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HomeMy WebLinkAboutParcel Map 18254 Parcel 19 Geotechnical Report Riverside County 38655 Sky Canyon Drive,Suite A Murrieta,Catif.,nu 92563 951-600-9271 past+present+future its in our science Engineers,Geologists Environmental Scientists February 2, 2009 J.N. 290-08 JOHN FIRESTONE HUB 3, LLC 92 Linda Isle Newport Beach, California 92660 C/O Mr. Benjamin J. Stables III ARMSTRONG & BROOKS CONSULTING ENGINEERS 1530 Consumer Circle, Suite B Corona, California 92880 Subject: Geotechnical Update Letter, Proposed Ridge Park Plaza Development, Ridge Park Drive and Vincent Moraga Avenue, City of Temecula, Riverside County, California References: 1) Petra Geotechnical, Inc., 2001, Geotechnical Investigation, North Village, Proposed Commercial Development, City of Temecula, Riverside County, California,prepared for RJH Development; P.N. 461-00 dated January 11. 2) Armstrong &Brooks Consulting Engineers, Conceptual Grading Plan for Ridge Park Plaza, Temecula, CA, 30-scale, 11 sheets. Dear Mr. Stables: In accordance with your request, Petra Geotechnical, Inc. (Petra)has prepared this geotechnical update letter regarding the current condition of the subject site located in the City of Temecula, Riverside County, California. Our original geotechnical investigation for this site was prepared on January 11, 2001 (Petra, 2001). The site has not yet been developed, since mass-grading of the eastern portion of the site in 1989. The purpose of this letter was to review new project information and, based on this information provide an update to our original report. Our scope of services was as follows. HUB 3,LLC February 2, 2009 Ridge Park Plazafremecula J.N. 290-08 Page 2 • Site reconnaissance of current site conditions. • Review of Petra's and other consultant's previous reports concerning soil and geologic conditions at this site. • Review of current conceptual grading and architectural plans for the site and structures. A site reconnaissance visit was conducted by a Petra engineer and geologist in September 2008. Based on our observations, the site has remained essentially unchanged since preparation of our referenced geotechnical investigation report (Petra, 2001). The only notable exception is with regards to the ascending cut slope and upper mass-graded pad areas which have undergone additional erosion since 2001. After reviewing the architectural and conceptual grading plans grading of the site and the proposed structures, the development concept has change significantly since our last report was issued. The project remains feasible from a geotechnical standpoint, however, additional grading plan review, geotechnical subsurface exploration, and seismic-refraction surveys will be required once grading and building plans are finalized. Detailed grading and foundation design recommendations would be provided based on the type of structures proposed. We appreciate this opportunity to be of service. If you have questions, please contact this office. Respectfully submitted, PETRA GEOTECHNICAL, INC. gS\ONAL QF-. aDOUGLSSL.JOHNSTO. N� CERVI // ��(/ • NO. 24 7 • PR FFSSI, ED ENGINEERING '�� SON R. Douglass L. Johnston, CEG GEOLOGIST ��e Gra son R. Walker, 9�m Senior Project Geologist T9pF CAti�FOP Principal Engineer * c Xp�3 3j/o9 �' _2�ICHNICP� Distribution: (4) Addressee F0FCALIFOFN�P Riverside County 4�.= 38655 Sky Canyon Drive.Suite A �-.. Murrieta,California 92563 951-600-9271 past+present+futun its in our scicnn Engineers.Geologist: Environmental Scientist, February 2, 2009 J.N. 290-08 HUB 3, LLC 92 Linda Isle Newport Beach, California 92660 C/O Mr. Benjamin J. Stables III ARMSTRONG & BROOKS CONSULTING ENGINEERS 1530 Consumer Circle, Suite B Corona, California 92880 Subject: Updated Earthquake Loads Parameters Based on the 2007 California Building Code Section 1613, Proposed Ridge Park Development, Ridge Park Drive and Vincent Moraga Avenue, City of Temecula,Riverside County, California References: 1) International Conference of Building Officials, 2007, 2007 California Building Code, California Code of Regulations, Title 24, Par 2, Volume 2 of 2, California Building Standards Commission, Based on 2006 International Building Code, 2007 California Historical Building Code, Title 24, Par 8, 2007 California Existing Building Code, Title 24, Part 10. 2) Petra Geotechnical, Inc., 2001, Geotechnical Investigation, North Village, Proposed Commercial Development, City of Temecula, Riverside County, California, prepared for RJH Development; P.N. 461-00 dated January 11. Dear Mr. Stables: As requested, Petra Geotechnical, Inc. (Petra) has prepared the following updated Earthquake Loads parameters based on the 2007 California Building Code (CBC) Section 1613 for the proposed development, located south of Ridge Park Drive and Vincent Moraga Avenue in the City of Temecula, California. This information supersedes the seismic-design parameters presented in our previous report for the subject site (Petra, 2001) which were based on the 1997 CBC. HUB 3, LLC February 2, 2009 Ridge Park Plaza/Temecula J.N. 290-08 Page 2 2007 CBC Section 1613,Earthquake Loads Site Class Definition (Table 1613.5.2) D Mapped Spectral Response Acceleration Parameter, S, (Figure 1613.5(3)for 0.2 second) 1.98 Mapped Spectral Response Acceleration Parameter, S, (Figure 1613.5(4)for 1.0 second) 0.75 Site Coefficient,F,(Table 1613.5.3(1)short period) 1.0 Site Coefficient,F (Table 1613.5.3(2) 1-second period) 1.5 Adjusted Maximum Considered Earthquake Spectral Response Acceleration Parameter, SMs 198 (Eq. 16-37 Adjusted Maximum Considered Earthquake Spectral Response Acceleration Parameter,SMi 1.12 Design Spectral Response Acceleration Parameter, Sos (Eq. 16-39) 1.32 Design Spectral Response Acceleration Parameter,SDI(Eq. 16-40) 0.75 We appreciate this opportunity to be of service. If you have questions, please contact this office. Respectfully submitted, PETRA GEOTECIINICAL, INC. � �ySON R. t�S_ W � ce cc GE 871 �' m G son R. Walker, GE * '03131109 Principal Engineer g<�16 HNICP� CALIFOR�\P Distribution: (4) Addressee f : PETRA !r COSTa hnESA•SAN DtEGO•iEtnECULA•LCS aNGELES t. . Januan, 1 I. 2001 CJ.N. 461 -00 (` RJII DEVELOPMENT c/o The Keith Companies 22690 Cactus Avenue [ . Moreno Valley, California 92553 f Attention: Mr. Richard Haness i Subject: Geotechnical Investigation, North Village, Proposed Commercial Development, City of Temecula, Riverside County, California Petra Geoteclutical, Inc. is pleased to submit herewith our geotechnical investigation report for North Village, a commercial development proposed south-southwest of Ridge Park Drive and Vincent Moraga Drive in the City of Temecula. California This work was performed in accordance with die scope of cork outlined in our Proposal Nos.1295-00 dated ,august J. 2000, and 31 5.00 dated November 28 and December 5. 2000. This report presents the results of our field investigation, laboratory testing and our engineeringjudgement, opinions, conclusions and recommendations pertaining to rgeotechnical design aspects of the proposed deg elopmem. It has been a pleasure to be of service to you on this project. Should you have any e- questions regarding the contents of this report or should you require additional information, please do not hesitate to contact us. i Respectfully submitted, fPETRA GEOTECHNICAL, INC- Mark Bergm Vice President LAB/CB/GRW/MB/keb Distribution: (3) Addressee (3) The Keith Companies Attention: Mr. Kevin Everett PEIRAGE011C19dCAL W. "?0 Commerce Centel or.Ste. 103 IemeCUO.CA 92590 let.(909)699-6193 - For.(909)699-6197 t . RJII DEVELOPMENT January 11. 2001 � . North Village/Tenrecula J.N. 461-00 Page i L, TABLE OF CONTENTS Section Pate r INTRODUCTION - . . . - . . . . . . Purpose and Scope of Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LOCATION AND SITE DESCRJPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 PROPOSED GRADING AND DEVELOPMENT . . . . . . . . . . . . . . . . . . . . . . . . . 4 f ` BACKGPOUND INFORMATION/PREVIOUS STUDIES . . . . . . . . . . . 5 I INVESTIGATION AND LABORATORY TESTING . . . . . . . . . . . . . . . . . . . . . . 7 Field Exploration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Laboratory Testing . . . . . . . . - . . . . . . 8 FINDINGS . . . . . . . . . . . . . . . . 9 Regional Geologic Selling . . . . . . . . . 9 Local Geology and Soil Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Groundwater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . II Faulting . . . Landslides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 y Flooding Potential . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 CONCLUSIONS AND RECOMMENDATIONS . . . . . . . . . . . . . . . . . . . . . . . . 12 General . . . . . . . . . . . . . . . . Grading-Plan Review and Additional Exploration . . . . . . . . . . . . . . . . . . . . . . 13 J Earthwork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 i• General Earthwork and Grading Specifications . . . . . . . . . . . . . . . . 13 Clearing and Grubbing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Excavation Characteristics and Bedrock Rippability . . . . - . . . - - . . 14 ' Groundwaler . . . . . . I5 . . . . . . . . . . . . . . . . . . . . . . . . . . Ground Preparation - Fill Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 ' Canyon Subdrains . . . . . . . . . . . . . . . . 