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Home My WebLink About06-3409 (MFD5) Addendum to Geotechnical Reportt a Earth Systems Southwest August 14,2006 Coachella Valley Housing Coalition 45-701 Monroe Street, Plaza l, Suite G Indio, Californi a 92201 Subject: Project: Ciry OF LAQUINTA BUILDING & SAFETY DEPT. APPROVED FOR CONSTRU CTION 79-81lB Country Club Drive Bermuda Dunes, CA92203 (760) 345-1588 (800) 924-701s FAX (760) 345-731s le No.: 09571-04 06-08-778 )AT lrfi #fl\>\ Attention: Mr. Steve Crowell Addendum to Geotechnical Engineering Report Proposed Multi-Family Residential Development Northwest Corner of Dune Palms Road and Avenue 48 La Quinta, California sEP 2u ztst \ \t;- Referense:Earth Systems Southwest, Geotechnical Engineering Report, Proposed Multi- Family Residential Development, Northwest Corner of Dune Palms Road and Avenue 48,La Quinta, California, File No.: 09571-04, Document No.: 06-07-734, dated July 13,2006. Dear Mr. Crowell: As requested by Mr. George Grayner, we present this addendum to the referenced geotechnical engineering report prepared for the proposed multi-family residential development to be located on the northrvest corner of Dune Palms Road and Avenue 48 in the City of La Quinta, California. We understand that a three-story concrete parking structure with basement is planned. The maximum column load is 350 kips and the maximum wall loading is 5 kips per linear foot-for thisparkingstructure.T6effincedgeotechnicalengineeringrepo@her buildings and the following grading and foundation recommendations are applicable for this parking structure. Grading Recommendations Soils within the zone of influence include silty sands and sands. Due to this relatively non- uniform and variable subsurface condition, we recommend over-excavation and recompaction of soils in the building area to provide a uniform bearing layer below the footings. The existing surface soils within the building pad and foundation areas should be over-excavated to a minimum of 5 feet below the footing level. The over-excavation should extend for at least l0 feet beyond the outer edge of exterior footings. The bottom of the sub-excavation should be scarified, moisture conditioned to near optimum, and recompacted to at least 95% relative compaction (ASTM D 1557) for an additional depth of I foot. Engineered Fill Soils: The native sandy soil is suitable for use as engineered fill and utility trench backfill, provided it is free of significant organic or deleterious matter. The native soil I N I August 14,2006 File No.: 0957 t-04 06-08-778 should be placed in maximum 8-inch lifts (loose) and compacted to at least 95% relative compaction (ASTM D 1557) near its optimum moisture content. Compaction should be verified by testing. Imported fill soils (if needed) should be non-expansive, granular soils meeting the USCS classifications of SM, SP-SM, or SW-SM with a maximum rock size of 3 inches and 5 to 35Yo passing the No. 200 sieve. The geotechnical engineer should evaluate the import fill soils before hauling to the site. However, because of the potential variations within the borrow source, import soil will not be pre-qualified by ESSW. The imported fill should be placed in lifts no greater than 8 inches in loose thickness and compacted to at least 90% relative compaction (ASTM D 1557) near optimum moisture content. Foundation Design Recommendations tuFooting design of widths, depths, and reinforcing are the responsibility of the Structural Engineer, considering the structural loading and the geotechnical parameters given in this report. A representative of ESSW should observe foundation excavations before placement of reinforcing steel or concrete. Loose soil or construction debris should be removed from footing excavations before placement of concrete. i/A summary of our design recommendations for spread foundations for columns are as follows: Excavations and Utility Trenches Excavations should be made in accordance with CaIOSHA requirements. Our site exploration and knowledge of the general area indicates there is a potential for caving of site excavations (utilities, footings, etc.). Excavations within sandy soil should be kept moist, but not saturated, to reduce the potential of caving or sloughing. Where excavations over 4 feet deep are planned, lateral bracing or appropriate cut slopes of 1.5:l (horizontal:vertical) should be provided. No surcharge loads from stockpiled soils or construction materials should be allowed within a horizontal distance measured from the top of the excavation slope and equal to