slippage, or landslides provided the recommendations of this report are incorporated into site development.

It is also our opinion that the proposed improvements and anticipated site grading will not adversely affect the geologic stability of the site or adjacent properties provided the recommendations contained within this report are incorporated into site development. Test findings and statements of professional opinion do not constitute a guarantee or warranty, expressed or implied.



March 4, 1985 10 B-2339-LO I

RECOMMEND AT IONS

Based on the tield reconnaissance, exploration trench, and other data collected, the following recommendations are provided.

I. Any on-site construction for human occupancy should be confined to the designated "Bulldlng Area·. Additional trenching will be required for construction outside this area.

PLEASE NOTE: The exploration trench backfill is uncompacted and unsuitable for support of structures. If any structure or other improvements including paved access roads are located over or Immediately adjacent to the exploration trench, tt is recommended that the trench backfill be overexcavated and replaced with compacted engineered fill or the structure be designed to span the trench. Compacted soils should be placed in thin six Inch lifts and compacted to at least 90% of the maximum dry density as determined by the ASTM D 1557 test method.

2. Construction should allow for all plumbing and utility services to be connected with flexible connections and/or provided with convenient shutoffs.

3. Diversion and reduction of concentrated runoff should be provided to minimize erosion of on-site slopes and improvements

4. Leachfield disposal systems should be located to the east, west, or south of the residence location.

5. Grading plans, if required, should be in accordance with existing building codes. It is recommended that the project engineering geologist or his representative review the grading plans prior to construction and site development during the site grading phase only if a grading permit is issued.

6. Any site grading should be in conformance with existing building codes. Appendix B, Standard Grading Specifications included in this report, and Chapter 70 of the Los Angeles County Building Code contain specific considerations for grading and form a part of this report.



March 4, 1985 11 B-2339-LOl

7. The proposed residence location should be checked in the field prior to construction by the consulting geologist or building inspector to verify location within the ·sulldable Area·. Field review of building locations and site grading, If required, will be an additional exPense and will be billed at current fee scheduled rates.

8. Consolidation tests performed on soils taken from Tract No. 37864 located immediately south of the site indicated a slight to moderate potential for hydroconsolidation. As similar soils exist underlying the proposed building site, it is recommended that remedial measures be performed to minimize the potential hazard from soil settlement. These measures include the following:

A Prior to site grading, the surface should be stripped of organic growth, non-complying fill, and along with other debris removed to an area outside of the proposed building site.

B. Soils within the building area and areas to receive fill should then be excavated to a depth of three (3) feet below natural grade or finished subgrade whichever is lower. The resultant surface should then be scarified a minimum of twelve ( 12) inches.

In addition, the soils to a depth of at least 24 inches below the scarified surface should then be presoaked to a moisture content at or above optimum moisture content determined by the ASTM D 1557 test method.

C. The scarified soils should then be compacted to 90'1: of the maximum dry density as determined by the ASTM D 1557 test procedure. Engineered backfi 11 should then be placed in six inch lifts and compacted to 90 S of the maximum dry density until the desired finished grade is attained. The intent of these recommendations Is to have a minimum of four feet of compacted engineered fill under the building site. This site preparation should extend a minimum of five feet outside the exterior 11mlts of the proposed structure(s).

[' Footings should extend a minimum of 12 inches below finished grade for one story structures and 18 inches for two story buildings.

E. Footings should be reinforced with two •4 bars, one top and one


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March 4, 1985 12 B-2339-LOl

bottom. Concrete slabs should be reinforced with •3 bars placed in the center of the slab at 24 inch centers each way or 6" x 6" 1• 1 O x • 1 o welded wire fabric.

F. All roof draining systems for the proposed building should be designed so that runoff water is diverted away from the structure. Site grading should be such that water will not be allowed to pond or stand next to the foundation.

G. It Is suggested that irrigation systems should be provided with automatic shutoffs in order to minimize saturation of the underlying soil layers.

ADDITIONAL SERVICES

This report is based on the asumption that an adequate program of monotioring and tests will be performed during construction to check construction compliance with these recommendations. These tests would be additional services provided by our firm. The costs for these services are not included in our present fee arrangements. The recommended tests and observations include but are not necessarily limited to the following:

I. Consultation during design and construction.

2. Continuous observation and testing during site proparation, grading, and placement of engineered fill. Specific items which should be performed include:

a. Observation of foundation excavation locations.

b. Compaction tests to confirm the relative compaction or engineered fill.