16 Disposal of Oversize Rock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Fill Placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Benching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 ProcessingofCul Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Overexcavation of Cut Lots and Cut Streets in Bedrock Areas . . . . 17 Cut/Fill Transition Lots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 d. i I I ' 12JF1 DEVELOPMENT January 1 I, 2001 North Village/Cemecula J.N. 461-00 Page ii TABLE OF CONTENTS (Continued) Shallow-Fill to Deep-Fill Lots . . . . . . . . . . . . . . . . . . . :. . . . - - - - . 18 CutSlopes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Fill Slopes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Shrinkage, Bulking and Subsidence . . . . . . . . . . . . . . . . . . . . . . . . . 21 j Geoteclinical Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2? l Post-Grading Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Slope Landscaping and Maintenance . . . . . . . . . . . . . . . . . . . . . . . . 22 Natural Slopes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Utility Trenches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Site Drainage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Seismic Design Considerations . . . ... . . . . . . . . . . . . . . . . . . . ... . .. . . . 26 Ground Motions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Secondary Effects of Seismic Activity . . . . . . . . . . . . . . . . . . . . . . . 28 Tentative Foundation-Design Recommendations - - - - - - - - - - - - - - - - - - - - - - 29 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Allowable-Bearing Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Settlement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21) Lateral Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Footing Setbacks From Descending Slopes . . . . . . . . . . . . . . 31 Building Clearances From Ascending Slopes . . . . . . . . . . 31 Fooling Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 IExpansive Soil Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Retaining Walls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Allowable Bearing Values and Lateral Resistance . . . . . . . . . . . . . . 36 Footing Embedments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Active and Al-Rest Earth Pressures . . . . . . . . . . . . . . . . . . . . . . . . . . 37 Drainage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 t Temporary Excavations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Wall Backfill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 CementType . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Soluble-Sulfate Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 GRADING-PLAN REVIEW AND CONSTRUCTION SERVICES . . . . . . . . . . 39 INVESTIGATION LIMITATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 t i C - RJH DEVELOPNIENT January 11, 2001 North Village/Temecula J.N. 461-00 ( Page iii ` TABLE OF CONTENTS (Continued) Figure I - Site Location Map Figure 2 - Geoteclinical Cross-Sections A-A', B-B' and C-C' References Plate I - Geolechnical Map (in pocket) CAppendices Appendix A - Logs of Borings and Test Pits Appendix B - Laboratory Test Criteria/Laboratory Test Data Appendix C - Slope-Stability Calculations Appendix D - Standard Grading Specifications 1 r f: u i ti 4 rF 1 J v f - r GEOTECHNICAL INVESTIGATION, NORTH VILLAGE [ ; PROPOSED COMMERCIAL DEVELOPMENT CITY OF TEMECULA, RIVERSIDE COUNTY, CALIFOULNIA L INTRODUCTION I, Petra Geo[echnical, Inc. (Petra) is pleased to present this geotechnical investigation report for [he subject property. The purposes of this investigation %vere to determine the nature of surface- and subsurface-soil and bedrock conditions, evaluate their in- place characteristics, and then provide preliminary grading and foundation design [j 9 recommendal ions based on the accompanying 100-scale conceptual grading plan prepared by The Keith Companies (TKC). The conceptual grading plan was used as the base map to show geologic conditions within the subject site and is enclosed as Plate I. Subsurface exploration within the subject property was performed concurrently %vith [; an investigation of Villages of Old Town , a proposed residential development located I south-southeasterly of the subject site. The results of the subsurface exploration that included both sites was originally presented in one repon under Petra's Job f' Number 315-00. However, pursuant to the Client's request, we have prepared separate 4• geolechnical reports for each project. This report presents conclusions and Ft zf recommendal ions pertaining to North Village. The other report addresses the proposed residential development, Villages of Old Town, under Petra's Job Number 315-00. This report, however, includes boring and test pit logs and laboratory test data k r accumulated for both sites. a E ] Purpose and Scope of Services t The purposes of[his investigation were to obtain information on the subsurface soil and geologic conditions within the subject site, evaluate the data and then provide preliminary grading and foundation design recommendations. The scope of our investigation included the following. i I RHI DEVELOPMENT January 11. M01 i North Villagerremecula J.N. 461-00 Page 2 Review of publislied and unpublished literature and geotechnical maps.pertaining to active and potentially active faults that lie in proximity to the site which may lave an impact on the proposed development. This included a review of data acquired by Leighton and Associates, Inc. (Leighton), Soil Tech, Inc. (Soil Tech) and Geotechnical & Environmental Engineers, Inc. (GEE) for the subject site and/or adjacent properties. A complete list of references is attached. I • Review and interpretation of stereo-aerial photographs dating from 1962 to 2000. I • Field recorutaissance'to observe existing site conditions. • Geologic mapping'of the site. • Drilling, logging and selective sampling of duee hollow-stem auger borings to f depths of 26 to 43 feet (Borings B-I through B-3). t Drilling, logging and selective sampling of one bucket-auger boring to a depth of 43 feet (Boring B-8). Excavation, logging and selective sampling of three test pits with a backhoe to f depths of 3 to 14 feet (Test Pits Tf -31, TP-34 and,TP'-')5). Laboratory testing and analysis of represenlalive samples of soil and bedrock f materials (bulk and undisturbed) obtained, from the borings and test pits to determine their engineering properties. • Preparation of the enclosed geolechnical map (Plate 1) and three geologic cross- sections (A-A'. B-B' and C-C) through the most critical areas to show the highest proposed cut and fill slopes, as well as interpolated and extrapolated geologic conditions (Figure 2). ! • Engineering and geologic analysis of the data with respect to the proposed development. • Performing slope stability calculations to evaluate the gross and surficial stability of the highest proposed cut and fill slopes. - An evaluation of faulting and seismicity of the region as it pertains to the_site. - Preparation of this report presenting our findings, conclusions and preliminary i geolechnical recommendations for the proposed development. RAI DEVELOPMENT January H. 2001 ` North Villagerremecula 1.N. 461-00 Page 3 LOCATION AND SITE DESCRIPTION 1 The subject site is located south-southwest of the intersection of Ridge Park Drive and t` Vincent Momga Drive in the City of Temecula, California. The general location and configuration ofthesiteareshownon Figure 1. The irregular-shaped property consists I of approximately 70 acres and is bordered on the southwest by (lie eastern foothills of the Santa Ana Mountains. Vacant land exists to the south and west and residential and commercial developments exist to the north and northeast. The topography over the site is generally characterized by aseries ofeasterly-trending natural slopes. Iota-rolling hills and associated intervening canyons and tributary + drainages. Natural slope gradients vary from approximately 5:1 (horizontal:vertical [h:v]) to locally as steep as 1:1 (h:v) along steep-sided natural drainages. [ Two relatively large mass-graded pads exist within the site. south of Ridge Park Drive. These two level pads have been graded to a gentle sheet-tloxv configuration and are (_ separated by an east-facing, approximately 25- to 30-foot-high, 2:1 (Irv) graded slope d (` consisting of both cut and fill. The mass-graded pads are also bordered by several 2:1 l (h:v) cut and fill slopes. Maximum heights of these perimeter cut and fill slopes are approximately 30 feet and 50 feet, respectively. Irrigation lines were observed on some slopes and each were noted to be covered with a variable growth of weeds. In i addition, most of the graded slopes have been landscaped with a low groundcover, as well as occasional small trees and shrubs. Concrete terrace drains exist on the fill slopes bordering the easterly and southerly sides of the lower mass-graded pad. A majority of the fill slope surfaces were observed to be in a reasonably good condition, since their construction in 1989 and exhibit only a slight degree of erosion: however, L: some localized erosion gullies varying from approximately 1 to 2 feet deep were observed. Moderate to significant erosion was observed on cut slopes excavated in ' Pauba sandstone and on cut slopes that have not been landscaped or possess only i RJH DEVELOPMENT January 11, 2001 North Village/Temecula 1.N. 461 -00 Page 4 minimal vegetation. The cut slope ascending above and westerly of the upper mass- graded pad exhibits