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HomeMy WebLinkAboutTract Map 3929 Lot 78 Preliminary Soils & Foundation I I I I I I I I I I I I I I I I I I I PRELIMINARY SOIL AND FOUNDATION INVESTIGATION REPORT LOT 78 OF TRACT 3929 A.P.N. 921-160-002 NORTHEASTERLY OF DEL REY ROAD AND AVENIDA VERDE CITY OF TEMECULA RIVERSIDE COUNTY. CALIFORNIA .EQL MR. GREG LA BONTE PROJECT NO. 02-045.PI DATED JANUARY 15. 2003 Lakeshore Engineering 4 I I I I I I I I I I I I I I I I I I . LAKESHORE Engineering Consulting Civil Engineers January 15, 2003 Project No: 02-045.PI Client: Mr. Greg La Bonte 30861 White Rocks Circle Temecula, CA. 92591-1540 (909) 204-4417 Subject: Preliminary Soils and Foundation Report Proposed Single Family Home Construction Lot 78 of Tract 3929 Northeasterly Corner of Del Rey Rd. and Ave. Verde Temecula, County of Riverside, CA. A.P.N. 921-160-002 INTRODUCTION This report presents our finding and conclusion of a preliminary soils and foundation investigation for the proposed construction of a single family home to be located at the subject property. The purpose of this preliminary site investigation was to a) determine and/or evaluate the subsurface soil conditions under the site and b) provide pertinent earthwork and foundation design recommendations for the construCtion of a single family home. This site investigation included the following scope of work: 1) Performed two exploratory backhoe trenches within the proposed building pad areas to determine subsurface soil conditions and also to recover representative soil samples for laboratory testing (Appendix A) . 2) Laboratory testing of a representative soil sample to determine the onsite soil properties (Appendix B) . 3) Engineering analyses for necessary earthwork preparation and foundation design. 4) And the preparation of this report. PROPOSED CONSTRUCTION A single family home is proposed for construction on the subject lot. It is a 1/2 acre sloping lot, with ground surface rising from west to east direction at about a 20 % uniform grade. The residence will be a combination one and two stories, L-shape in design with the garage and guest (granny) unit along the wing. Only the main house is planned for two-story section. House construction will be of an upper scale, customed design home, consisting of about 4,000+ square feet of covered living space. 31520-8 Railroad Canyon Road. Canyon Lake, CA 92587 . (909) 244-2913 . FAX: (909) 244-2987 \ I I I I I I I I I I I I I I I I I I I January 15, 2002 Project No. 02-045.PI Page Two Foundation is planned for conventional spread footings and concrete slab-on-grade floors, supporting woodframed stud walls with tile roofing. Review of precise grading plan for this lot indicated, a combination of retaining walls and cut/fill slopes are proposed for support of the building pad. Walls are in the order of 6 feet high and fill slopes are tentative planned at 12 feet or less, pitched at 2:1/H:V. Cut slopes are less than 5 feet high. BACKGROUND INFORMATION/SITE DESCRIPTION The subject lot is located on the easterly side of Freeway l5, in the community called Meadowview, approximately 3 miles northeast of old town Temecula. The Community of Meadowview consist of an older subdivision (+25 years) of estate size individual single family home lots. Lot size is about at least +1/2 acre. The community is over 60 percent built out, supporting custom designed, upper scale, single family homes. The property is a raised/berm corner lot, fronting Del Rey Road to the south and Avenida Verde to the west. Single family homes are to the north and east. It is about rectangular in shape, measuring 200 in length (east-west) by about 100 feet in width. Terrain in the area consist of undulating gentle sloping hills and valleys, with slopes pitched at about a 5:1 (H:V) or flatter. The subject property is a upslope lot, with the body of the lot raised (bermed) from the street. Cut slopes are along both streets right-of- way. The natural ground on the lot is sloping, and has an gentle 5:1/ H:V upward slope from west to east direction. Maximum relief is about 40 feet. The subject lot is undisturbed at the time of our site investigation. Groundcover consist of annual grass and scattered eucalyptus trees along the streets right-of-way. No rock outcrops and/or water wells were noted onsite or on adjacent properties. The surface contours in general are smooth and uniform with no erosion observed on the property. Drainage is by surface sheetflow from east to west, towards Avenida verde, paved road. Utilities are subsurface with proposed onsite septic system. SUBSURFACE CONDITIONS Two exploratory backhoe pits were conducted on the site to determine the subsurface soil profile. Based on our exploratory efforts, the site is mantle with a thin layer of topsoil (21/2 feet) underlain by Quaternary Pauba Sandstone/siltstone. Lakeshore Engineering '3 I I I I I I I I I I I I I I I I I I I January 15, 2002 Project No. 02-045.PI Page Three TOpsoil consist of a thin layer, approximately 24-30 inches of a medium brown, Silty SAND (SM) , loose and porous, roothairs with clay trace. The underlaying bedrock consist of pauba Sandstone and siltstone mix, yellow brown, slightly moist, dense, cemented with no voids. Water seepage and/or clays were no encountered in our exploratory trenches. Generally, clay exist in trace form only and the upper soils are considered LOW in expansion potential. GENERAL/SITE GEOLOGY AND SITE SEISMICITY For general and site geology, please refer to attached report in the appendix, prepared by Mr. John Rossi (engineering geologist) . The subject lot is not within any designated (county and/or state) special study (fault hazard) zone. It is located about 2 1/2 kilometers from the Elsinore-Wildomar fault line envelope. The 1997 Uniform Building Code has assigned the Elsinore fault as a Type "B" fault. The shallow bedrock underlying the property is considered a favorable attribute. Based on Uniform Building Code (UBC 1997 edition), the site is considered within 5 kilometers or less from the center of a known area of high regional seismicity (Map Figure 16-2) . As such, the following data based on known or assumed parameters as outlined in the tables under Section 16, Volume 11, '97 UBC, are presented below: Seismic Zone (UBC Figure 16-2) ----------------- Zone 4 Seismic Zone Factor "z" (UBC Table 16-I) ------- 0.40 Seismic Source Type (UBC Table 16-U) ----------- B Soil Profile Type (UBC Table 16-J) ------------- Sd Seismic Coefficient "Ca" (UBC Table 16-Q) nnn 0.44Na Seismic Coefficient "Cv" (UBC Table 16-R) ------ 0.64Nv Near Source Factor "Na" (UBC Table 16-S) ------- 1.1 (Interpolated) Near Source Factor "Nv" (UBC Table 16-T) ------- 1.2 (Interpolated) The above values are considered applicable to this study site and should be used in conjunction with applicable UBC design formulas. SECONDARY AFFECTS Secondary affects of earthquake activity, such as rock falls, landslides and/or flooding were given consideration. The possibility of any event occurring is considered very small/unlikely. Liquefaction does not appear likely because of the high ground elevation and shallow competent bedrock under this site. The site is free of loose surface boulders and hazard from rockfall is nil. Lakeshore Engineering A.. I I I I I I I I I I I I I I I I I I I January 15, 2002 Project No. 02-045.PI Page Four CONCLUSION AND RECOMMENDATIONS GENERAL From a soil and foundation engineering standpoint, the site will be suitable for the planned single family residential construction, provided conclusions and recommendations presented in this report are incorporated in the design considerations, project plans and job specifications. ROUGH GRADING AND EARTHWORK Based upon our review of grading plan already prepared for subject property (xerox reduction copy attached), it is our understanding that site rough grading will be required to provide the following: 1) a split level pad for support of construction; 2) suitable subgrade soil for support of building foundation; 