LIMITATIONS AND UNIFORMITY OF CONDITIONS

The conclusions and recommendations submitted in this report are based in part upon the data obtained from one (I) exploration trench, site reconnaissance, and stereo aerial photo review. The nature and extent of

~ BUENA ENGINEERS, INC.


March 4, 1985 13 B-2339-LO I

variations from observed conditions may not become evident until construction. If variations then appear evident, It will be necessary to reevaluate the recommendations of this report.

A field log of the exploration trench was prepared by our geologist. The log contains information concerning the interpretation by the geologist related to lithologic description, stratigraphy, and structure. Therefore, the log contains both factual and interpretive Information. It must be emphasized that our conclusions and recommendations are based on the final log which represents our Interpretation of the features observed.

In the event that any changes in the nature or location of the proposed development are planned, the conclusions and recommendations contained in the report shall not be considered valid unless the changes are reviewed and conclusions of this report modified or verified In writing.

This report is Issued with the understanding that it is the responsibility of the owner, or of his representative to insure that the information and recommendations contained herein are called to the attention of the architect and engineers for the project and incorporated into the plan and that the necessary steps are taken to see that the contractors and subcontractors carry out such recommendations in the field.

It is recommended that the consultant be provided the opportunity for a general review of final design, grading plans (if required) and site grading in order that the earthwori< and structural recommendations may be properly interpreted and implemented in the grading and construction phase of the project. (If the consultant is not accorded the priviledge of making this recommeded review, he can assume no responsibility for misinterpretation of his recommendations).

The geotechnlcal consultant has prepared this report for the exclusive use of the Client and authorized agents. This report has been prepared in accordance with generally accepted engineering and geology practices. No other warranties either expressed or Implied are made as to the professional advice provided under the terms of this agreement, and included in the report.

It should be recognized that this report does not guarantee issuance of grading or building permits. My additional wori< which may be required after

"'&: BUENA ENGINEERS, INC.


March 4, 1985 14 B-2339-LOI

submittal of this report such as footing excavation and rough grading reviews Is not Included as part of our Initial agreement and will be billed at fee schedule rates applicable at the time of the additional wen.

We trust this report ts sufficient at this time. If you have any questions regarding this information or require additional studies, please contact us.

Respectfully submitted,


/Jl1d rj. Mark S. Spykerman R.G. • 3800 C.E.G. • I I 74

Appendices

BUENA ENGINEERS~INC.

~€4w---Raymond E. Brannen C.E. •28966

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March 4, 1985 15 B-2339-LOl

REFERENCES

1. Barrows, AG., Kahle, J.E., and Beeby, D.J., 1976, Geology and Fault Activity of the Palmdale Segment of the San Adreas Fault Zone, Los Angeles County, California, CDMG Open File Report 76-6 LA

2. Buena Engineers, Inc., 1979, Soll Investigation for Tentative Tract No. 37864, File No. B-1663-LO I, dated September 28, 1979.

3. Califomla Division of Mines and Geology, 1969, Geologic Map of Callfomia, Los Angeles Sheet.

4. , 1975, Ca11fomla Geologic Data Map Serles, Map No. I, Faults, Volcanoes, Thermal Springs and Wells.

5. , 1977, Fault Hazard Zones In California, S.P. 42, Revised January 1977.

6. , 1977, Active Fault Mapping and Evaluation Program, S.P. 47.

7. ----. 1978, State of California Special Studies Zone. Ritter Ridge Quadrangle.

8. Davis, James F .• et al, 1982, EarthQuake Planning Scenario for a Magnitude 8.3 EarthQuake on the San Andreas fault in Southern Califomia, C.D.M.G. Special Publication 40.

9. Dibblee, Thomas W. Jr., 1967 Areal Geology of the Western Mojave Desert, California, U.S. Geological Survey Professional Paper 522.

10. Noble, Levi F., 1953, Geology of the Pearland Quadrangle, California, U.S. Geological Survey, Geologic Quadrangle Map of the United States.

11. Sieh, Kerry E., 1978, Earthquake Intervals, San Andreas Fault, Palmdale, California, California Geology, June 1978.

12. Smith, Michael V., 1979, Geologic Hazards Study, Tentative Minor Land Division Number 12740, Palmdale, California, Fi le No. 7946-1, dated September 10, 1979.