the most significant erosion with rills up to approximately 3 feet i deep. Moderate erosion has also occurred over the surface of the upper mass-graded pad with erosion gullies up to approximately 2 feet deep. The surface of the lower 1 mass-graded pad exhibits a much lesser degree of erosion. i r Two cut slopes also exist in the northem portion-of the property that ascend to a ma:,iinum height of approximately.70 feel above an existing commercial development. These two cut slopes appear to be well landscaped and routinely watered with an above-grade irrigation system. i Elevations across the site vary from approximately 1.020 feet above mean sea level i within the northeastern portion to. approximately 1,460. leer in the nortliwestem portion. Local drainage is generally directed towards the east into Murrieta Creek. i Electrical and communication utilities were noted along the sowh side of Ridge Park i Drive. Vegetation consists of a moderate to dense growth of fall, scrub brush over the natural portions of the site. Sparse weeds, construction debris organic debris and general household trash were also'observed in several areas on the Iwo mass-graded pads. PROPOSED GRADING AND DEVELOPMENT The enclosed 100-scale conceptional grading plan prepared by TKC (Plate 1) I indicates that three large mass-graded pads will be graded to accommodate construction of several commercial and retail structures. A school site is also planned on one of the parcels. Access to the site will be provided by Ridge Park Drive on the north and from a proposed extension of Vincent Moraga Drive into the development. c� RJH DEVELOPMENT January 11, 2001 North Village/Temecula J.N. 461 -00 Page 5 The Western Bypass Condor, a proposed major roadway; is planned to Ilse soull1west of the mass-graded building pads. C. fMaximum vertical depths of cut and fill associated with future grading are ` approximately 50 and 65 feel, respectively. The deepest cuts are associated widt the t' excavation of series of 1.5:1 (h:v)cut slopes along both sides of the Western Bypass Corridor. The proposed I.5:1 (h:v) cut slopes vary in height to a maximum of approximately 125 feet. The deepest fill is proposed within a natural drainage located r, in the northwestern portion of the subject site that will be crossed by the Westem { Bypass Corridor. Variable height , 2:1 (h:v) descending fill slopes are also planned on both sides of the roadway at this location. The proposed 2: 1 (h:%) fill slopes in this �4 area vary up to a maximum height of approximately 100 feet. Geologic Cross- Sections A-A', B-B' and C-C' (Figure 2) have been prepared to shoe the highest fJ proposed cut and fill slopes. BACKGROUND INFORMATION/PREVIOUS STUDIES �`. Based on a review of stereo-aerial photographs dated 1962, 1983 1995 and 2000, a majority of the site has essentially remained in a natural stale since 1962- The two t3 mass-graded level pads located within the northern portion of the site, south of Ridge F'• Park Drive, were rough-graded in 1989. In September of 1988, Leighton conducted a fault and liquefaction investigation of f . both the North Village and Villages of Old Town sites to study the Willard branch of The Elsinore fault zone as projected through the property by M.P. Kennedy in 1977. L. The fault and liquefaction investigation performed by Leighton included the Fr excavation of four fault trenches perpendicular to suspected traces of the Willard fault E ; zone and drilling of two exploratory borings to a maximum depth of 41 feel. Per f s RJH DEVELOPMENT January 11, 2001 North Village/Temecula 1.N. 461-00 Page 6 Leighton's reported findings, faulting and fault related features associated with the Willard fault zone were encountered in their exploratory Trench T-1,excavated across the north end of the North Village site- Leighton concluded that the faulting exhibited i' older weathered features, was confined to the igneous and metamorphic complex material and did not extend into or offset the overlying Holocene deposits. Leighton, ' therefore,concluded that faulting and fault related features of the Wildomar fault could be designated as Pre-Holocene or considered not active by California Slat,, definition and do not represent a potential hazard to site development. The approximate locations of life fault trenches (T-I and T-2) associated, with Leighton's fault investigation are shown on the enclosed geotechnical maps(Plate I). In April of.1989, Soil Tech performed a preliminary geotechnical investigation in the area of the two existing mass-graded pads located south of Ridge Park Drive. The approximate locations of eight exploratory.test'pits '(ST-2 tluough ST-9) excavated by Soil Tech within the limits of the graded pads.are shown on Plate I; however. it should be noted that the test pits were excavated prior to rough grading. Rough grading of the I two mass-graded pads was also performed in 1989 with observation and testing t services provided by Soil Tech. The rough grading resulted in cut-to-fill transitions crossing the building pads; however, the cut portions were reportedly overexcavated j to a depth of approximately 2 feel. The estimated contact (transition) between cut and ' fill is shown on Plate 1. Maximum vertical depths of cut and fill were approximately 50 and 35 feel, respectively. Subsequent to this rough grading, the site has remained I relatively unchanged from 1989 to present. In 1996, GEE performed a geotechnical investigation along the proposed Western Bypass Condor. Their subsurface investigation involved the drilling of large diameter borings in the areas of the proposed cut slopes to collect relatively undisturbed soil and j bedrock samples and assess the geologic structure of the bedrock. GEE observed i RJI4 DEVELOPMENT January 11, 2001 North Villagefrcmecula J.N. 4 61-00 Page 7 nearly vertical jointing and foliation within the metasiltstone, discontinuous jointing within the granitic bedrock and nearly horizontal bedding within the Pauba formational bedrock. Based on their slope stability analyses, GEE concluded that the cut and fill fslopes proposed along the Western Bypass Corridor will be grossly and surficially stable. Their slope stability analyses included a 125-Coot-high, 1.5:1 (h:v) cut slope excavated in Pauba formational bedrock, a 65-fool-high, 2:1 (h:v) cut slope excavated in the Bedford Canyon Formation and a 75-fool-high, 2:1 (h:v) fill slope. GEE also ' performed three seismic traverses to evaluate bedrock rippability. They concluded the _ majority of the bedrock should be rippable with a moderate to high degree ofdifficulry rwith possible localized deep cuts in granite and meta-silist one that may require blasting. l: INVESTIGATION AND LABOR.ATORYTFSTIN I ' ii Field Exploration r7 .a Subsurface exploration within the subject site was perfomted on August 21 and 26, tR 2000. concurrently with an investigation of Villages of Old Town, contiguous to the 4 south of the subject site. The subsurface exploration included the excavation of three test pits to depths ranging from 3 to 14 feet (TP-31,TP-34 and TP-35) using a rubber- Y tired backhoe and the drilling of three 8-inch-diameter, hollow-stem auger borings to st depths of 26 to 43 feet (B-I through B-3). A bucket-auger drill rig was also used to �e drill one exploratory boring to a depth of 43 feet (13-8). Exploratory locations were constrained within the North Village site due to steep terrain and dense vegetation. Prior to conducting the subsurface exploration, Underground Service Alert of Southern nCalifornia was contacted to locate any underground utilities. 'i Earth materials encountered within the exploratory test pits and borings were classified 1 and logged in accordance with the visual-manual procedures of the Unified Soil 1 RJH DEVELOPIJENT January 11 , 2001 North VillagefTernecula J.N. 461-00 1 Page 8 Classificalion System. The approximate locations of the exploratory borings and test i pits are shown on Plate 1 and descriptive logs are presented in Appendix A. For I convenience, exploration logs for both the North Village and Villages of Old Town i site are included in Appendix A. Associated with the subsurface exploration was the collection of bulk (disturbed) samples and relatively undisturbed samples of soil and bedrock materials for hboratory testing. R,eIali­ely undisturbed samples were obtained with a 3-inch- outside-diameter modified California split-spoon soil 'sampler lined with I-inch-high brass rings. The soil sampler was driven with successive 30-incli drops of a 140- i pound, free-fall sampling hammer. The central portions of the driven-core samples i were placed in sealed containers and transported.to our laboratory for testing. i I Laboratory Teslino Maximunn'dry density, expansion potential, soluble sulfate content, consolidation characteristics and shear strength were determined for selected disturbed (bulk) and undisturbed samples of soil and bedrock materials considered representative of those encountered. Moisture content and unit dry density were also determined for in-place soil and bedrock materials in representative strata. A brief description of laboratory test procedures and summaries of the lest data are presented in Appendix B. In-situ i moisture content and dry unit density are included in the exploration logs (Appendix A). An evaluation of the test data is renecied throughout the Conclusions and Recommendations Section of this report. i i I t RJH DEVELOPMENT January 11, 2001 North Village/Temecula