3) adequate surface gradients for control of water runoff from manufactured pad; and 4) provide access space for construction equipments (to accommodate the installation of foundation and utility systems) . After the areas to be rough graded have been stripped and cleared of surface vegetation and tree stumps roots, the on-site soils will be considered satisfactory for reuse in the construction of engineered fills. Per review of grading plans prepared for the site, 2:1/H:V fill slope of approximately 12 feet high are proposed along the low westerly side of lot. Fill dirt will be derived from the higher easterly side of lot to be benched level (cut) at pad grade. Retaining walls in the order of 6 feet are proposed along the easterly rear property line and also along the westerly side and rear of the garage. All walls are planned for level backfills. Removal of loose and/or substandard topsoil is required prior to placing any engineered or structural fill dirt. Depth of loose soil removal will vary with specific location and is to be determined during the actual fill construction. However, based on our exploratory test pits conducted, overexcavation of 30 inches of existing topsoil is expected. Actual depths of overexcavation should be field determined and approved by geologist or engineer at the time of grading operations. The natural residuum (dense sandstone/siltstone) encountered below the existing topsoil layer is considered competent for support of new fill dirt for building pad construction. Lakeshore Engineering ~ I I I I I I I I I I I I I I I I I I I January 15, 2002 Project No. 02-045.PI Page Five All exposed bottom of grading excavation should first be scarified another 6 inches, moisture conditioned to near optimum and densified to at least 90 percent of the maximum laboratory dry density as determined by the A.S.T.M. D1557-78 compaction method. Boulders encountered during grading that are 6 inches in diameter or larger, should not be used in structural fills. Where overexcavation of building pad is determine to be required, the limits of rework should extend at least 4 feet beyond the building footprints. Any surface or subsurface obstructions encountered during grading such as rocks, utility/irrigation lines should be removed from any areas to receive fill. No underground obstructions nor facilities should remain in any structural areas which receive compacted fills, building foundations, concrete slabs and/or pavements. Depression and/or cavities (including exploratory trenches) created as a result of the grading obstruction removal, should be properly backfilled with suitable fill materials and compacted under engineering observation and testing. All fills should be densified in conformance with the appropriate grading code but shall be less than 90 percent relative compaction by mechanical means only. EXCAVATING AND RIPPABILITY Rework of on-site soils should not be difficult to accomplish with standard earthmoving equipment such as a D-6 or larger. The walls of temporary construction excavations should stand nearly vertical, provided the total depth does not exceed 5 feet and surficial stability is verified. Shoring of excavation walls or flattening may be required if greater excavation depths are necessary. For deeper cuts, slopes should not be made steeper than 1:1 (H:V). All work associated with trench shoring must conform to the State of California Safety Codes. Native organic free soils may be permitted provided both the backfill and the native materials have a minimum sand equivalent of 30 and the required relative compaction can be achieved. GRADING CONTROL All grading and earthwork including trench backfill should be performed under the observation and testing of the soils consultant or their representative. Sufficient notification prior to stripping and earthwork construction is essential in order that the work be adequately observed and tested. In order for us to provide a written opinion as to the adequacy of the soil compaction and trench backfill, the entire operation, most importantly at the time of trench backfill, should be performed under our observation and testing. Lakeshore Engineering (p I I I I I I I I I I I I I I I I I I I January 15, 2002 Project No. 02-045.PI Page Six PROPOSED SLOPES AND STABILITY Fill slopes are not proposed at this time. Fill slopes are proposed less than 15 feet high pitched at 2:1/H:V maximum. Slopes constructed under engineering inspection and testing should be stable and considered suitable for its intended use. New cut slopes are proposed at less than 6 feet, also to be pitched at no steeper than 2:1/H:V. Cut slopes made in puaba formation bedrock, should be considered grossly stable from deep seated bedrock failure. FOUNDATION DESIGN FOOTING The proposed single family home construction may be supported on conventional spread footings established in either competent native soil (Pauba bedrock Formation) or to be founded entirely on engineered (compacted) fills. These spread footings may be designed for an allowable bearing value of 1500 pounds per square foot. This design value may be increase by one third, if the Structural Engineer takes into consideration short duration structural loading conditions, such as induced by wind and/or seismic forces. All footings should be 18 inches deep (below lowest adjacent grade) and 12 inches in width. All continuous foundations should be reinforced with at least two no. 5 rebars, one at near the top and one rebar at near bottom and consistent with the recommendations of the Structural Engineer or Architect and the guidelines in the U.B.C. SETTLEMENT Total settlement due to maximum allowable structural loads of l500 pounds per square feet pressure should not be a factor as they should be less than 1/2 inch. Differential settlement should be within tolerable limits (estimated at less than 1/3 inch). LATERAL CAPACITY For design, resistance to lateral loads can be assumed to be provided by friction acting at the based of the foundations and by passive earth pressure and may be combine without reduction. If passive earth pressure is used, it is important that backfill should be placed under engineering observation and testing. Lakeshore Engineering 1 I I I I I I I I I I I I I I I I I I I January 15, 2002 Project No. 02-045.PI Page Seven A coefficient of friction of 0.30 may be used with the dead load forces. An allowable lateral passive earth pressure of 200 pounds per square foot per foot of depth may be used for the sides of footings poured against undisturbed and/or recompacted soils. The lateral bearing values indicated above are for the total of dead and frequently applied live loads. If the normal code requirements are used for seismic design, the values may be increased by 1/3 for short durations of the loading which include the effect of wind or seismic forces. RETAINING WALLS Per review of grading plan, proposed free standing retaining walls are limited to 6-7 feet supporting level backfills. All retaining wall footing excavations should be inspected by a geologist or engineer to assess whether the subgrade conditions are competent and as anticipated. In the event adverse geological conditions are encountered, appropriate recommendations in the wall structure will be presented. However, for preliminary design, the following guidelines are presented: 1. Where a free standing structure is proposed, a minimum equivalent fluid pressure, for lateral soil loads, of 35 pound per foot may be used for design, provided the backfill is of LOW expansive soils and level backfill. Sloping backfill is not anticipated for this site. If the wall is restrained against free movement (1% of wall height) then the wall should be designed for lateral soil loads approaching the at rest condition. Thus, for restrained conditions, the above value should be increased by 20 pounds per cubic foot for non-expansive granular backfill. In addition, all retaining structures should include the appropriate allowances for any anticipated surcharge loads. 