I I I I I I I I I ~

I I I I I

_I

I I I

March 4, 1 985

AERIAL PHOTOGRAPHS

From: l.K Curtis Scale: 1:+12,000

16 B-2339-LOl

Date Flown: June, 1971 Frame •'s: 8180-8182


I March 4, I 985 17 B-2339-LOl

I I I APPENDIX A

I Vicinity & Regional Fault Map - Plate I

I Site Plan & Geologic Map - Plate 11

I Log of Exploration Trench - Plates Ill

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I March 4, 1985 18 B-2339-LOl

I I I

APPENDIX B

I Standard Grading Specifications

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



1.

2.

ST ANDA.RD GRADING SPECIFIC>. TIONS

These Standard Grading Specifications have been prepared for the exclusive use

of our dient for specific application to referenced project In accordance with

generally accepted soil and foundation engineering practices.

warranty, expressed or Implied, Is made.

No other

Buena Engineers, Inc., referred to as the soil engineer, should be retained to

provide continuous soil engineering services during construction of the grading,

excavation and foundation phases of the work. This is to observe compliance

with the design concepts, specifications or recommendations and to allow design

changes in the event that subsurface conditions differ from that anticipated

prior to start of construction.

3. The presence of our field representative will be for the purpose of providing

observation and field testing. Our work does not include supervision or direction

of the actual work of the contractor, his employees or agents. The c;ontractor

for this proje<;t should be so advised, The contractor should also be Informed

that neither the presence of our field representative nor the observation and

testing by our firm shall excuse him in any way from defects discovered in his

work. It is understood that our firm will not be responsible for job or site safety

on this project. Job and site safety will be the sole responsibility of the

contractor.

4. H the contractor encounters subsurface conditions at the site that (a) are

materially different from those indicated in the contract plans or in

specifications, or (b) could not have Ileen reasonably anticipated as inherent In

the work of the character provided in +he contract, the contractor shall

immediately notify the owner verbally and in wdtlng within 211 hour• This

notification shall be a condition precedent before any negotiations for nchanged

or differing site conditions" can proceed. If the owner determines that .,

l


2

cQl'lditions do materially so differ and cause an increase or decrease in the

contractor's cost of, or the time required for, performance of any part of the work under this contract, then negotiations shall commence between owner and

contractor to provide equitable adjustment to owner or contractor resulting

therefrom.

5. These specifications shall consist of dearing and grubbing, preparation of land to

be filled, filling of the land, spreading, compaction and control of the fill, and

subsidiary work necessary to complete the grading of the filled areas to conform

with the lines, grades and slopes as shown on the accepted plans.

6. These specifications shall be integrated with the Soil Engineering Report of

which they are a part. Should conflicting statements be found between these

standard spedficatiQl'IS and the itemized recommendations contained in the main

body of the sod report, the latter shall govern.

7. The standard test used to define minimum densities of compaction work shall be

the ASTM Test Procedure D 1557. Densities shall be expressed as a relative

compaction in terms of the maximum density obtained in the laboratory by the

foregoing standard procedure.

!. Existing structures, foundations, trash, debris, loose fill, trees (not included in

landscaping), roots, tree remains and other rubbish shall be removed, piled or

burned or _otherwise disposed of so as to leave the areas that have been disturbed

with a neat and finished appearance free from debris, No burning shall be

permitted in the area to be filled.

';I.

10.

Existing septic tanks and other underground storage tanks must be removed from

the site prior to commencement of building, grading or fill operations.

Underground tanks, including connecting drain fields and other lines, must be

totally removed and the resulting depressions properly reconstructed and filled.

Depressions left from tree removal shall also be properly filled and compacted.

Abandoned water wells on the site shall be capped according to the requirements

of the appropriate regulatory agency. The strength of the cap shall be at least


11.

12.

13.

14.

1'.

3

eq1,1al to the adjacent soils. The final elevation of the top of the well casing

must be a minimum of th.irty-sb (36) inches below adjacent grade prior to grading or fill operations. Structure foundations should not be placed over the

capped well.

Organic matter shall be removed from the surface upon which the fill,

foundations or pavement sections are to be placed. The surface shall then be

plowed or scarified to a depth of at least eight (3) inches and until the surface is

free from ruts, hummocks or other uneven features which would tend to prevent

uniform compaction by the equipment to be used. Specific recommendations

pertaining to stripping and minimum depth of recompaction of native soils are

presented in the main body of the soil report.