J.N. 461-00 Page 9 FINDINGS Regional Geologic Selling Regionally, the site is located in the Peninsular Ranges Geomorphic Province of Califomia_ The Peninsular Ranges are characterized by steep, elongated valleys that trend west to northwest. The northwest-Irending topography is controlled by the Elsinore fault zone which extends from the San Gabriel River Valley southeasterly to the United Slates/Republic of Mexico border. The Santa Ana Mountains lie along the %vestem side of the Elsinore fault zone, while the Perris Block is located along the eastem side of the fault zone. The mountainous regions are underlain by Pre- Cretaceous, metasedimentary and metavolcanic rocks and Cretaceous plutonic rocks fof the Soutllem Califomia Balholith. Tertiary and quatemary rocks are generally comprised of nonmarine sediments consisting of sandstone. mudstones,conglomerates and occasional volcanic units. FF Locally, the site is located along the eastern foothills of the Santa Ana Mountains at I ' 4= the weslem margin of the Elsinore Trough. The mountains have been elevated as the n valley has subsided along the Willard and Murrieta Creek segments of the Elsinore I ' i`. fault zone. The Willard fault zone is a series of discontinuous faults which display high-angle normal movement. The Murriela Creek fault is considered active and the Willard fault has been determined to be inactive. (no movement within the Iasi 11,000 years) south of Rancho California Road where it appears Iha1 movement could be v i' transferred to the Wolf Valley branch of the Elsinore fault located east of Interstate 15. Vertical movement along(tie Willard fault is estimated to be 300 meters. Indications of faulting along the Willard fault include linear breaks in topography, sag ponds, 3 pressure ridges and flat irons. f 3 i i i RJH DEVELOPMENT January 11. 2001 North Village/Temecula J.N. 461-00 j Page 10 Local Ceoloov and Soil Conditions I i Soil and bedrock units encountered in the exploratory borings and test pits within the r ' l North Village site included documented artificial fill deposits, colluvium/topsoil, i Pauba fanglomerate,Pauba sandstone and Bedford Canyon metasilistone. Quaternary alluvial deposits also exist within the narrow canyons and tributary drainages crossing the site; however, these areas could not, be explored due to inaccessibility (sleep ilerrain). A general description of the soil and bedrock. materials observed on the site is provided in.the following paragraphs. i • Documented Artificial Fill (map svmbol: a1Y — Compacted fill deposits, I associated with 1989,grading operations, exist within the northeastern portion of the site. The compacted fills exist on and in the vicinity of the lwo mass-graded pads. The fill materials observed in Petra's exploratory Borings B-1 . B-2and B-3 consisted of sand arid silly sand with variable amounts of.gravel and cobbles. The soils were damp to moist, medium dense to depths of up to 3t feet due to weathering and erosion-and dense below. Petra's borings were extended througfi the fill and into the underlying bedrock for this investigation. Based on these borings. it appears that loose alluvial and/or colluvial soils were removed or ' adequately recompacled in-place prior to placing fill. • Quaternary Alluvium (rnap symboh Oal) — Quaternary alluvial deposits exist within the canyons and tributary drainages crossing the site. Due to steep terrain ! along the canyons and drainages, access was not possible with a backhoe or drill rig. However, based on test pits and borings excavated within the southerly 1 adjoining Villages of Old Town site,the alluvial deposits can generally be expected to consist of medium dense silly sand and/or sandy silt with occasional layers of clayey sand. Occasional to locally abundant metasiltstone cobbles and gravel can t also be generally anticipated. Test pits and/or borines are required.to determine the depths of unsuitable alluvium, however,for the purpose of this report, it has been estimated that the alluvium may extend to depths of 10t feet below existing ground surfaces. • Ouaternary Colluvium/fopsoil (no map symbol) — Quaternary colluvium and topsoil overlie the hillsides throughout the site and typically vary from approximately I to 3 feel deep. Colluvium/topsoil materials were observed to j consist of brown silly sand with abundant metasiltstone gravel and cobbles. The i RJH DEVELOPMENT January 11, 2001 �.; North Villa ge/remecula J.N- 461-00 Page I I soils were generally dry to damp and loose to medium dense. For mapping Purposes, colluvium/lopsoil materials in excess of 3 feet thick have been grouped with recent alluvial materials (Qal). • Oualemary Pauba Fanglomerale (map symbol Q120 — Fanglomerate deposits, which represent the younger unit of the Pauba Fonnation, were encountered or observed along the lower Banks of the foothills and adjacent to the Bedford Canyon Formation. The fanglomerate consists of fine to coarse-grained clayey to silty sandstone with a moderate quantity of melasilistone gravel and cobbles. The deposits were generally observed to be damp to moist and dense. • Jurassic Bedford Canyon Formation (map svmbol- Jbc) — Melasiltstone and sandstone of the Bedford Canyon Formation are located throughout the extreme western portion of site. This bedrock formation is generally highly weathered, dense to very dense and randomly foliated, jointed and fractured. Joints and fractures were noted to be 2 to 61- inches apart and to follow tluee conunon trends: an east-west set which was vertical to steeply; a northwest-trending set which dipped moderately to steeply dipping to the southwest; and a northeast-trending set which dipped moderately to steeply to the nortlnvest. t Groundwater Neither groundwaler nor seepage was encountered in any of the l orings or test pits excavated on the site by Pelra, Leighton, Soil Tech or GEE, at least to the maximum J 1 depth explored (43 feet). f# fe Faulting C• aThe geologic structure of the entire southern California area is dominated mainly by northwest-trending faults associated with the San Andreas system. Faults, such as the Newport-Inglewood, Whittier, Elsinore,San Jacinto and San Andreas, are major faults in this system and all are known to be active- In addition, the San Andreas, Elsinore and San Jacinto faults are known to have ruptured the ground surface in historic times. t a 1 3 .l U i RJH DEVELOPMENT January 11 , 2001 North Village/Temecula. J.N. 461-00 i Page 12 Based on our review of published and unpublished geoleclmical maps and literature pertaining to site and regional geology, the closest active faults to the site are the Wildomar branch of the Elsinore fault located approximately 0.5 mile to the east and I the San Jacinto fault located approximately 21 miles to the northeast. Based on studies by Leighton (1988), the Willard fault zone projects through the site at a location that closely correlates to the location mapped by Kennedy (1077). Leighton has concluded I That the Willard fault can be designated as Pre-Holocene or considered inactive by California State definition. Therefore, based on our studies, the most significant fault, with respect to anticipated ground motions,at the site, is the Wildomar branch of Elsinore fault, due to its proximity and possible large magnitude earthquake. Landslides I Landslide deposits were not encountered during our subsurface exploration and no I ancient landslides are known to exist on or near the site. i Flooding Potential ! Based on the Riverside County Seismic and Public Safety Element, the site is located within Zone C, which is designated as an area of minimal flooding. ` CONCLUSIONS AND RECOMMENDATIONS j General From a soils engineering and engineering geologic point of view, the subject property is considered suitable for the proposed development provided the following conclusions and recommendations are incorporated into the design criteria and project specifications. 1 RJII DEVELOPMENT January t I, 2001 North Village/remecula 1.N. 46 1-00 Page I ')Grading-Plan Review and Additional Exploration The recommendations presented in this repo^, are based on a review of H�z proposed grading shown on the enclosed 100-scale conceptual grading plan prepared by TKC ( I (Plate I)- Therefore, when definitive 40-scale grading plans have been prepared. Petra 1. should perform a detailed review of(he plans with respect to the geotechnical aspects of the proposed development. Depending on the results of the grading-plan review, 1 additional recommendations and/or modification of the recommendations presented herein may be necessary. Furthermore, additional subsurface exploration may be f warranted in the folloiving areas. L. When specific building locations are known, additional exploration should be performed within the two existing mass-graded level pads to accurately locate the transitions between cut and fill. • Additional seismic-refraction survey lines should be conducted in proposed deep- Cut areas to evaluate bedrock rippability and possible requirement for blasting. • Exploratory borings and/or backhoe test trenches should be excavated within the i'. larger canyons and tributary drainages to determine depths of unsuitable alluvial materials. Due to steep terrain, a bulldozer will be required to pioneer an access road for the exploratory equipment. Earthwork 4 General Earthwork and Grading Specifications J All earthwork and grading should be performed in accordance with the applicable requirements of the