2. An allowable soil bearing pressure of 1500 lbs. per square foot may be used in design for footings imbedded a minimum of 18 inches below the lowest adjacent grade. 3. A friction coefficient of 0.30 between concrete and natural or compacted soil and a passive bearing value of 200 lbs. per square foot per foot of depth may be employed to resist lateral loads. 4. A uniformly distributed horizontal load equal to one-half the vertical surcharge load should be applied to a wall whenever a surcharge is within a horizontal distance of one-wall height. Lakeshore Engineering <0 I I I I I I I I I I I I I I I I I I I January 15, 2002 Project No. 02-045.PI Page Eight 5. All design pressures assume that sufficient drainage will be provided behind the walls to prevent the build-up of hydrostatic pressures from surface water infiltration. Adequate drainage may be provided by means of a system of subdrains and/or weep holes with filter material installed behind the walls. The filter material should extend a minimum of 24" horizontally from the back of the wall. 6. Care should be taken when compacting the walls, such that excessive lateral loads are not produced by compacting equipment. CONCRETE SLAB-ON-GRADE FLOORS The onsite native and stockpile soils are granular in nature and considered to be low in expansion potential. Expansive soil potential should be again reviewed at completion of rough grading operation. Concrete floor slabs may be supported directly on properly prepared subgrade. presaturation of subgrade is not mandatory. If a floor covering that could be critically affected by moisture, such as vinyl tile, slabs should be protected by a plastic vapor barrier of six-mil thickness. The sheet should be covered by at least two-inches of sand cushion to prevent punctures and aid in concrete cure. The concrete floor slabs should be reinforced with at least 6" x 6"-#6/#6 welded wire mesh or equivalent bar reinforcing (no. 3 rebars at 18 inches on center) and installed at mid-height (using chair support). Concrete floor slabs should be at least 4 inches thick nominal. Expansion joint should be kept at 14 feet or less apart in both directions. SITE DRAINAGE Positive drainage should be provided around the perimeter of all structures to minimize water infiltrating into the underlying soils. Finish subgrade adjacent to exterior footings should be sloped down and away to facilitate surface drainage. All drainage should be directed to natural flowline/watercourse via non-erosive devices (swales and ditches) . The homeowner should be made aware of the potential problems which may develop when drainage is altered through construction of retaining walls, patios and pools. Ponding water situation, leaking irrigation systems, overwatering or other conditions which could lead to ground saturation must be avoided. Lakeshore Engineering C\. I I I I I I I I I I I I I I I I I I I January 15, 2002 Project No. 02-045.PI Page Nine FOOTING TRENCH EXCAVATION INSPECTION All footing excavations should be inspected and approved by the Soils Consultant prior to placement of footing forms, reinforcement, or concrete. Materials generated from excavations should not be spread on slab-on-grade areas, provided they are compacted and tested. GENERAL INFORMATION AND LIMITATIONS 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 trenches. In view of the general conditions of the area, the possibility of different local soil conditions cannot be discounted. It is the responsibility of the owner to bring any deviations or unexpected conditions observed during construction to the attention of the consulting engineer. In this way, any required supplemental recommendations can be made with a minimum of delay to the project. Prior to initiation of grading, a meeting should be arranged by the developer and should be attended by representatives of the governmental agencies, contractors, consultants and the developer. Construction should be inspected at the following stages. o Upon completion of demolition and clearing. o During all rough grading operations including removal of unstable materials, precompaction and filling. o During trench backfilling but prior to paving or other construction over backfill. The findings and recommendations of this report were prepared in accordance with generally accepted professional principles and practice in the field of geotechnical engineering. This warranty is in lieu of all other warranties, either express or implied. to be of service. If you have at your convenience. JOHN ROSSI Lakeshore Engineering \0 I I I I I I I I I I I I I I I I I I I APPENDIX ll. FIELD EXPLORATION Field exploration was performed on the afternoon of November 19, 2002 using a backhoe (Diamond Backhoe Services). The soils were continuously logged by our field personnel and classified by visual examination in accordance with the Unified Soil Classification System. Our trench logs are attached for review. To evaluate the compaction characteristics of the fill material, field density tests were performed. Also, representative bulk samples were recovered and shipped to the laboratory in polythelene bags for laboratory testing. Mr. Greg La Bonte Lot 78 of Tract 3929 N.E.C. Avenida Verde & Del Rey Rd. Meadowview, Temecula, CA. Project No. 02-045.PI Report Date January 15, 2003 Lakeshore Engineering \\ I I I I I I I I I I I . ---1~ 0: -0' DO Cl~ ~n NO D= -o~ :1:; >-<~ n~ 3:' J>~ ""'D~ . -fl \ I lUH ~lil' ; t if (~ IiI! I hi 1 .111 1ft I {I .1' jIi }I. "I.; [] ~. \ "'2.\ I I . I I I ! ! B ~ \ ~> I I . I i . . ~a.~;1"~ i~ ,. , " . . , . x ~~.LIlo~.J : . . . l , . \ ~/' ~\ \ "- .~ t " \ .,;<. !I. i"1~ . ~ I l'z ll~ 1I~ ., G) m o -i m () :I: Z (1 )> r s: )> "tI < . , . !II it i~ li!~ "t ~II I! ~i f \1~1 ilil ~II I I NORT" E ~ "ll ~ I I I I I I I I I I I I I I I I I I I NUV-~O-~~ MON. L~;~7 ~ONATHAN L. RpS~I . ~.e2 . . . ... tley~p^CIFIC CONSUL rANTS, INC: ENGINe ~ & ENVIRONMENTAL GEOLOGIST .. _N, BoX'17VOj PAHRUMP, NEVADA 89041 ' . p.oaJOI;fI1, P~TTOH;CA.t23e9 I __ .' . '.',-' FIELD MEMO, J - TO: IA~"';;"_ ~u!J6~Aa'Jl":..- Ill' I .,...,..-. . ...'.. 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'. .l\o.t: ., '~'"\,::~ ~'...~::. . , . . :'. ., >-" ., - ..' ......~..":::::;..... .~Wf~. .. l{:;l~~~...\,.... ~ ""rXfJ}..~::....s~~~ew).. ~. ..~tHt'.... ... ".~'ll . . ....;..::... . .. ~ .... .;...,--., ;~._' . .~... .... .... r2~9I'AJN ..!l. ... .~.'. I l4NT$.INC; . ~rJ/fI. /~~~ . ~J~ ;. \'? I I I I I I I I I I I I I I I I I I I APPENDIX B LABORATORY TESTING EXPANSION INDEX TEST A representative soil sample was collected in the field and tested in the laboratory in accordance with the A.S.C.E. Expansion Index Test Method as specified by U.B.C. The degree of expansion potential was evaluated from measured soil volume changes obtained during soil moisture alterations. The results of the test are presented below: Trench Depth Soil Expansion Expansion No. (Ft. ) Description Index Potential ------ ----- ----------- --------- --------- T-1 0-2 Silty SAND < 20 LOW (SM/SP) DIRECT SHEAR TEST Direct shear tests were made with a direct shear machine at a constant rate of strain. The machine is designed to test the soil sample without completely removing the samples from the brass rings. Samples were tested to evaluate the internal angler of friction and cohesion. The test results (see attached sheet) are shown in terms of the Coulomb Shear strength parameters. Mr. Greg La Bonte Lot 78 of Tract 3929 N.E.C. Avenida Verde & Del Rey Rd. Meadowview, Temecula, CA. project No. 02-045.PI Report Date January 15, 2003 \~ Lakeshore Engineering ,_.._~u___ ,. __"~:..-"",.'..;.;.~:_:-'__" 'U~'. 1,';/ 1 1 I I I I I I ~ 2.0. c Ql L ~ I I I I 1 I I .J I Key: o Test. ot fiekl,mOilt~. content, . I · Tilts at .citurat.d molstur. cont.nt, " , LAKESHO'REr 'n, Engineering Date \)'E.L. _\Co.1.Jtt,L . Job bQ.Et; LA. ~iE...". x. MlE.\ffi'QJ)E( ~~((Q,w.b.'~ '.,--,"" SH~ARTEST DIAGRAM 3.5 J f.e .\ .' I I .1... I 3.0 2.5 r I I .. - ."" I I ,.. - - I ,. u. en ~ .' 2J'o'\.\ U)JQlSTIA . - T-~ e.4' , S;AI,d ,~ 1.5 ... 