the depth of the excavation. Utilitlz Trenches: Backfill of utilities within roads or public right-of-ways should be placed in conformance with the requirements of the governing agency (water district, public works department, etc.). Utility trench backfill within private property should be placed in conformance with the provisions of this report. In general, service lines extending inside of properfy may be backfilled with native soils compacted to a minimum of 90Yo relative compaction. Backfill operations should be observed and tested to monitor compliance with these recommendations. EARTH SYSTEMS SOUTHWEST 2 Anticipated Total Static Settlement Estimated Differentia I Sefflement Design Column Load Allowable Bearing Pressure Minimum Footing Size 9.5ftx9.5ft I inch 0.5 inch350 kips 4000 psf I August 14,2006 3 File No.: 09571-04 06-08-778 We appreciate the opportunity to provide our professional services. Please contact our office if there are any questions or comments concerning this report or its recommendations. Respectfu lly submitted, EARTH SYSTEMS SOUTHWEST Reviewed by, )M-, r,cE4s3 Senior Vice-President Hongbin uo, Ph.D. Project Engineer SER/hh/lk/ajf Distribution:3/Coachella Valley Housing l/RC File 2/BD File N0. c{25801 K No. GE 4e3 Ext o \\HC KL s * l{J &, oF 691-\( * ESS/ EARTH SYSTEMS SOUTHWEST il,.- t COACHELLA VALLEY HOUSING COALITION 45-7OI MONROE STREET, PLAZA I, SUITE G INDIO, CA[,IFORNIA 9220 I GEOTECHNICAL ENGINEERING REPORT PROPOSED M ULTI-F'AMI LY RESIDENTIAL DEVELOPMENT NORTHWEST CORNER OF' DUNE PALMS ROAD AND AVENUE 48 LA QUINTA, CALIFORNIA July 13,2006 O 2006 Earth Systems Southwest Unauthorized use or copying of this document is strictly prohibited without the express written consent of Earth Systems Southwest. File No. : A9571-04 06-07 -734 e Earth Systems Southwest 79-81 I B Country Club Drive IJernruda Dunes, CA 92203 (760) 34s- I 588 (800) e24-70t5 FAX (760) 345-73ts July I 3,2006 File No. : 09571-04 06-07 -734 Coachella Valley Ilousing Coalition 45-701 Monroe Street, Plaza l, Suite G Indio, Californi a 92201 Attention: Mr. Steve Crowell Subject: Geotechnical Enginecring Report Project: Proposed Multi-Family Residential Development Northwest corner of Dune Palms Road and Avenue 48 La Quinta, California Dear Mr. Crowell: We take pleasure in presenting this geotechnical engineering reporl prepared for the proposed multi-family residential development to be located on the northwest corner of the intersection of Dunc Palms Road and Avcnue 48 in thc City of La Quinta, Calilbrnia. This report prescnts our findings and recommendations for site grading and foundation design, incorporating the informatiott providcd to our office. The site is suitable for the proposed developmcnt, provided the recommendations in this report are followed in design and construction. In gcncral, the uppcr soils should be compacted to improve bearing capacity and reduce the potential for differential settlement. The site is subject to strong ground motion from regional faults, including the San Andreas fault. This report should stand as a rvhole and no part of the report should be excerpted or used to thc exclusion of any other part. This repoft complctes our scope of serviccs in accordanoe with our agreement, dated February 22,2006. Othcr serviccs that may be required, such as plan revicw and grading observation, arc additional scrvices and will be billed accotding to our Fcc Schcdulc in effect at thc timc scrvices are provided. Unless requested in writing, the client is responsible for distributing this report to the appropriate governing agency or other members of the design team. We appreciate the opportunity to providc our professional services. Please contact our office if there arc any questions or comments concerning this report or its rccommendations. Respectful Iy submitted, EARTH SYSTEMS SOUTHWEST Reviewed by, Hongbin IIuo, Ph.D. Project Enginecr SER/hh/csh/reh Distribution: Craig S. Ilill cE 3 8234 6/Coachella Valley Ilousing Coalition l/I(C Filc 2/BD Irile t I i TABLE OF CONTENTS Page EXECUTIVE SIJMMARY .,....ii Section I l.l 1.2 1.3 Scction 2 2.1 5.9 Section 6 6.1 I I I 2 3 3 3 4 4 4 4 5 5 6 7 2.2 Laboratory Testing..... Sgction 3 DISCUSSfON.............o.r.......r.................................,.................................D....... 3.1 Soil Conditions 3.2 Groundwater ...... 3.3 Geologic Setting 3.4 Geologic }Iazards. 3.4.1 Seismic Hazards 3.4.2 Secondary Hazards 3.4.3 Site Acceleration and Seismic Coefficients. Scction 4 CONCLIISIONS......................................................r.................r.......,..o..........9 Section 5 RBCOMMENDATIONS ............,.i....o...o,..........oo.....o..........o....r..........,........ I0 SITE DEVELOPMENT AND GRADING r05.1 Site Development - Grading l05.2 Excavations and tjtility Trenches .......,. I I5.3 Slope Stability of Graded Slopes ll STRT]CTI]RES....l2 ......... I 5 5.4 Foundations 5.5 Slabs-on-Grade 5.7 Mitigation of Soil Comosivity on Consrete5.8 Seismic Design Criteria 5.6 Retaining Walls ......... 14 Pavcmcnts...... ........... 16 LIMITATIONS AND ADDITIONAL SERVICES ............O"I""""""."""' I 8 Uniformity of Conditions and Limitations ... ......... l g 6.2 Additional Services...... l5 t9 REFERENCES.........o....o.t......o.o...or....................o...o.........r................r...r...r..r..r.........20 APPENDIX A Figure I - Site Location Map I?igure 2 - Boring Location Map Table I - Fault Parameters Tcrms and Symbols used on Boring Logs Soil Classification System Logs of Borings APPBNDIX B Laboratory Tcst Rcsults EAR'TFI SYSTEMS SOI]1'IIW[ST a ii EXECUTIVE SUMMARY Flarth Systerns Southwest has prepared this executive summary solely to provide a general overview of the report. T'he report itself should be relied upon for inforrnation about the findings, conclusions, recomrnendations, and other concerns. The site is located on the northwest corner of the intersection of Dure Palms Road ancl Avenue 48 in the City of La Quinta, California. The proposed development will consist of about 3l rnulti-unit buildings and a community center with pool and spa. We urderstand that the proposed structures will be of wood-frame and stucco construction supported with perimeter wall foundations and concrete slabs-on-grade. The proposed project may be constructed as planned, provided the recornmendations in this report are incorporated in the final design and construction. Site development will include clearing and grubbing of vegetation, site grading, building pad preparation, underground utilily installation, street and parking lot constnrction, and concrete driveway and sidewalks placement. Based on the non-uniform nature and hydrocollapse potential o1'the near surface soils, remedial site grading is recommended to provide unifclrm support for the founclations. We consider the most significant geologic hazard to the project to be the potential for moderate to severe seismic shaking that is likely to occur during the design life of the proposecl structures. The project site is located in the highly scismic Southern California region within the influence of several fault systems that are considered to be active or potentially active. The site is located in Seisnric Zone 4 of the 2001 California Building Code (CBC). Structures should bc designed in accordancc with the values and parameters given within the CBC. The seismic design parameters are presented in the fiollorving table and within the report. EAR'ITi SYS EMS SOUTI]WEST lll SUMMARY OF RECOMMENDATIONS The recommendations contained within this report are subject to the limitations presented in Section 6 of this report. We recommend that all individuals using this report read the limitations. Design Item Recommended Parameter Reference Section No. Foundations Allowable Bearing Pressure Continuous wall footings Pad =(Qolumn) footings 1,500 psf ,/ 2,000 psf /5.4 Foundation Spread Footing 5,4 Beari qg$aterials Elgineered fill Allowable Passive Pressure 250 pcf 5.4 Active Pressure 35 pcf 5.6 At-rest Pressure 55 pcf 5.6 Allowable Coefficient of Friction 0.35 5.4 Soi I Expansion Pqtentlal Very low (EI < 20)3.1 Geologic and Seismic Hazards Potential N.etiEiut..Z 3.4.2 Significant Fault and Magnitude San Andreas, ld7,7 3.4.3; 5.8 Irault 'l-ype A 3.4.3; 5.8 Seismic Zorrc 4 3.4.3; 5.8 Soil Profile Type S,,3.4.3; 5.8 Near-Source Distanie = 8.e ii,3.4.3; 5.8 Near Sonrce Factor ,No w 3.4.3; 5.8 Near Source Fac tor, N,t.Zg J 3.4.3 5.8 Pavemcnt TI equal to 4.5 3.O" AC I 4,0" AB 5.9 1'I equal to 5.0 3.0" AC 14.0" AB 5.9 Slabs Buil ding Floor Slabs On engineered fill 5,5 Modulus of Subgrade Rcaction 200 pci 5.5 Existing Site Conditions Existi !sFiu N/A Soil Corrosivity low sulfii es 7 . low chlo rides ,,/ severe resistivity (protcct buricd metal pjpes) 5,7 Groundwater Depth M 3.2 Estimated Fill and Cut 15 feet 1.1 EAR I I SYSTIMS SOTJTI IWDST a Type July I 3, 2A06 File No.: 09571-04 06-07 -734 GEOTECIINICAL ENGINEERING REPORT PROPOSED MIJLTI-FAMII,Y RESIDENTIAL DEVELOPMENT NORTHWEST CORNER OF DUNI] PALMS ROAD AND AVENUE 48 LA QUINTA, CALIITORNIA Scction I INTITODUCTION l.l Project Description This geotechnical engineering