Grading Code of the County of Riverside. California, in addition to the provisions of the 1997 Uniform Building Code (UBC)Chapter Appendix A33. J Grading should also be performed in accordance with applicable provisions of the attached Standard Grading Specifications (Appendix D) prepared by Petra, unless specifically revised or amended herein. i U t RJR DEVELOPMENT January 11, 2001 North Village/Temecula 1.N- 461 -00 Paze 14 Clearing and Grubbing All trash and construction debris, weeds, brush, shrubs and trees should be stripped and removed from the site. Trees and large shrubs should be grubbed-out, such that their stumps and major root systems are also removed and the organic materials hauled offsite. During site grading, laborers should clear from fills any roots and other deleterious materials missed during clearing and grubbing operations. The project geotechnical.consultant should be notified at the appropriate limes to - provide observation services during clearing operations to verify compliance with the above reconunendations. In addition, should any buried structures or any i adverse soil or bedrock conditions be encountered during grading that are not described or anticipated herein, these condiiions'should be brought to the attention i of the geotechnical consultam for corrective reconunendations. Excavalion Characteristics and Bedrock Rippabilii Based on die exploratory borings and test pits, surficial soil deposits overlying bedrock (artificial fill deposits, alluvium and colluvium) are expected to be readily excavatable with conventional earthmoving equipment. Most bedrock materials (Pauba and Bedford Canyon Formations) should be excavatable with moderate to heavy ripping; however, localized areas of resistant bedrock can generally be anticipated in deep excavations in the Bedford Canyon Formation, conditions that may not entirely preclude the need for local blasting. The Bedford Canyon Formation consists of highly weathered and randomly fractured, jointed and foliated metasiltstone and ntetasandstone. Due to the jointing, this bedrock unit should be rippable with moderate difficulty; however, the bedrock becomes very dense and massive at depth_ When detailed grading plans are available, deep cut areas should t I v RJH DEVELOPMENT January 1 I, 2001 C North Village/Temecula 1.N. 461-00 Page 15 be reviewed and a seismic-refraction survey may be recommended to evaluate f bedrock rippability- l . Groundwater Groundwater is not expected to be encountered during grading operations; however, there may be a possibility that seepage will be encountered locally during removal �s t. of alluvium from canyons and tributaries. Ground Preparation - Fill Areas All existing low-density and potentially collapsible-soil materials, such as loose artificial fill, alluvium, colluvium and highly weathered bedrock, should be removed to underlying competent bedrock, dense native soils or existing compacted fill soils S r from each area to receive compacted fill. Dense native soils are generally defined !; as undisturbed native materials existing at an in-place relative compaction of 85 percent or.greater based on ASTM Test Method D1557-91, subject to verification by the project engineering geologist. Competent compacted fill soils are defined as l documented, engineered fill soils with an in-place relative compaction of 90 percent or greater. Prior to placing structural fills, the exposed bottom surfaces in each removal area should first be scarified to a depth of at least 6 inches, watered or air- dried as necessary to achieve near-optimum moisture conditions and then 't ' recompacted in-place to a minimum relative compaction of 90 percent. (? Based on test pits and borings and laboratory testing, anticipated depths of removals Lat each test pit and boring location are shown on the enclosed geotechnical map t' (Plate 1). However, actual depths and horizontal limits of removals will have to be determined during grading on the basis of in-grading observations and testing performed by the project geotechnical consultant. Furthermore, the depths of Fj alluvial removals indicated within the canyons and tributaries are based on an \/ i I JIM DEVELOPMENT January 11. 2001 i North Village/Temecula 1.N. 461-00 Pape 16 I anticipated condition and will require confirmation based on additional subsurface exploration or confirmation during grading. Canyon Subdrains Following clean outs to competent bedrock or approved native soils. canyon subdrains should be installed along the axes of all major canyons and tributary areas i where the depth of structural fill exceeds approximately 15 feet. Canyon subdrains will mitigate potential build-up of hydrostatic pressures below compacted fills due — to infiltration of surface waters or lateral seepage from the adjacent,bedrock. The , actual locations of the subdrains should be determined on the basis of a detailed grading plan review and on conditions encountered during grading. Typical canyon subdrain construction details are shown on Plate SG-4 (Appendix D). Disposal of Oversize Rock Excavations in bedrock will generate a moderate to locally significant amount of ! oversize rock (hard irreducible rock greater than 12:inches in maximum dimension). Oversize rock may be disposed of onsite by placing the rock in the lower portions of the deeper fills provided they are placed in a manner to avoid nesting. Rock greater than approximately 3 feet in maximum dimension should be placed individually with sufficient room between the rocks to allow for placement of fill and 1 compaction equipment. Rock less than 3 feet in maximum dimension may be placed in windrows and then completely covered with granular onsite soils. The granular in-fill materials should be thoroughly watered and wheel-rolled to ensure closure of iall voids. A typical rock disposal detail is shown on Plate SG-2 (Appendix D). t i 1 . RJH DEVELOPMENT January 11. 2001 North V ilia ge/f-emecula J.N. 461-00 f Page 17 L, Fill Placement All fill should be placed in 6- to 8-inch-thick-maximum lifts, watered or air-dried as necessary to achieve near-optimum moisture conditions and then compacted in- place to a minimum relative density of 90 percent. The laboratory maximum dry density and optimum moisture content for each change in soil type should be determined in accordance with ASTM Test Method D1557-91. Benching Compacted fills placed against canyon walls and on natural-slope surfaces inclining at 5:1 (h:v) or greater should be placed on a.series of level benches excavated into competent bedrock or dense native soils. Typical benching details are shown on Plates SG-3, SGA. SG-5. SG-7 and SG-8 (Appendix D). I Processing of Cut Area,; r' Where existing low-density surficial soils are exposed at finish grade in cut areas, 1e. the unsuitable soils should be removed and replaced as properly compacted fill. The removals should extend to competent unweathered bedrock, dense native soils or competent previously compacted fill soils. Overexcavation of Cut Lots and Cut Streets in Bedrock Areas Backhoes and wheel-trenchers may experience a moderate to locally very high Y degree of difficulty when excavating footing and utility trenches in resistant bedrock materials exposed at finish grade. Therefore, in order to facilitate excavation of footing trenches, it is recommended that cut lots exposing hard, resistant bedrock be overexcavated to a depth of 3 feet below finish grades and then capped with T compacted fill. For similar reasons, streets should be overexcavated to the depth of s the deepest utility and then brought back to grade with compacted fill_ 1 U t 1 RJH DEVELOPMENT January 11, 2001 North Village/Temecula J.N. 46 1-00 Page 13 i Cut/Fill Transition Lots i To mitigate cislr,:s, to buildings related tc the potential -dverse effects of differential settlement, cut/fill transitions should be eliminated from building sites where the dc;;th of fill placed within the "fill" portion exceeds proposei fooling deltas. This should be accomplished by overexcavating the "cut" portion and replacing the overexcavaled materials as properly compacted fill. Recommended minimum depths i of overexcavation are provided in the following table. i Depth of fill - `Fill'.' Portion Depth of.Overexravalion - "Cut" Portion Up to 5 feet Equal depth (3 feel minimum) Greater than 5 feet One-half the thickness of till placed on the `Fill" portion 1 (15 feet maximum) Horizontal limits of overexcavation should extend beyond perimeter-building lines a distance equal to the depth of overexcavation or to a minimum distance of 5 feet, whichever is ereater. Shallow-Fill to Deep-Fill Lots To mitigate distress to buildings related to the potential adverse effects of excessive differential settlement on building sites underlain with substantial differences in compacted fill depths, the "shallow" fill portions should be overexcavaled to maintain the minimum fill depths recommended in the preceding table. Cut Slopes 1 Proposed Cut Slope Construction — A series of 1 .5:1 (h:v) cut slopes are proposed along both sides of the Western Bypass Corridor to vertical heights varying from approximately 20 to 125 feet. A majority of the proposed 1.5A (h:v) cut slopes will be excavated in the Bedford Canyon Formation while the i U. �I RJH DEVELOPMENT January It. 2001 North V illager remecula J-N. 461-00 Page 19 others will locally be excavated in Pauba fanglomerate. Cut slopes bordering the proposed commercial building pads are planned at a slope