2 .&: en 1.0 I " . ., .... - -c.:t lllo ~ . 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LOT 18 01' DACT 3929 stJIlDIVIIIIOIJ 0Ii' POaTIOIJ 01' RAlfOIO 'I'IIMBCULIl 1iI.I.C. D8L RBY JUl. . AVI. VKRDB L2..Ji.. 921-1632-002 crn- 01' 'I'IDIIlCUI-'. CA. ~RllPAilli:D lIY: LAXBSHOR2 81i1GINi:ERING 31520-B RAILROAD CAIiI'lON ROAD CANTON LAItB, CA 92581 - - --ncrHCATBS DISTING ~ wtQW ~ nmICA~ PROPOSBD PnoSIIBD 0':INI'00R Lnar -..,.. _. Il!IDlCATBS DIRBCTIOIJ OP FLOW CSWALBS) PIIOPOSICO arl8: OZ'SSO:iCUIIIC YARDS PROPOSBD PILLS: TCOBIC YARDS l'aOP08K1l BllPDll'T: COBIC YI.JlDS PIIOPOSIlO IMPORT: COBIC 'tlI.RDS NOTB: YAiWAalI PROVID8D AlU! Rou:;Jl BN3Il., BST. FOR l'LAN Cll:. nSS DllTBRMlNATIOI.I BY CITY <>nor......" no' .......on HOTB: RBrJ,DlDIG DoLLS PRDPOSBD CII THIS lIUUI IS SUBJBCT TO SBPUATJI PLAIiI amca AIID _ITS 1UIQOl~. '0. '0 <2.lAl.E.l""Zo(\>l.') '....lO'L"':). " ReVISIONS DATE olICC'Il BENCH HARK "r.LP.c..NJu'Il~f'Q.h; .'2LE.u.lWlCO<<lI!.I"~. m:- frl&.bA\IOltE..bE.L'RE'l~. ~". R.fI.\\."'" t:,eAt..00I6: <L.n:: NE>>OA ~,Ao;..NlO'o!l"1'Crw~ SEAL, DIslgnl'c<By Dr".n By SCALE Clwck"d By --. P\"flS P""po.,."c< UndE,. Sup""vlSlOn Of -- \""LO' v..._., DCl1o~ ,loz..olo~ ~- Ih"'2.'t~. RoC.E. No. .....1u.u.>t.-. bpr.. t.l....ol~4 B.<M-T1O.TIm ~.. nn:a.""'TT1t<l ~----u--- IlCDlCA'l'BS "I1tANSITIOIIAL COT/PILL LDnI .l:I..LIW:.;. MR. GRBG LA BONTa 30861 IlHITB ROCKS crRCLB TDmCOLA, CA_ 512591 154D (51D9) 204-4417/587__8713 RECOHHENDEDBY, DATE' CITY OF TEMECULA DE:PARTKE:NT or PUBLIC. IJORKS f)r-o..1ng No. ACCEPTED BY. DATE. PR1Nl:IP""--DlGlHEDtrDRCITY~lIla:R . N PLAN LOT 78 TR. 3929 .E.C. DEL REY RD. & AVE. VERDE Sh..t I of I .=- u~. 02..-OA'!:::'P. ,~ I I I I I I I I I I I I I I I I I I I A.PPENDIX C GENERAl/SITE GEOLOGY REPORT BY MR_ JOHN ROSSI Lakeshore Engineering \'\ I I I I I I I I I I I I I I I I I I I ENGINEERING & ENVIRONMENTAL GEOLOGIST MSC 210, BOX 1790, PARUMP, NV. 89041 TO: Lakeshore Engineering 31520 Railroad Canyon Rd, #B Canyon Lakes, Ca, 92587 SUBJECT: REPORT - Geologic & Seismic Conditions at the Site of Proposed Residential Structure, Le Bonte Property, Lot 78, Tract 3929, Located on the Northeast Comer of Avenida Verde & Del Rey Road, Meadowview, City of Temecula, Riverside Co" CA (NW1/4, SE1/4, NW1/4, See 30, T7S, R2W, SBB&M), ATTENTION: Mr. & Mrs. Le Bonte - Property Owners, Client Fen Yong, RCE - Principal, Lakeshore Engineering 1 0 INTRonIlCTION- We are pleased to present this letter report of findings for the existing geologic and seismic conditions at the proposed residential development located on the northeast comer of Avenida Verde & Del Rey Road, North Temecula/Rancho California area, City of Temecula, Riverside County, California, The proposed site consists of an undeveloped natural hillside lot facing west, with access from Avenida Verde. This paved residential road connects with Del Rey Road, which leads to Solona Way the south, and Margarita Road. Our scope of work is limited to providing a description of the geologic conditions present at the subject site including general geology, faulting and seismicity, groundwater description, and presentation in this letter report. Seismic conditions were evaluated based on published earthquake and seismic information, and 97UBC. Our work does not address or consider any aspects of a Phase I Site Assessment for Hazardous Materials or Asbestos containing building materials, and is not a soils & foundation investigation, This letter report presents our findings, conclusions, and recommendations concerning the existing geologic and earthquake/seismic conditions present at the subject site, It is provided for the soils engineer, his use in the geotechnical report, and to the client. ? n SITF nFSCRIPTION _ The subject site is located on the east side of Avenida Verde, and on north side of Del Rey Road, in the older, secluded Meadowview development area, north Temecula, Riverside County, California, The property is roughly rectangular, covering approximately .76 acre. A small cut slope is present on the south side of the site (Del Rey Rd.), and on the west side of the site (Avenida Verde). The site is a shallow hillside sloping to the west, toward Avenida Verde. Ground cover consists of native weeds & grasses. A few large Eucalyptus trees are present along Del Rey Road, and a few scattered landscape trees are present on the site, The property is bordered on the north and east by existing residential housing, Two backhoe exploration trenches were excavated in the central portion of the site. There were no springs, seeps, or water wells observed at or near the subject site. Underground utilities are present in both paved streets,(see Figure 1, Index Map), \f6 I I I I I I I I 1 I I I I I I I I I I -2- Lakeshore Engineering Project No. 02-45PI NPC IN: 0020019,01 January 20, 2003 30 !;IIMMARV nf FINnING!; _ ~ 1 GAnlngit! ~Atting _ The subject site is situated within the central portion of an elevated older alluvial plain forming the pediment surface of rolling foothills northeast Temecula Valley and north of the Pauba Valley. The older alluvium consists primarily of a massive, partially cemented, well-indurated Pleistocene sandstone (Pauba Formation-Sandstone unit) exposed across most of the region, The Pauba Formation contains a massive to poorly bedded, reddish brown, coarse to graded sandstone unit, in places containing thin (6" to 12") interbeds of grey green to grey brown micaceous siltstone. Siltstone can be predominant in the region, with minor sandstone. Narrow, thin stream channel deposits of Holocene alluvium are present within the shallow canyons developed within the pediment surface. Older, well-developed stream and river channels typically contain thick unconsolidated silt rich sandy alluvium. The pediment surface is bordered on the north and east by intrusive granitic and older marine metasediments of Bachelor Mtn. and Black Hills. Traces of the Agua Caliente Fault zone are mapped (CDMG Santa Ana Sheet-1965) at the contact of the Pauba sandstone with these hard rock units, The TemeculalElsinore Graben is bordered by the Wildomar Fault on the northeast, and the Willard Fault on the southwest. Both of these fault segments are considered part of greater Whittier/Elsinore Fault Zone. The Pauba sandstone pediment surface is located within the boundaries of the Perris structural block. The Perris Block is a northwest-southeast trending structural block bordered on the northeast by the San Jacinto Fault, on the southwest by the Whittier/Elsinore Fault System (Wildomar Fault), on the northwest by the Chino Basin, and on the southeast by the Agua Calenti fault Zone and Borrego Valley. Similarly, the Santa Ana Mountains Block is bordered on the northeast by the Whittier/Elsinore Fault Zone, on the southwest by the offshore Newportllnglewood - Rose Canyon Fault System, on the northwest by the Orange Coastal Basin, and on the southeast by older cross faults in the San Diego _ Baja California area. The closest active or potentially active faults capable of affecting the subject site (if an earthquake event were to occur on one of these faults near the site) are the Wildomar Fault approximately 2.8 miles to the southwest, and the San Jacinto Fault approximately 20.0 miles to the northeast. Both of these faults are considered active, and are Earthquake Fault Zones. The recently zoned Wolf Valley fault located some 4.0 miles to the south, on the southwest side of the Temecula Graben, is considered a portion of the Elsinore Fault Zone, and possibly an extension of the Willard Fault identified further to the northeast on the southwest side of the Temecula Valley. No active or potentially active faults were observed on the subject property, or were present on the site in the literature reviewed. The site is not included within the Wildomar Fault Earthquake Fault Zone, Older east-west trending fault traces (Murrieta Fault) are reported on M.P, Kennedy's Map (CDMG Sp.Rpt. 131, Plate 1) 2.0 miles to the north of the site, and two very short