report has been prepared for the proposed multi-family residential development to be located on the northwest corner of the intersection of Dune Palms Road and Avenue 48 in the City of La Quinta, California. We understand that the proposed developrnent will include about 3 l multi-unit buildings and a community center with pool and spa. The proposed residential developntent will be single- or multi-story structures. We understand that the proposed structures will be of wood-frame and stucco construction and will be supported by conventional shallow continuous or pad footings. Site developntent will include clearing and grubbing of vegetation, site grading, building pad preparation, underground utility installation, street and parking lot construction, and concrete driveway and sidewalks placement. The development also consists of underground parking facilities. Based on existing site topography and ground conditions, site grading is expccted to consist of cuts and fills of about l5 feet. We used maximum column loads oL20 Lipr and a maximum wall loading ot.2 kigper linear foot as a basis for the foundation rdffifr?ndations. AII loading is assu-ed-i6-Sffead plus actual live load. I1 actual structural loading exceeds thesc assumed values, we would need to reevaluate the given recornmendations. 1,2 Site Dcscription The proposed rnulti-family residential development is to be constructed on the northwest corner of the intersection of Dune Palms Road and Ave nue 48 in the City of La Quinta, California. The sitc location is shown on Figure I in Appendix A, The site consists ol abandoned agricultural land described as a portion of the southeast quarter of the southwest quarter of Section2g, Township 5 South, Itange 7 East, San Bernardino baseline and meridian. The history of past use and developnrent of the property was not investigated as part of our scope of services. The northern portion of the site was previously occupied by structures assumed to be residential. Remnants of previous concrete foundations, wood, and other construction debris are present on the site. The southcast corner of the site appears to have been graded in the past, Grass clippings and clayey soils were obseryed in the southwest corner of the site and extend in a northwest direction off-site, There may be underground utilitics near and within the building area. These utility lines include, but are not limited to, domestic water, electric, sewer, telephonc, cable, and irrigation lines. F,AR'TI I SYS EMS SOUTHWIiSI' a July I 3, 2006 File No.: 09571-04 06-07 -7 34 1.3 Purpose and Scope of Work The purpose for our scrices was to evaluate the .site soil conditions and to provide professional opinions and recommcndations regarding the proposed development of the site. The scope of work included the following: from approximately l9 to 51,5 feet below cxisting grade. testing programs. This repofi contains the following: . Site developlnent and grading criteria. ' Excavation conditions and buried utility installations.. Structure foundation type and design. ' Allowable foundation bearing capacity and expected total and diffcrential settlements.. Concrete slabs-on-gradc.. Lateral earth pressures and coefficients. ' Mitigation of thc potcntial corrosivity of site soils to concrcte and stccl rcinforcement,. Seismic design paramcters.. Preliminary pavcmcnt stnrctural sections. Not Contained in This R.eport: Although available through Earth Systems Southwest, the current scope of our scrvices docs not includc: thc soil, surface water, groundwatcr, or air on, below, or adjacent to the subject property. The client did not direct ESSW to provide any service to invcstigate or detect the presence of moisture, mold, or other biological contaminates in or around any structtrre, or any service that was designed or intended to prevent or lower the risk or the occurrence of the amplification of the same. Client acknowledges that mold is ubiquitous to the environment, with mold amplification occurring when building materials are impacted by moisture. Clicnt furthcr acknowledgcs that site conditions are outside of ESSW's control and that mold amplification will likcly occtlr or continue to occur in the presence of moisture. As such, ESSW cannot and shall not be hcld responsiblc for thc occurrcnce or recurrencc of mold amplification. I]ARTI-I SYSTEMS SOUTI I WIJST 2 July 13,2006 File No. : 0957 l -04 06-07 -734 Section 2 METHODS OF INVESTIGATION 2.1 Field Exploration Eight exploratory borings were drilled to depths ranging fiom approximately I9 to 51.5 f'eet below the