ratio of 2: 1 (h:v) and to vertical heights varying from approximately 20 to 40 feet. A majority of the 2:1 (It:v) cut slopes will be excavated in existing compacted till deposits and the others in Pauba fanglomerate. • Cut Slope Stabiles — The majority of the proposed cut slopes will be excavated in the metasedimentary Bedford Canyon Formation while the remainder will 111{ locally be excavated in the Pauba fanglomerate or in existing compacted fill i materials. The foliation, joint and fracture trends in the Bedford Canyon Formation are discontinuous and randomly oriented and were observed to be multi-directional and to dip at angles generally steeper than approximately 50 degrees. Therefore, it is expected that cut slopes excavated at slope ratios of 1 .5: 1 (h:v) and 2: 1 (h:v) within the Bedford Canyon Formation will expose foliation, joint and fracture trends that are favorably oriented and the slopes are not expected to be subject to a translational, block-glide or deep-seated circular- type failure. As such,cut slopes excavated in the Bedford Canyon Formation are expected to be grossly stable; however, vi in-grading obserx ition of individual cut slopes should be performed by the project engineering geologist to conftnm favorable geologic structure of the exposed bedrock. Should out-of-slope foliation,joint or fracture trends be observed, the cut slopes in question may be subject to local block-glide failures and require stabilization by means of a compacted buttress fill or stabilization fill. The Pauba fanglomerate is generally massive and typically does not exhibit any adverse bedding or well-defined planes of weakness. Therefore, cut slopes s excavated within this bedrock unit are also expected to be grossly stable; ' however, an in-grading observation of individual cut slopes should also be l performed by the project engineering geologist to confirm favorable geologic structure of the exposed bedrock. Should out-of-slope bedding, seepage or uncemented sand strata be observed, the cut slopes in question may require ei stabilization by means of a compacted buttress fill or stabilization fill. - Slope Stability Calculations — To further evaluate the gross stability of the proposed cut slopes for the most critical slope condition, Cross-Section A-A' (Figure 2) was prepared to show the highest 1 .5A (h:v) cut slope condition proposed along both sides of the Western Bypass Corridor. This slope condition consists of an ascending 125-foot-high cut slope on the west side of the Western Bypass Corridor that will be excavated in the Bedford Canyon Formation and a descending 90-fool-high cut slope on the east side that will be excavated in both the Pauba fanglomerate and the Bedford Canyon Formation. Stability i RM DEVELOPD4ENT January 11, 2001 North Village/hemecula J.N. 461-00 Page 26 Seismic Design Considerations I Ground Motions I Siructures within The site should be designed and constructed to resist the effects of seismic ground motions as provided in 1997 UBC Sections 1626 through 1633. The method of design is dependent on the seismic zoning, site characteristics, occupancy category, building configuration, type of sfrucmral system and building height. Note that a site-specific geoingictseismic report will be required for the'proposed school site to be.submitted to the Division of the,State Architect in compliance with the California Code of Regulations. Title 24. i Seismic_design coefficients were determined using UBCSEIS, a computer program developed. by Thomas F .Blake (UBCSEIS. 1998). This program compiles fault information for a particular site using a modified version of a data file of 183 California faults that were digitized by the Califomia Depaitmeni of Mines and Geoloey ant.the U.S_ Geological Survey. Various,data'are.compmed for a particular site, including the distance of the site from each of the faults in the data file, the: estimated slip-rate for each fault and the"maximum moment magnitude' of each fault. The program then selects the closest Type A, Type B and Type C faults from the site and computes The seismic design coefficients for each of the fault types. The highest t 1 computed seismic design coefficients are then selected as the design coefficients for the subject site. Based on the computer analysis, the Wildomar fault of the Elsinore fault zone(located 1 Tess than 1 kilometer from the site) would probably generate the most severe site ground motions with an anticipated maximum moment magnitudes of 6.8 and i anticipated slip rate of 5.0 mm/year. The following 1997 UBC seismic design coefficients have been determined for this fault and are recommended for use in the t 3, j RJII DEVELOPMENT January it . 2001 North VillagefTemecula 1.N. 461-00 Page 27 C. design of the proposed structures- These seismic design coefficients are based on the soil-profile type as determined by existing subsurface geologic conditions, the C proximity of the site to the 1Vildomar fault and on the maximum moment magnitude and slip rate of the nearby fault. Parameters for structures founded directly on bedrock or full materials are presented in the following tables. 4r Structures Founded on Bedrock UBG 1997 TABLE FACTOR 16.1 Seismic Zone Factor Z 040 C16-1-1 Seismic Source Tvpc B 'i 164 Soil Profile S n 16-5 Near Source Factor N, I.i r 16-T Near-Source Factor N. 1.6 f 16.Q Seisinic Coefficicm C, 0 ION, =0 ?2 16-R Seismic Coefficient C, 0 40N. =0.61 C_ i Structures Founded on Dense Soil IPaubal or Enpineered Fill UBC 1997 TABLE. . FACTOR _ 16-1 Seismic Zone Factor Z OAO �3 16-U Seismic Source Type B 16A Soil Profile Type So 1 16.5 Near-Source Factor N. 1.3 r i- 16-T Near-Source Factor N. 1.6 16.Q Seismic Coefficient C. 0.44N, =0.57 16-R Seismic coefficient C, 0 64N,= 1,02 c-a {fFii A: 4 i l t RJH DEVELOPIWENT January I i, 2001 North Village/Temecula I.N. 46 1-00 I Page 2S i Secondary Effects of Seismic Activity i Secondary effects of seismic 1:'ti-jity norrr::ll., -onsidrred a p. ,sible hazards to a site include several types of ground failure and induced flooding. The general types ground failures tha� can occur a.. a cons^quence of severe ground shaking at a Sits Iinclude landsliding, ground subsidence, ground lurching, shallow ground rupture and liquefaction. The probability of occurrence of each type of ground failure depends upon seve;af factors, including the severity of the earthquake, distance from faults, topography and subsurface soil and groundwater conditions, as well as other ! less significant factors. Based on our seismic evaluation of the site. all of the above secondary effects of seismic activity are considered unlikely a(the site. ( Active faulting was not observed on the site: therefore. the potential for ground j I lurching or shallow ground rupture is considered very low. The potential for earthquake-induced liquefaction within die site is considered very low to remote due to the dense nature of onsite soils and the absence of groundwater I ` j within at least the upper 43 feet. Seismically induced flooding which might be considered a potential hazard to a site t normally includes flooding due to a tsunamis (seismic sea wave), a seiche (i.e., a t wave-like oscillation of the surface of water in an enclosed basin that may be 1 initiated by a strong earthquake) or failure of a major reservoir or retention structure ' t upstream of the site. Since the site is located nearly 25 miles inland front the nearest coastline of the Pacific Ocean at an elevation in excess of 1 .000 feet above mean sea level, the potential for seismically induced flooding due to a tsunamis run- up is considered nonexistent. Furthermore, due to.the absence of nearby impounded surface waters, seismic related flooding is considered to be remote_ i fi I r l : F RJH DEVELOPMENT January 1 I, 2001 North Village[Temecula J.N. 461-00 Page 29 f Tentative Foundation-Design Recommendations r� General t Provided site grading is performed in accordance with the recommendations of this i;• report, conventional shallow foundations are considered feasible for support of the proposed structures. Tentative foundation recommendations are provided herein. However, these recommendations may require modification depending on as-graded conditions existing within the building sites upon completion of grading. L : ffAllowable-Bearing Values l: • Footings Founded in Compacted Fill — An allowable-bearing value of 1 .500 f per square foot pounds p q (psf) may be used for design of 24-inch-square pad footines and 12-inch-wide continuous footings founded in compacted fill and at a minimum depth of 12 inches below the lowest adjacent final grade. This value ` may be increased by 20 percent for each additional foot of %vidttt and depth, to L a maximum value of 2,500 psf. Recommended allowable-bearing values include both dead and live loads and may be increased by one-third for short-duration t wind and seismic forces. I 1 Footings Founded in Competent Bedrock — An allowable-bearing value of 2,500 psf may be used for design of 24-inch-square pad footings and 12-inch-wide continuous footings founded in competent bedrock and at a minimum depth of 12 [t, inches below the lowest adjacent final grade. This value may be increased by 20 � percent for each additional foot of width or depth, to a maximum value of 4.000 psf. Recommended allowable-bearing values include both dead and live loads and t may be increased by one-third for short-duration wind and seismic forces. f Settlement l� ti Based on the general