north-south fault segments located 1/2 mile to west of the site at the original MWD San Diego Aqueduct. These faults are not Earthquake Fault Zones, and are not well defined in the literature, 1J; I I I I I I I I I I I I I I I I I I I -3- Lakeshore Engineering Project No, 02-45PI NPC IN: 0020019.01 January 20, 2003 ~ 2 On_C:;it,. ~Anlngy _ F::llrth M::llhui:ll~ _ ~ 2 1 Tnp~nil~- A thin layer (12":t) of poorly developed topsoil is usually present over native subsoils and bedrock. Topsoils in the area consist of loose, brown to yellow brown, porous, well-graded silty sands and clayey sands where shallow bedrock is present (Pauba Fm. sandstone), 3 " R..tlrnck (Op....) - Bedrock exposed on or near the site, and underlying the property consists of the Quatemary Pauba Formation Sandstone, a regionally distributed poorly cemented (CaC03 & salts), friable well graded sandstone with limited poorly defined bedding, and containing interbeds of grey to brown siltstone, The Pauba is a young continental deposit containing a large number of sedimentary depositional structures: coarse channel fills, cross-bedding and graded bedding, and alluvial fan structures. Pauba sandstone at the subject site consists of reddish brown-to- brown well-graded sandstone with a moderately high silt and clay content. In addition to salt cementation clay acts to bind the sand grains of the arkosic sediment into a poorly consolidated continental sandstone. Excavation is relatively easy with standard backhoe, and the Pauba stands up well in cut slopes up to 30 feet. However, the Pauba is easily eroded, and can be cut with water where run-off is not controlled. Erosion gullying and animal burrowing in the slope face is considered a problem with existing slopes in the area. Bedrock is exposed at the surface in the existing cut slope and cut pad. Pauba sandstone is known to be underlain by Temecula Arkose in the region.(see Figure 4, Geotechnical Map - reduction)(see Figure 5, Geologic Cross- section A-A' - reduction). :1:1 (.;jrnllndw:lhu.. Groundwater is present throughout the region as an unconfined alluvial aquifer within the Younger and Older Alluvium underlying the site, and in the underlying Pauba sandstone. The bedrock is considered as moderately good water bearing aquifer, and can yield limited amounts of groundwater to domestic water wells from primary and secondary porosity, Regional groundwater within the graben basin occurs over a thick section of several hundred feet, and is utilized by numerous domestic, municipal, and irrigation water wells. Localized perched groundwater may be present at the site and typically occurs at the base of the weathered bedrock zone. Perched groundwater is the result of local winter season percolating surface waters collecting over low permeability silt layers within the upper weathered Pauba sandstone. No springs or seeps were reported on the subject site. Additional information conceming the on- site hydrogeologic conditions may be obtained, if required, through the review of available water well drillers logs, and by additional on-site hydrogeologic investigation under separate study at the request of the client. z,.'7 r I --1, I AJ~ ~ ~ I I ~ f~ \ [] t ~I~"l ~ ~ 'II!, ! ~~Hl' . ~ '~"l 8 ~ -;-~- . i: ,~" a ~ ~~" i l lId ~ i ih ! ~ f. ;1 ~Il i fij I Ih' " '"'E I m. I I 1 I -. \ -> I I , i ~ I i ~ . ;:!!if "'!j ~,!~ !. ~ ('J\'llll'lJi! ~..8p'i~1!) ".".~ r( ~/ I - --;~/!il'. ~.~ t; !e:! g:!:t' <> Fw L ' \ K \ > k----r. ..,,~ ~. J: ffi _~ "\ ~O' ~~---- 11 \- \ ~K11 ~~t; \ .:I~.'~. 0'0 "'" "C x ~\t-~ VL . S G") Ill!: · m ;! !! 0 "! iJ -I !:~ ~ili.. m ~S!('j '13 (') iI~ S;='i::t ug i~;g!: ~~~ f'~ (') 'IF ~;')> Ii> il" r- ".z U ~ ~ ~ !" -i o m I 1 NORTH n ~ " ~ ~ ,.. ~ ~ '::: " ;;; .... 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"'to E glil : ~~ ~ I I I I I I I I I I I I I I I I I 1 I -4- Lakeshore Engineering Project No, 02-45PI NPC IN: 0020019.01 January 20, 2003 ~ 4 F::udting It ~~i~mi~ity _ ~ 4 1 F::udting- F::'lIilting - No surficial or other evidence of active or potentially active faulting was observed at the subject site during our field investigation, The subject site is not included in any Earthquake Study Zone for fault hazard, The Wildomar Fault Zone located approximately 2,8 miles to the southwest, and the San Jacinto Fault Zone located approximately 20,0 miles to the northeast are the closest Special Study Zone faults to the site. The Wildomar Fault Zone is considered to be a high angle and strike slip fault, strongly developed and clearly visible from aerial photographs, The San Jacinto Fault Zone extends along the foothills of the San Timoteo Badlands, and at the base of the south San Jacinto Mountains. The fault zone is considered to be a complex zone of high angle normal and strike slip faults with multiple and discontinuous fault strands as wide as 2 to 3 miles (San Jacinto & Casa Loma Faults San Jacinto Graben Valley). There are several other faults within the greater Southern California area, which could affect the site in terms of ground shaking in the event of an earthquake (see Figure 1, Index Map _ State EQ Fault Zone Map), Magnitllde - The Maximum Credible Earthquake is defined as the largest earthquake that appears to be reasonably capable of occurring under the conditions of presently known 'geologic framework' (CDMG OF Rpt. 92-1). The maximum probable earthquake considers the same criteria as the maximum credible, however, the historic record and recurrence interval for the given fault is also considered. This results in a statistical probability consideration being applied to the determination of the largest earthquake most probable to occur on the given fault. 'The maximum probable earthquake is the maximum earthquake that is likely to occur during a 100 year interval.'(CDMG Note 43). This has also been termed the Functional Basis Earthquake. Until recently earthquakes were measured utilizing the Modified Mercalli Intensity Scale, the Rossi-Forelli Intensity Scale, and the Richter Magnitude Scale. Within the past two to three years earthquake intensity has been scaled utilizing the Moment Magnitude Scale. 'Moment Magnitude is the measure of total energy released by an earthquake. Moment magnitude is the measurement and term generally preferred by scientists and seismologists to the Richter scale because moment magnitude is more precise. Moment Magnitude is not based on instrumental recordings of a quake, but on the area of the fault that ruptured in the quake. This means that the moment magnitude describes something physical about an earthquake. Moment Magnitude is calculated in part by multiplying the area of the fault's rupture surface by the distance the earth moves along the fault, The Moment Magnitude scale now supercedes the Richter scale. Cnmpari~nn hAtwAAn thE! Rir.htAr and MnmAnt MagnihJdA Sr.:IlIAS (UALR-ACEETT) Earthauake Richter Scale Mament Maanitude New Madrid MO 1812 8,7 8.1 San Francisco CA 1906 8,3 7,7 Prince William AK 1964 8.4 9,2 NorthridQe CA 1994 6,4 6.7 Moment magnitude values for causitive faults have been calculated by the CDMG, and where available are provided in Tables I and II below, (see Appendix A) 1fp . ~! ) \\ ~ ,1, ~/;f; _1, " / ,;? . y ,... ,) ..' 8 f ' ~::l' 'iJ' ,. OJ (f! ,~~!~1~! ~b /'1,' ,/ ] "1 t' ~ I '. \" ~ I , I~' \ :. V' I.. ' :t:-' ; .'- '1. ~ \,.<\i Ii - -' . ',,' ~~' /,' ".\~ ' , l . \ \ ~ ~.I . . ,-'-. ",'(\:.:) <.") ~~ ~.'!' \OU' Ii " . .', 01..i:! ~. ,- , ' ."j' g .""1 · ' --=-,,"- ~ '\ ,\ ~ i \ ~ 'l?'.. :';'': ~,~ "~~ /, ~'i>;,-:-' --= \' _\ " '\ ' ~ ~ X,~ f)~ F .. 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P' '.... ;:-/>:0/ (+ y~ , ,./ /. /" 0 \ t. />:;--';:>,1 , , ,7 \ ~I ,:'./'.; : \ a)~ ...... ,,/,/i" ' ~~,...,..:,:"i4 ......."~../../ / ~ "",A;~> '; /'.- - ~ ~ I I I I I 1 I ~ ..: - j' .' ------7-' ."'" , ,;.,' ...,?f'.tP~ rI ~ , ..---" 0 Z / _'~'" i~ #,0 "~ , <~ 00; /'" < o lEI Z .~ ~.A U ~.; ~ iU_ "._....,-~ /.-:...." ,/ ,-'; " ~ a < ~ l' ~ \ , " \ \ , <;:.....r,. ,..ff!." ~ :'I,l/ ~ .'. II I ~[!'. ,f ,I' ~!! . 