Where fills are made on hillsides or exposed slope areas, greater than 10%,

horizontal benches shall be cut into firm undisturbed natural ground to provide a

horizontal base so that each layer is placed and compacted on a horizontal plane.

The initial bench at the toe of the fill shall be at least 10 feet in width on firm,

undistubed natural ground at the elevation of the toe stake placed at the natural

angle of repose or design slope. The width and frequency of succeeding benches

will vary with the soil conditions and the steepness of slope.

Native soil free from organic material and other deleterious material may be

used as compacted fill; however, during grading operations the soil engineer will

re-examine the native soils for organic content.

Imported material should be tested and reviewed by the soil engineer before

being brought to the site. The materials used shall be free from organic matter

and other deleterious material.

The selected fill material shall be placed in layers which, when compacted, shall

not exceed six (6) inches in thickness. layers shall be spread evenly and shall be

thoroughly blade-mixed during spreading.

16. When fill material includes rock, large rocks will not be allowed to nest and voids

must be carefully filled with small stones or earth and properly compacted.

I I I I I I I I I I I I I I I I I I ~

17.

IS.

19.

20.

21.

4

Rock larger than six (6) incites in diameter will not be permitted in the

compacted fill without review as to location by the soil engineer.

When the moisture content of the fill materiaJ is not sufficient to ac:hleve

required compaction, water shall be added until the soils attain a moisture

content so that thorough bonding is achieved during the compacting process.

When the moisture content of the fill material is excessive, the fill material

shall be aerated by blading or other satisfactory methods until the moisture

content is reduced to an acceptable content to achieve proper compaction.

After each layer has been placed, mixed and spread evenly, it shall be thoroughly

compacted to a relative compaction of not less than ninety percent (90%).

Compaction shall be by sheepsfoot rollers, vibrating sheepsfoot rollers, multiple

wheel pneumatic-tired rotlers or other types of acceptable compacting rollers.

Rollers shall be of such design that they will be able to compact the fill to the

specified density. Rolling shall be accomplished while the fill material is within

the specified moisture content range. Rolling of each layer shall be continuous

over its entire area and the roller shall make sufficient trips to insure that the

required density has been obtained.

Field density tests will be performed by the soil engineer during grading

operations. At least one (1) test shall be made for each five hundred 000) cubic

yards or fraction thereof placed with a minimum of two (2) tests per layer in

isolated areas. Where sheepsfoot rollers are used, the soil may be disturbed to a

depth of severaJ inches. Density tests shall be taken In compacted material

below the disturbed surface. When these tests indicate that the density of any

layer of fill or portion thereof is below the required density, the particular layer

or portion shall be reworked until the required density has been obtained.

The fill operation shall be continued in six (6) inch compacted layers, as specified

above, until the fill has been brought to the finished slopes and graded as shown

on t!-.: accepted plans.


22.

23.

24.

2,.

5

Earth·moving and working operations shall be controlled to prevent water from

running into excavated areas. Excess water shall be promptly remo\'ed and the site kept dry.

Fill material shall not be placed, spread OI' rolled during unfavorable weather

conditions. When the work is interrupted by heavy rain, fill operations shall not

be resumed until field tests by the soil engineer indicate that the moisture

content and density of the fill are as previously specified.

The methods for removal of subsurface irrigation and utility lines will depend on

the depth and location of the line. One of the following methods may be used:

I) Remove the pipe and compact the soil in the trench according to the

applicable portions of these grading recommendations, 2) The pipe shall be

crushed in the trench. The trench shall then be filled, compacted according to

the applicable portions of these grading specifications, J) Cap the ends of the

line with concrete to mitigate entrance of water. The length of the cap shall not

be less than five (') feet. The concrete mix shall have a minimum shrinkage.

Whenever the words "supervision", "inspection", or "control" appear they shall

mean periodic observation of the work and the taking of soil tests as deemed

necessary by the soil engineer for substantial compliance with plans,

specifications and design concepts.

'[50URCES AGfNCY G[ORCE D~U!i'.MFJIAN, ---······-·· Dr ... · 3/4/1985 · lies immediately south of Huntington Drive, but it would he helpful if future reports cont~ined

Documents