settlement characteristics of compacted fill soils and in-situ if bedrock, as well as the anticipated loading, it has been estimated that the maximum . total settlement of conventional footings founded in compacted fill will be less than approximately 0.75 inches. Differential settlement is expected to be about one-half f i U i RJH DEVELOPMENT January 11 , 2001 North Village/Temecula J.N. 461-00 Page 30 the total settlement or approximately 0.5 inches over a horizontal distance of 40 feet. For footings founded in competent bedrock, it is estimated that maximum total and j differential settlements will be approximately one-half to txvo-thirds of the above I estimated settlements of footings founded in compacted fill. It is fitrther anticipated that the majority of footing settlements will occur during construction or shortly thereafter as building loads are applied. I Lateral Resistance • Footings Founded in Compacted Fill — A passive earth pressure of 250 psf per foot of depth to maximum.value of 2,500 psf may be used to determine lateral- j bearing resistance for footings founded in compacted fill- However, where i footings are founded on slope surfaces or near the tops of descending slopes, a passive earth pressure of ISO psf per foot of depth to a maximum value o f 1 ,500 psf should be used for design. In addition to passive ;earth pressures, a ! coefficient of friction-of 0.4 limes the dead-load forces may be used between concrete and the supporting,soils to determine laieral slidirtr; resistance. The i above values may be increased by one-third�ivlien designing for short-duration wind or seismic forces. The above values are based on footings placed directly t against compacted.fill. In the case where footing sides are formed. all backfill I placed against, the footings should be compacted to in least 90 percent of maximum d:y density. iFootings Founded in Competent Bedrock — A passive earth pressure of 400 psf per foot of depth to a maximum value of 4.000 psf may be used to determine lateral-bearing resigtance for footings founded in competent bedrock. However, I where footings are founded on slope surfaces or near the tops of descending slopes, a passive earth pressure of 250 psf per foot of depth to a maximum value of 2,500 psf should be used for design. In addition to the recommended passive ` earth pressures, a coefficient of friction of 0.4 times the dead-load forces may be used between concrete and the suppordng.bedrock to determine lateral sliding resistance. The above values may be increased by one-di ird when designing for short-duration wind or seismic forces. I 1+ RJH DEVELOPMENT Januar: 11. 2001 North VillagefTemecula J.N. 461-00 Pape 31 CFooling Setbacks From Descending Slopes Wher^ buildings are proposed on or near the tops of descending slopes, the fooling setbacks from the slope face should conform with 1997 UBC Figure 18-1-1 . The required minimum setback is H13 (one-third the slope height) measured along a horizontal line projected from llte lower outside face of the footing to the slope face. The footing setbacks should be 5 feet minimum where the slope height is 15 feet or less and vary up to 40 feel maximum where the slope height exceeds 15 feet. -Where buildings structures are proposed near the tops of descendine cut slopes composed of sound bedrock materials, the fooling setbacks from the slope face should also generally conform with 1997 UBC Figure 18-1-1 ; however, the maximum footing setback may be reduced to 15 feet in-lieu of 40 feet where the slope height exceeds 15 feet. C Building Clearances From Ascending Slopes Building setbacks from ascending cut and fill slopes should conform with 1997 UBC Figure 18-1-1 that requires a building clearance of H/2 (one-half the slope height) varying from 5 feel minimum to 15 feet maximum. The building clearance is measured along a horizontal line projected from the toe of the slope to the face of the building. A retaining wall may be constructed at the base of the slope to achieve the required building clearance. Fooling Observations All building-footing trenches should be observed by the project geotechnical L; consultant to verify that they have been excavated into competent-bearing soils- The foundation excavations should be observed prior to the placement of forms, reinforcement or concrete. The excavations should be trimmed neat, level and t 1" U i RJ11 DEVELOPMENT January 1 I . 2001 North Village/Temecula J.N. 461-00 Page 36 penetrate to a minimum depth of 12 inches and maintained in the subgrade during concrete placement to promote uniform curing of the concrete and minimize the development of shrinkage cracks. Retaining Walls I t Allowable Bearing Values and Lateral Resistance jFootings for retaining walls may bedesigned using the allowable bearing and lateral resistance values recommended for building footings, including:a reduction in the 1. _passive earth pressure for footings founded on or near the tops of descending slopes. f i Footing Embedments i The base of retaining-wall footings constructed on level ground may be founded at a minimum depth of '12 inches below the lowest adjacent final grade. However, where retaining walls. are proposed on.or within 15 feer from if e'iop of any adjacent descending fill slope, the: footings should be deepened such that a minimum 1 horizontal clearance of 15 feet is maintained between the outside bottom edges of the footings and the face of the slope. This horizontal structural setback may be reduced j to 10 feet where footings are constructed near the tops of descending cut slopes. The above recommended minimum footing setbacks are preliminary and may require revision based on site-specific soil and/or bedrock conditions. All footing trenches i should be observed by the project geotechnical representative to verify that the footing trenches have been excavated into competent-bearing soils and/or bedrock and to the minimum embedments recommended above. These observations should be performed prior to placing forms or reinforcing steel. I I 1 � k`r1 l R.111 DEVELOPMENT January 1 1, 2001 r North VillagelTemecula 1.N. 461-00 Page 37 L Active and At-Rest Earth Pressures An active lateral-earth pressure equivalent to a fluid having a density of 35 pounds per cubic foot (pcf) should tentatively be used for design of cantilevered walls retaining a drained, level backftll. Where the wall backfill slopes upward at 2:1 f. (h:v) or 1.5: 1 (h:v), the above value should be increased to 52 and 65 pcf, respectively. All retaining walls should be designed to resist any surcharge loads r impoced by other nearby -nails or structures in addition to the above active c:lrth ' I pressures. For design of retaining walls that are restrained at the top, an at-rest earth pressure equivalent to a fluid having a density of 53 pcf should tentatively be used for walls n supporting a level backftll. This value should be increased to 73 and 95 pcf for an ascending 2: 1 (h:v) and 1.5: 1 (h:v) backftll, respectively. Drainage 1eepholes or open vertical masonry joints should be provided in retaining walls to f prevent entrapment of water in the backfill. weepholes, if used, should be 3 incites in minimum diameter and provided at minimum intervals of 6 feet along the wall. i' "t Open vertical masonry joints, if used, should be provided at 32-inch-minimum intervals. A continuous gravel fill, 12 inches by 12 inches, should be placed behind I the weepholes or open masonry joints. The gravel should be wrapped in filter fabric to prevent infiltration of fines and subsequent clogging of the gravel. Filter fabric may consist of Miraft 140N or equal. In lieu of weepholes or open joints, a perforated pipe-and-gravel subdrain may be J used. Perforated pipe should consist of 4-inch-minimum diameter PVC Schedule 40 or ABS SDR-35, with the perforations laid down. The pipe should be embedded in J 'i W . i i RJH DEVELOPMENT January 11 , 2001 North Village/Temecula 1.N. 461-00 i Page 38 1 .5 cubic feet per foot of 0.75- or 1.5-inch open-graded gravel wrapped in filter fabric- Filter fabric may consist of Nfiraft 140N or equal. The backfilled side of retaining walls should be coated with, an approved v :iierproofing compound to inhibit infiltration of moisture through the walls- TernpQrary Excavations i I To facilitate retaining wall construction, the lower 5 feet of temporary slopes may be cut vertical and the upper portions exceeding,a height of.5 feet should be cut back at a maximum gradient of 1: 1 (h:v) for the duration of consuvction. However, all temporary slopes should be observed,by the project soils engineer for any evidence of potential instability. Depending on the results of these observations, nailer slopes may be necessary. The potential effects of various parameters such as weather, heavy equipment travel, storage near the tops of the temporary excavations and i construction scheduling should also be considered in the, stability of temporary slopes. Wall Backfill All retaining-wall backfill should be placed in 6- to 8-incli-maximum lifts, watered or air-dried as necessary to achieve near-optimum moisture conditions and compacted in place to a minimum relative compaction of 90 percent. i I ' Cement Tvoe Soluble-Sulfale Analyses Laboratory test data indicate site soils contain less than 0. 