1/ _'t'O ~ 1:1 'r., , \ \ Ir- s:! fT< Z " f J ! l I ! ~ l i i ! 1 , i "...1 / If If a II ;f " "I t j 1 l i , / / / '" 0 It~ ..a !:;;: ~::: f . , i 1 f i , 1 ~ I o i .. t , 1 f . , I ~ . i / ;/ ! .. .... - ~Hd Ii ~ III Iii t~ !~ illl 1. i' h .. J ' " II.. j!' ~q.ll e IU II !' I' ;t f! II 1- , I ...1, \.1 . - - . i . W. fi if .S' l;. tl j.1 {' j- ill J} II i!if H ~b ,I H hf -I ~i ~i')i I Ii . r r ~'I{ . i '. I r,t ~ of . if !~ " ' .II r 1~ t . . . ~ Z 'll o c.. ;;!: o o .... o o .... '" '" .... I I I I I I I I I I I I " " ~ ~ m 3:" 5 l>(") (") G)m u>l> ZZ 0-1 -1;:;1 cO c:;o -IZ Ou> :I: ITI mO o :;0...... p>......l>Z3: omz(")l> ol>Ol>c.. :;o~ rO G):I: ......:;0 :;00 0"T1 mC :;0)> l>!~ ZC ~m l>!:i ;ou> u> o - "Tl Z o o < ~ .. ~t .21 ~ . . ~ . .. ( . . -L~ + '. . < ~ o ~ ~ < .' , /, ./ I I' - /d I o o < ~ I I . /' ! " d /,' <v:j'/ .,'4' , /~ j// //,,/ .- -' r III ^ CD Ul ::T o CD m ::J c.o 5' CD CD ~ 5' c.o 'U ~ o '" , o .I> '" :!1 / ~ + ,/ - .0- ~, ' =, .' \f i.': I \ . /' jI !?: ..... 90 -I ~ w ~ Z m g> 3 CD ~ ~ ::3 a: ll> Cif a CD QO l? if '< el ll> .?- ;ol 3 CD g !" ~ ai Ul a: CD P' (") )> ::a m (i) o z )> r- "TI )> c: r- -I 1lO CJl m Cii 3: o ~ 3: )> "tJ I "T1 (i) C ::a m en 1 I I I I I I I I I I I I I I I I I I -5- Lakeshore Engineering Project No, 02-45PI NPC IN: 0020019,01 January 20, 2003 TABLE I CAPABLE EARTHQUAKE FAULTS MOMENT MAGNETUITE CDMG OF 96~8 RICHTER MAGNITUDE : ""_1 CAPABLE FAULT APPROXIMATE MAXIMUM CREDIBLE$ MOMENT MAGNITUDE% DISTANCE EARTHOUAKE Elsinore Fault@ 2,0+ miles 13.2+km\ SW 7.5M 6,8M Murrieta Hot SprinQs Fault . 2.4:l:miles (3,9:l:kml NE 6,OM " None Available Faults So. of Pauba Vallev'" 7,2+miles 111,6+km\SE 5,5M " None Available San Jacinto Fault 18,8+ miles 130,3+km\ NE 7,5M 6,9M Bannino Fault 31,0+ miles 150,2+km\ NE 7,5M None Available San Andreas Fault" 37,2+ miles 159,9+km\ NE 8.0 M 7,3M NewnorVlnnlewood Fault 48,0+ miles 177.3+krTl\ W 7,OM 6.9 M. Cucamonoa Fault 51,0+ miles 182,O+krTl\ NW 7,5M 6,8M $ - Richter Magnttude from CDMG OF 92-1 % - Moment Magnttude from CDMG OF-96-08 @ - Elsinore Fautt Zone - Glen Ivy Segment . - County Fautt Zone; -Suspected value, not published & . San Andreas Fautt Zone - San Andreas South Branch - San Bernardino Segment # - County Faults South of Pauba Valley 3 .4 2 SAi!C:mi~i~- Based on information provided by CDMG Map Sheet 23 - Greensfelder; CDMG OF 92-1, 'Peak Accelerations from Maximum Credible Earthquakes in California - Caltrans 1992'; and Seed & Idriss . Ground Motion and Soil Liquefaction During Earthquakes '(Earthquake Engineering Research Institute) the following conditions were determined for ground accelerations at the site for specific earthquake events at or near the subject site. Review of CDMG Map Sheet 54, which is presented in CDMG OF-92- 1 as a peak ground acceleration contour map includes the area of the subject site within the .6 9 acceleration contour, one of the highest ground accelerations for southern California. Moment magnitude values for specific faults were obtained from CDMG OF-96-08, Maximum credible earthquake magnitudes listed in CDMG OF-92-1 and associated bedrock accelerations are presented in TABLE II below. The subject site should perform during ground shaking as a soft bedrock or stiff soil site because of the at-site proximity of sandstone bedrock. Repeatable ground accelerations and ground surface deformation will occur to a greater extent in alluvium than at a bedrock site, The Pauba sandstone can be considered stiff alluvial soil or soft bedrock. (see Figure 6, Regional Fault & Seismicity Map), 1Jb I 1 I I I I I I I I I I 'I I I I I I I -6- Lakeshore Engineering Project No, 02-45PI NPC IN: 0020019,01 January 20, 2003 TABLE 1/ MOMENT MAGNITUDE MAXIMUM CREDIBLE EARTHQUAKE PEAK GROUND ACCELERATIONS LTS CAPABLE FAULT DISTANCE MOMENT MAXIMUM PEAK MAGNITUDE% CREDIBLEs ACCELERATION Elsinore Fault 2,0+ miles SW 6,8M 7,5M ,730 a Murrieta Hot SPrillilS 2,4+ miles NE None Available 6,OM ,5600 County Faults' 7,2+ miles SE None Available 5,5M . ,230_Q San Jacinto Fault 18.8+ miles NE 6,9M 7,5M ,295_Q BanniQQ Fault 31,0+ miles NE None Available 7,5M . 175-.J1. San Andreas Fault 37,2+ miles NE 7,3M 8.0 M . 185-.Jl Newoortllnalewood 48,0+ miles WSW 6,9M 7,OM ,075-.Jl CucamoQ.Qa Fault 51,0+ miles NW 7.0M 7,5M ,125-.Jl $ . Richter Magn~ude from CDMG OF 92-1 % - Moment Magnitude from CDMG OF-9EHl8 . - Suspected value, not published These ground acceleration values are for bedrock accelerations, and can be applied for any seismic condition stability evaluation of the subject site. Earthquake design criteria presented in the current Uniform Building Code, or in the County of Riverside Building Code Seismic Design Section, or design provided by the structural engineer and soils engineer in accordance with these requirements, whichever takes precedence, should be applied to the proposed development. Other active or potentially active faults in the region will probably produce less sever effects on the site as a result of an earthquake event, and considering fault to site distances will probably have a less sever to negligible effect on the site. (see Table II above), :\ 4:\ !=;;Ar.:nnl'f::lQf !=;Ai~mir.: 1-4::17::1rrht _ The potential for secondary seismic effects such as liquefaction due to the presence of granular sediments, shallow groundwater, and nearby active faulting capable of generating large earthquake events should be evaluated by the soils engineer, Based on our geologic observations at the site, and knowledge of the geology of the area, we do not consider the subject site to be a high risk for liquefaction due to the presence of the underlying cemented/clay bearing Pauba sandstone and lack of thick, granular alluvial sediments. Other secondary seismic effects such as differential settlement/compaction, ground surface rupture due to fault movement, or ground surface rupture due to lurching is not considered likely, but cannot be ruled out due to the faulted nature of the region, and the close proximity of active faulting which has produced ground surface rupture in the past. Seismically induced landsliding is not common in the Pauba sandstone, and is considered unlikely to affect the subject site. Other potential secondary seismic hazards: tsunami, and seiches flooding due to reservoir failure are considered nil due to the site location, and nature of the bedrock deposits, 7A 1 1 1 I I I 1 I I I I I I 1 I I I I I -7- Lakeshore Engineering Project No. 02-45PI NPC IN: 0020019,01 January 20, 2003 ~ ~.4 SAi~mir.: nA~ign CritAri~ _ Q711RC _ 97 UBC presents the following data based on known or assumed parameters as outlined in the tables Section 16, Volume II, 97 UBC, Moment magnitude used is for Wildomar Fault (Elsinore Fault - Temecula Segment) (worst case) 6,8Mw & 7,5M: Seismic Zone (UBC Figure 16-2) Seismic Zone Factor 'Z' (UBC Table 16-1) Seismic Source Type (UBC Table 16-U) Soil Profile Type (UBC Table 16-J) Seismic Coefficient 'Ca' (UBC Table 16-Q) Seismic Coefficient 'Cy' (UBC Table 16-R) Near Source Factor 'Na' (UBC Table 16-S) Near Source Factor 'Ny' (UBC Table 16-T) zone 4 0,40 (no units) 'B' Sc 0.40 Na 0,56 Ny 1,0 (no units) 1.2 (no units) Additional explanation as to the origins of these data can be acquired in Volume 2, Chapter 16, Division IV _ Earthquake Design, Pages 2-9 thru 2-38, 97 UBC. The site has been reviewed by the Engineering Geologist for Soil Profile, and based on the observed geologic conditions at the site, has been classified as a stiff soil 1 soft bedrock site - soil profile Sc for the subject property, The shear wave velocity at the site has not been measured, A shear wave velocity of 1207.4 ftIsec for Pleistocene alluvium (younger Quaternary), and soft sedimentary bedrock (Pauba Fm.) is applied to the subject site based on observations by the geologist (USGS Site Response Maps for the Los Angeles Region, Table 3, Average Amplification). However, some reviewing agencies refuse to accept the engineering geologist's soil profile classification without on-site shear wave velocity measurements, These measurements, when taken by the geophysicists in an on-site bore hoie, are very expensive relative to the project cost as a whole. In the "hsence of direct me"surement data for the single f"mily residenti,,' huilding site the reported soil profile rem"ins as c1"ssified by the gAnlogist but the dient in orner to meet the reqlJirF=!mAnts of the reviewing i=lgenr"..}' m~y h<=lVA to ~mhmit structur,,1 engineering C'.alcul"tions including base shear as Sn the LJBC97 default v"lue for soil profile This will depend on the rp.~ponsA of the reviewing ;::tgp.nr.y The site is located in an area of high regional seismicity based on UBC Map Figure 16-2, UBC 97 Map Book: 'Maps of Known Active Fault Near-Source Zones in California and Adjacent Portions of Nevada' have been used to locate and classify faulting for use in the above-tabled values, (see Figure 7, UBC97 AFNSZ Map 0-34). 3 1; I "nd",lide Pnh.nti"l _ The site is no located in within any Landslide Hazard Zone ands there is no Landslide Hazard Zone Map published for the local area (DMG). The Temecula Plateau (elevated older alluvial plain - Pauba sandstone) is not known for landslide development and is considered a low landslide potential area by most geologists. Landsliding or large scale slumping on the natural slopes was not observed at the site or in the local vicinity. :l R I iqIlAf:u~tinn Pnh~nti::d _ The site is no located in within any Seismic Hazard Zone (Liquefaction Zone) ands there is no Seismic Hazard Zone Map published for the local area (DMG). The site does not lie within a Riverside County Seismic Hazard Zone (for Liquefaction), The elevated portions of the Temecula Plateau (older alluvial plain - Pauba sandstone) is not susceptible to liquefaction due to the dense and partially cemented nature of the sandstone bedrock, The potential, from a geological point of view, for liquefaction is ~ considered nil. ;;r I I I I I I I I I I I I I I I I I I I -8- Lakeshore Engineering Project No. 0245PI NPC IN: 0020019.01 January 20, 2003 40 CONCIII!;ION!; R. RFCOMMFNnATION!;- 41 ~nnr.hndnn~_ . The subject site is suitable, in terms of the on site geologic conditions, for the proposed residential construction. Topsoils and Pauba Fm. sandstone bedrock should not present any significant geologic impediment to the excavation of the residential building pad and foundation footings, . The subject site is close to (2.0 mile) the Wildomar Fault Zone (Elsinore Fault-Temecula Segment 97UBC), There are no reported or mapped traces of the fault close to or on the subject site. Strong groundshaking (secondary seismic hazard) is considered a possibility should a medium to large earthquake event occur on the Wildomar Fault adjacent or close to the subject site, 4 2 Rp.r.:nmmp.nrl::lltinnA- . All foundation and/or retaining wall footings excavations, and cut slopes exceeding 10 feet in height should be inspected for competency by the soils engineer or the engineering geologist prior to the setting of form boards, reinforcing steel bar, or the cutting of any proposed slope, in order to confinm suspected geologic conditions, . Seismicity - The subject site should perform as a stiff soil 1 soft bedrock site. Soil profile of Sc- Pauba Sandstone soft bedrock should be used, Near Source Factor N. = 1,0, Near Source Factor Nv = 1,2. (see Figure 5, Active Fault Near-Source Zone Map). . Grnllndshaking - Due to close proximity of the active Wildomar Fault, the structural engineer should consider seismic peak accelerations and groundshaking criteria in the steel reinforcing design for the residential foundation, . Drainage Contrnl - Any proposed cut slope should have a drainage V brow ditch (24" wide, 12" deep) cut across the top of the proposed cut slope, set back 2 feet from the top of slope, The brow ditch should be lined with concrete grout. Drainage from all sources should not be allowed to flow over any proposed cut or fill slope faces, . I andscape Vegetation - Any proposed cut slopes should be planted with standard grasses and indigenous plants (hydro seed) possibly using a landscape stability growth net on the slope face, Deep-rooted vegetation should be planted in order to increase slope surficial stability over time. All landscaping design and plant type should conform to Riverside County landscaping guidelines, "v'V I I I I I I I I I I I I I I I I I I I -9- Lakeshore Engineering Project No, 02-45PI NPC IN: 0020019,01 January 20, 2003 1; n IIMITATION~_ This Engineering Geologic report section has been completed by Jonathan I. Rossi, Consulting Geologist, and licensed or certified subcontractors to Nevada Pacific Consultants. It should be noted that J,L. Rossi, Consulting Geologist has been retained for the purposes of providing geologic interpretation of existing and gathered data, and to provide the geology portion of the Preliminary Geotechnical Investigation. Our conclusions and recommendations are based solely on the data made available to us from one site visit, information made available by Lakeshore Engineering, and information made available by the Client. Our subsurface investigation was limited to shallow hand-dug pits, and an examination of existing cut slopes at the site and in the local area, Our work has been performed in accordance with the professional practices currently accepted in the Geotechnical Consulting Industry today. No warranty is either expressed or implied. Should you have any questions concerning this Letter Report of Existing Geologic Seismic Conditions please do not hesitate to contact me at (909) 244-2913, '--&~- -.......-::"-'. -F~'~ "t,'{~.~; ~':~I -. ~ .I <"~:,\:~' . ~~O(.,>\ t,,<J./ ',~--' .....-, A" . -.' '\ ~\\\ 5 ", f' ':::'~':" ',' \ .: ~', . '.: \ -, :~-.l-.'- f u., '-\ .. , '\., .' , d \ .. +-, ~. - -' , ~ 'f ,~ ~ '- ',";- ~~ ,\ /1 ..-' .. I . ,-' _ / -:r", -- :.' . ....o-=\.-::~ . SINCERELY YOURS; Jo C an L. Rossi, Con ulting Geologist 1460 ?g'!7 I I I I I I I I I I I I I I I I I I I -10- Lakeshore Engineering Project No, 02-45PI NPC IN: 0020019,01 January 20, 2003 REFERENCES Association of Engineering Geologist, 1973 - Earthquake Recurrence Intervals on Major Faults in Southern California, AEG Special Publication October 1973; D,L. Lamar, P.M. Merifield, R.J. Proctor. California Division of Mines & Geology - 1974; Map Sheet 23, Maximum Credible Rock Accelerations; R. Greensfelder. ---- 1992; Peak Acceleration from Maximum Credible Earthquakes in Ca.; DMG Open-File Report 92-1; L. Mualchin, & A.L. Jones. --- 1990; CDMG Map Sheet 54; unpublished for CalTrans. ---- 1954; CDMG SR 43; Geology of a Portion of the Elsinore fault Zone, California; John F. Mann, Jr, ----- 1977; CDMG SR 131; Recency & Character of faulting Along the Elsinore Fault Zone in Southern California; M.P, Kennedy ----- 1988 - Summary Report: Fault Evaluation Program, 1986-1987, Mojave Desert and Other Areas- Open File Report 88-1 LA; E.w. Hart, W.A. Bryant, J.E. Kahle, M,W. Manson, & E,J. Bortugno, ---- 1967 - Geologic Map of California, Map No, 1, Santa Ana Sheet; Jennings, C, W. ---- 1983 - The 1983 Coalinga, California Earthquakes, CDMG Special Publication 66, J,H,Bennett & R.W.Sherburne, Editors. Dudley, Paul H., 1935 - Geology of a Portion of the Perris Block, Southern California; California Division of Mines, California Journal of Mines & Geology Vol. 31, No, 4, October 1935, Earthquake Engineering Research Institute, 1982 - Ground Motion and Soil Liquefaction During Earthquakes; H.Bolton Seed & I.M. Idriss. Pub: EERI Berkley, California,; ISBN 0943198240 Earthquake Engineering, 1970 - Robert Wiegel, Coordinating Editor; Pub: Prentice-Hall, N,J., ISBN 132226464. Earthquake Engineering, Damage Assessment and Structural Design, 1983 _ S.F. Borg; Pub:Wiely Heyden, LId,; ISBN 0471262617. Geological Society of America, 1982 - Neotectonics in Southern California, Guidebook Field Trip No, 3, ~1~ . ------- 1986 - Neotectonics and Faulting in Southern California, Guidebook Field Trips 10, 12, 18, ---------- 1987 - Paleoseismicity and Active Tectonics, The Structural Geology and Tectonics