1 percent water-soluble I sulfates, Therefore, according to 1997 UBC Table 26-A-6, Type 1 or 11 cement will be appropriate for concrete to be placed in contact with onsite soils. I � t v RJH DEVELOPMENT January 11, 2001 North Village/Temecula 1.N. 461-00 Page 39 GRADING-PLAN REVIEW AND CONSTRUCTION SERVICES This report has been prepared for the exclusive use of R1H Development to assist the project engineer and architect in the design of the proposed development. It is r recommended that Pelra be engaged to review the final-design drawings and f.: specifications prior to construction. This is to verify that the recommendations contained in this report have been properly interpreted and are incorporated into the =J project specifications. If Petra is not accorded the opportunity to review these Y documents, we can take no responsibility for misinterpretation of our frecommendations. L� i We recommend that Petra be retained to provide soil-engineering services during t construction of the excavation and foundation phases of the work. This is to observe compliance with the design, specifications or recommendations and to allow design changes in the event that subsurface conditions differ from those anticipated prior ..d r: to start of construction- If the project plans change significantly, we should be retained to review our f= t ' original design recommendations and their applicability to the revised construction. :i <� If conditions are encountered during construction that appear to be different than U those indicated in this report, this office should be notified immediately. Design and .t. r, construction revisions may be required. i � lai R3. INVESTIGATION LIMITATIONS �3 This report is based on the project, as described and [fie geotechnical data obtained from the field tests performed at the locations indicated on the plan. The materials y encountered on the project site and utilized in our laboratory investigation are u I rsl i4 RJH DEVELOPMENT January 11, 2001 North Villagerremecula J.f!. 461-00 Page 40 believed representative of the total area. However, soils can vary in characteristics j between excavations, both laterally and vertically- The conclusions and opinions contained in this report are based on the results,of the described geotechnical evaluatiops and.d rprr.;ent o!tr best profc.:.'OtW judgement. The findings, conclusions and opinions contained in this report are to be considered tentative only and subject to confirmation by the undersigned during the construction i process. Without.this confirmation, this report is to, be considered incomplete and Petra or the undersigned professionals assume no responsibility for its use. In addition• this report should be re"viewed and updated after•a period of I year or if the site ownership or project concept-changes from that described herein. I This report has not been prepared for use by parties or projects other than those i named or described above. It may not contain sufficient information for other parties or other purposes. The professional opinions contained herein.have been derived 'in accordance With current standards of practice and no warranty is expressed or implied. Respectfully submitted, QRpF ESSrON ! PETRA GEOTECHNICAL, INC. �o otA R. W 4t. �aGtNEEA/N� k 4�F� �O G. 6EgG, Q / •. l �. �� w v tio.871 f— ,cc z ergmann Gra son R. Walke EXP. �; c� EX o. 1348 n v, I Geologist Senior Associate E tin P� * 48 GE 871 Jj, nP RrFOr CAl1FOF 9�pC/+i /CBIGRW/MBfkeb i 1 1 A Al IDO 1100 • PROPOSED WESTERN BYPASS CORRIDOR 1700 // \ � / \ / / .1700 PROPOSED I S CUT SLOPE PROPOSED '41 EXISTING IS CUT GLOVE --� 1700w g GROUND SURFACE I \ / // \ Ool / 9 �'� w n00 nurn I /�_____ i /1 / I \ \ J0c II / I100 w loon \� \/ 1000 NO 900 (POSTULATED FAULT LOCATIONS,XENNEDY.1977) I B BI C ❑00 L•/ 1••I1700 MO �I -t700 E%ISTING PROPOSED WESTERN GROUND PROPOSED WESTERN BYPASS CORRIDOR SURFACE BYPASS CORRIDOR EAISTINO w 1700 � RND1700 1}DO PROPOSED 21 �/^ \ / I ♦< ,W. /---'�\ SURFACE M0 w 3 PB,I SLOPE \ / I \ / I 2 3 PM1L SLOP6` ROPOSED E.1 / EXISTING CUT SLOPE / \ / I SOPSWITH EXISTING CUT F WITH DRAIN AT TOP / SLOPE // O TERRACE DRAW/ W II W / I / I /\ I \ I \ •1100 W W 1100 1100 \ / I \ Ja \ CROSS SECTIONS A-A', 6-13'.AND C-C' \� / \ / \ I PETRA GECTECHNICAL. INC. s<.11 1000 1000 1000 0 100 F:H JN.BI.00 JAN 3001 (HORIZONTAL E VERTICJLI FIGURE 2 t 11y'�\ 1 off G +?. • .. ..� -.r. ,00� n - � `-�ji1 •Ran•� - 0� \ ', 1` /�.•�_ 4"�l r ��i-� \: Caldo." \ Y�' ,.� .;[�1`1• i• �.- •'. ' � Fyn \�. —��\I C--.• -\ J/ .1 \l? •/�7 c—n�`!a`J\ 'b F S"�� r'4 . /= r. 1 1 1/ ` o 1 l� e• _ 1 - � .aae-•: Lau 1 ', 1,:�.�� / "J 1�`� /�C �]5..; �. .`f ^,\ vT ,vtir�ac LOCATT �.- - SITE;.' ��''� -, .�" � � , ��:• i \t_• tip. . ' . . \ .S \ ry♦ Y' `/ r /. ':--••^ J -t •mil I. SITE LOCATION MAP I REFERENCE � PETRA GEOTECHNICAL. INC. : U STATE OF CALIFORNIA SPECIAL NORTH STUi TEMDIES ZONE ECULA QUAD MAP SERIES. O 2000 FEET JN 461-00 JAN 2001 w MURRIETA QUAD 1/1/90 J N SCALE FIGURE 1 REFERENCES Blake, 1998c,- UBCSEIS, Version 1,30. A Computer Program for the Estimation of Uniform Building Code Coefficients Using 3-D Fault Sources.- [. Campbell K.W. and Bozorgnia. Y.. 1994, -Near Source Attenuation of Peak Horizontal .Acceleration from Worldwide Acceferograms Recorded from 1957 io 1993:-Proceedinesof the Filth U.S_ National Conleretrre on Earthquake Engineering. Vol Ill. Earthquake Engineering Institute. pp. 283-292. Campbell, K-W. 1997 "Empiracal Near-Source Attenuation Relationships for Horizontal and Vertical Components of Peak Ground Acceleration, Peak Ground Velocity and Pseudo-Absoluie Acceleration Response Spectra," Seismnloeical Research Letters. Vol. 68, No. I, pp.154-179. i Envicom and County of Riverside Planning Department, 1976. County of Riverside Seismic Safety and Safety Elements. September 1976. " Geotechnical & Environmental Engineers. Inc., 1996. Preliminary Geofechnical Investigation. Proposed Western Fr Bypass Corridor Project From Rancho California Road to State Highway 79 South and Vincent Moraga Drive Extension, City of Temecula, California, Work Order No. 324502.00, dated January 10. E, Geotek. 1981, Evaluation of Liquefaction Potential, Lot 3 and Portions of Lots 2 and a of Block 36. Temecula. Riverside County, California. P.N. 8S3WRC-13. dated September 21. 1981. ' Giessner. F.%V-; Winters. B.A-; and McLean.J.S.. 1971. Water Wells and Sprmgs in the tk0stern Part of the Upper Santa Margarita River Watershed. Riverside and San Diego Counties. California, State of California Department of Water Resources Bulletin 91-20. - International Conference of Building Officials, 1997. Uniform Buildine Code, Structural Eneinecnne Design Provisions. - . 1998. Maps of Known Anise Fault Near-Source Zones in California and Adjacent Portions of Nevada. rPrepared by California Division of Mines and Geology. i Jenkins. Olaf P., 1966. Geologic Map of California. Santa Ana Sheet. Scale: 1:250.000. Jennings, C.W., 1962, Geologic Map of California, Olaf P. Jenkins Edition. Long Beach Sheet, Scale 1:250.000. 'i 1985. An Explanatory Text to Accompany the 1:750.000 scale Fault and Geologic Maps of California. California Division of Mines and Geology. 1994, Fault Activity Map of California and Adjacent Areas, Scale 1:750.000. _ Kennedy, M.P., 1977, Recency and Character of Faulting Along the Elsinore Fault Zone in Southern Riverside County, California, CDMG Special Report 131. Leighton and Associates. Inc., 1988. Reliminary Geotechnical Investigation for Parcels 18. 20. 21, 23. 24. 25. 26. 27, 28 and 29of Parcel Map 18254, Rancho California, Riverside County, California, P.N. 11881191-01, dated October 24. 1988. I PETRA GEOTECHNICAL, INC. JANUARY 2001 r! J.N. 461-00 i =. �F REFERENCES (Continued) 1988. Addendum Report - Response to County of Riverside Review Letter dated December 14• 193S regarding General Plan Amendment 137. Rancho California, Riverside County. California, Project No. 11881191-01. dated December 29. 1938. 1989. Response to County of Riverside Review Letter dated January 9. 1989 regarding General Plan Amendment 137, Rancho California. Riverside County, California, Project No. 1 1831 191-01, dated January 24, 1989. i Mann, J-F., 1955. Geology of a Portion of the Elsinore Fault Zone, Division of Mines Special Report 43. dated October 1955. Pioneer Consultants, 1975. Soil and Geologic Invesngavon, Proposed bdustrial Park Expansion, Rancho California. J.N. 1208.095. dated March 21. 1975. Soil Tech, Inc..1989.Geolechnical Testing, Grading Report Parcels Ithrough 3 of Parcel Map 19626-I. Parcel 1 of Parcel Map 19626.2. Project Number 2980-C-89, dated April 12. 1989. 1989. Preliminary Geotechnical Investigation, Parcel 22 of Parcel Map 18254. Project Number 3074-PS- j 89, dated May I. 1989. 1989, Geotechnical Testing. Grading Report, Parcel Map 19626-2. Project Number 2980-C-89. dated October 2. 1989. State of California Department of Water Resources, 1966, Hydrologic Data: 1964. Volume V: Southern California, 1 Appendix C: Groundwater Aleasurements, Bulletin No. 130.64. July. 1966. 1973. Hydrologic Data: 1972• Volume V: Southern California. Bulletin No. 130-72. November 1973. i State of California Special Studies Zones. AJurrieta Quadrangle. Scale 1:24,000, dated January 1, 1990. Temecula Quadrangle. Scale 1:24.000. dated January 1. 1990. Weber, F.H., Jr., 1977• Seismic Hazards Related to Geologic Factors, Elsinore and Chino Fault Zones. Northwesters Riverside County, Cahl'ornia, CDMG Open File Report 77.4 LA, May 1977. i i 1 Aerial-Photos Revievved Dale` Phol0Number s, 'kale L ttich.= 01/28/62 14/I S 7.000 .. • 11/27/83 199/200 1.600 02/03/95 19-12/14 I.600 04/25/00 19.12/13/14 1.600 PETRA GEOTECHNICAL, INC JANUARY 2001 j.N. 461-00 t � r s i