Division, GSA. ~ 1 I I 1 I I I I I I I I I I I I I 1 I -11- Lakeshore Engineering Project No, 02-45PI NPC IN: 0020019.01 January 20, 2003 REFERENCES Grey, Clifflon H.,Jr, 1961 - Geology of the Corona South Quadrangle and the Santa Ana Narrows Area, Riverside, Orange & San Bernardino Counties, California" and Mines and Mineral Deposits of the Corona South Quadrangle, Riverside and Orange Counties, California; California Division of Mines and Geology Bulletin 178, Instution of Mining & Metallurgy, 1981 - Rock Slope Engineering, 3rd Edition; E. Hoek & J,w. Bray; Pub: Ins!. Mining & Metallurgy, London ISBN 0900488573 South Coast Geological Society, 1983 - Geology of the Northern Elsinore Trough, Annual Field Trip _ 1983. United States Geologic Survey - 1985; PP 1306; 'Earthquake Hazards in the Los Angeles Region'; J.1. Ziony. Webber, Harold F,,1977 - Seismic Hazards Related to Geologic Factors, Elsinore and Chino Fault Zones, Northwestern Riverside County, California, MAPS IITII 17Fn USGS 71/2' Murrieta Quadrangle Topographic Map 1973 rev, USGS 71/2' Bachelor Mtn. Topographic Map 1972 CDMG Special Study Zone Map (Earthquake Fault Zone Map), Murrieta Quadrangle 71/2' Revised Official Map January 1,1990. -- 1967 - Geologic Map of California, Map No, 1, Santa Ana Sheet; Jennings, C, W. / "b'O I 1 1 1 I I I I I I I I I I I I I I I -12- Lakeshore Engineering Project No, 02-45PI NPC IN: 0020019,01 January 20, 2003 SCEC Magnitude Update 2000 - Multiple Magnitudes? As it happened with the introduction of the intensity scale, so too did Richter's scale spawn new variations on the idea of magnitude, But instead of being rooted in personal preferences, this multiplicity of magnitude scales was created to provide new ways to rate earthquake energy using different types of instrumentally- measurable data, This has given seismologists an enhanced ability to quantify earthquakes, But when multiple ratings from different scales are applied to the same earthquake, it can cause confusion among members of the public, M.7,S M,,7.3 m.6,2 Landers Earthquake June 2ll. 1992 '" M,,=1.1xlO Nm Though initial magnitude estimates are sometimes revised slightly as more data is gathered and analyzed, a lot of the claims that the magnitude of an earthquake was "altered" by some institution (e,g. locai government, in one popular urban legend) for some reason (avoidance of a property-lax-waiving law, in the same legend) are rooted in ignorance about the existence of multiple magnitude scales, and confusion between them, Steps have been Iaken to try and keep the scales similar to each other, so that we can talk generically about a "magnitude 6 earthquake" without specifying the exact scale used. Still, different scales don't usually produce the same magnitude rating for any given large earthquake, To understand why this is, it helps to know what some of the different scales are, and what they measure. . MLV Local Magnitude: Based upon the Richter's original magnitude scale, this is a measure of the amplitude of the maximum trace deflection (i.e, the distance between the resting position of the seismogram needle and the crest of the largest squiggle it records) versus distance from the source, Large earthquakes can produce so much shaking that seismograph traces go "off-scale", leading to a "saturation" in the maximum amplitude of deflection. Consequently, local magnitude tends to be used only for earthquakes smaller than about magnitude 6, . Mov Seismic Moment: Not actually a magnitude scale, seismic moment is an estimate of the energy of an earthquake, and as such, is typically given in units of Newton-meters (Nm), A magnitude 6 earthquake has a moment of about 1.0 . 10'8 Nm, roughly the energy that would be released by the detonation of 6,000 tons of TNT. On the next page, you'll be introduced to a way of calculating the seismic moment of an earthquake, . Mwv Moment Magnitude: The moment magnitude scale is a way of rating the seismic moment of an earthquake with a simple, logarithmic numerical scale similar to the original Richter magnitude scale, Because it does not "saturate" the way local magnitude does, it is used for large earthquakes - those that would have a local magnitude of about 6 or larger. . Msv Surface-wave Magnitude: Surface-wave magnitude is calculated using the amplitude, on a long- period vertical seismometer, of surface waves with a 20-second period. . mbV Body-wave Magnitude: Defined by Gutenberg and Richter in 1956, body-wave magnitude uses only short-period P waves to arrive at a numerical magnitude rating. This rating is useful for judging the size of explosions (including nuclear bomb tests!), since they tend to produce smaller S waves than natural earthquakes, All magnitude scales, including those listed above, are a way to assess the energy of an earthquake. You've seen how that energy can be transmitted as seismic waves, causing the shaking we feel and call an earthquake, but now consider this: from where does that energy originate? What generates it, and what releases it? ~(, 1 Symbol Major DIvisions Letter Name Hatching Color (1) (2) (3) (4) (5) (6) \l-, Well-graded gravels or gravel- GW :',Cj sand mixtures, little or no fines ,0, ." " ... c: Poorly graded gra\'els or gravel- GP :. sand mixtures, little Of no fines Gravel Ii and : Silty gravels, gravel-sand-silt Gravelly 'd mixtures Soils I _ , ~ I ~ - GM>-- oS ;g -, 'u a; ,- >- ." , ~ Clayey gra\'els, gravel-sand-clay ~ GC '; mixtures " .. .:- , Well.graded sands or gravelly ~ ~ SW . .. " ... ." sands, little or no fines ,. ~ 0 .. c: Poorly graded sands or gravelly U S1' . .. .. . .. sands, little or no fines Sand : I Silty sands, sand-silt mixtures and 'd Sandy ,- , Soils SM :.... ~ -I oS ,~ ~ , .- g Cla)'ey sands, sand-clay mixtures , Inorganic silts and very flnc sands, ~L rock flour, silty or clayey line sands, or clayey silts with slight Sills plasticity and ~ Inorganic clays of low to medium Clays ~ .!!l CL " plasticity, gravelly clays, sandy (LL < 50) .. '0 .., clays, silty clays, lean clays ell .., lil!l~ Organic silts and organic silt..clays ~ OL c of low plasticity '; " III .. Inorganic silts, micaceous Of , ~ MH diatomaceous fine sandy or silty c t;: Silts soils, elastic silts and ~ " Inorganic clays of high plasticity, Clays eH ~ (LL > 50) al fat clays '0 Organic clays ol medium to high OH ~ plasticity. organic silts Highly Organic PI = Orange Peat and other highly organic soils Soils -- . I I 1 I I I GRAVEL I 2,0 GRAVEL l 2,0 Te:durcd OaujflcalKln $pe<iflcatiaru U.S. Dopt. of Al'J1culture-1951 SAND SILT CLAY 0.002 0.05 AASHO SAND SILT 0.074 (200-nlesh sievt!) C 0.005 CLAY CM and BPR GRAVEL ~AND I StLT 2.0 0.05 CCL~~ 0.005 ~OIL GRADATION COMPARSION CHART I UNIFIED SOILS CLASSIFICATION ......... SYSTEM CHART I I 1 I I I I SOIL - GRADATION '00 ;G I ~ 80 ~ i60 " ... j" o 1005C 2.0 1.0 O~ 0-2 0.1 O~ CC~ co:. 0005 o.ooi PO<'"tlc1e Ojom"'er if, "'... SAND r-;.~' ., ~ Pwuont SILT Fill. 2-6. Triang"lor fi;lgwlkalion dlOfI. .ioJ., Ca.pI of Enstin..n, U. S. A'.J) I Low.. lNui..ippi Vgll.J Di'4'i. I GRAVtL I~ I LAKESHORE Engineering SOIL CLASSIFICATION SYSTEMS Co"8UII.ng C'vU Engln_rlng e"d 08010101.8'8 % . ... TRINARY SOILS DIAGRAM \ ....s,c ~OIl.S (HOINU_IN!;; o s,z~ ,i,".Is S~ncI... 20IQDOS...", Sill...OO!Jh1o'Orbm", C/~y .. Lus MrM 0005"", .0 .. ~ ,?I La Bonte - Lot 78, Tract 3929, Meadowview DATE'12/18102 IN' 02-084 SCALE. F m' "'C:f "l:1 ,. C1 .<> >oj >oj ..; m coo -i 0 ...... '-'. l....J. I-ft-' "d tI) (1) ..; 0 ann C:::G1('Ortrt CH ::> mn ... Z Z '" .. e ll> a a cr '" '" .. .., c ,. ;;j ~ " ~ ; t'" o "" "" r> c.. '" '< m Z C1 H Z m m '" ..... Z C'l "0 '" o "0 m '" ..; ..... m '" t'" m o ..... n " ll> < ... ll> .... ... o ...' ::> 0 .. ::> ~..; '" ~ ~ :I: ~~~ CO Zt"" ~ .....0 ..;C'l , ;:; '- c m '" n '" ..... "0 ..; ..... o Z ~ ~ ~ ,'" ~ ~ ~ ~~~~ ~l~~ ~l'~,~ ~ i (~~~~ ~ ~ ...~,:'" -5. ~,. ~~ l" ~t~ ~~ ~~!~.. ~~~[\~~ l' ~~~~ ~~~ ~. ~~ d~~~~ ~ ~~~ d~l~~ ~~~ ~ ~ ~ ~ ~ ,~~ ~ ~:~d<l:! ~i'!: ~~~~l ~d C'l !i;: "0 :I: ..... 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