existing ground surface to observe the soil profile and to obtain samples for laboratory testing. The borings were drilled on May 12 and 16,2006 using 8-inch outside diameter hollow- stem augers, powered by a CME 55 truck-mounted drilling rig. The boring locations are shown on the boring location map, Irigure 2, in Appendix A. The locations shown are approximate, established by pacing and sighting from existing topographic featurcs. Samples were obtained within the tcst borings using a Standard Penetration (SPT) sampler (ASTM D 1586) and a Modified Califomia (MC) ring sampler (ASTM D 3550 with shoe similar to ASTM D I 586). Thc SPT sampler has a 2-inch outside diameter and a 1.38-inch inside diameter. The MC sampler has a 3-inch outside diameter and a 2.37-inch inside diarneter. The samples werc obtained by driving the sampler with a 140-pound automatic hammcr, dropping 30 inches in general accordance with ASTM D 1586. Recovered soil sarnples were seuled in containcrs and retumed to the laboratory. Bulk samples were also obtaincd from augcr cuttings, rcpresenting a mixture of soils encountered at thc depths noted. 'lhe final logs of the borings represent our interpretation of thc contents of the field logs and the results of laboratory testing performed on the samples obtained during the subsurface exploration. The final logs are included in Appendix A of this report. The stratification lincs represcnt the approximate boundaries between soil Upcs, although the transitions may be gradational. 2.2 Laboratory Testing Samples were reviewed along with field logs to selecl thosc that would be analyzed further,'Ihose selected for laboratory testing include soils that would bc exposed and used during grading and those deemed to be within thc influence of the proposed structure. Test results are presented in graphic and tabular form in Appendix B of this report. The tests were conductcd in general accordance with the procedures of the American Society for 'testing and Materials (ASTM) or othcr standardized methods as referenced below. Our testing program consisted of the following: cncountered. characteristics of selected samples were made by hydrometer and sieve analysis procedures. (collapse) potential of the soil. evaluate the potential adverse effects of the soil on concrctc and steel. [,AR'TI{ SYSTEMS SOUTHWEST 3 July I 3,2006 F'ile No. : 09571-04 06-07 -734 Section 3 DISCUSSION 3.1 Soil Conditions The field exploration indicates that site soils consist generally of silty sand, poorty graded sand with silt, and silt (Unified Soils Classification System symbols SM, SP-SM, and Uil. The boring logs provided in Appendix A include more detailecl dcscriptions o1' the soils encountered. The soils are visually classified to bc in the very low expansion (EI < 20) category in accordance with Tablc 18A-I-B of the California Building Code. In arid climatic regions, granular soils may havc a potential to collapse upon wetting. Collapse (hydroconsolidation) may occur when the solublc ccments (carbonates) in the soil matrix dissolve, causing the soil to dcnsifu from its loose configuration from dcposition. Consolidation testing indicates 2.2% collapse upon inundation and collapse is thereforc considercd a modcratc site risk. fhe hydroconsolidation potential is commonly mitigatcd by rccompaction of a zonc bcncath building pads. The sitc lies within a rccognized blow sand hazard arca. Finc particulatc mattcr (PMro) can create an air quality hazard if dust is blowing. Watering the surface, planting grass or Iandscaping, or placing hardscape normally mitigates this hazard. 3.2 Groundwater Free groundwatcr was not encountered in the borings during cxploration. The depth to groundwater at the site was cvaluated by contacting the Coachella Valley Water District [CVWD]. Mr. Brad Gummer of thc CVWD indicated the average depth to groundwater for Township 5 South, Range 7 East, Section 29,was 148.84 feet in 2004, The groundwater levels may fluctuatc with precipitation, inigation, drainagc, rcgional pumping from wclls. and sitc grading. Groundwater should not be a factor in design or construction at this site. 3.3 Geologic Setting Regional Geoloey: The site lies within the Coachella Valley, a part of the Colorado Desert geomorphic province. A significant feature within the Colorado Desert geomorphic province is the Salton Trough, The Salton Trough is a large northwest-trending structural depression that extcnds approximately I 80 nriles from the San Gorgonio Pass to the Gulf of California, Much of this dcpression in the area of the Salton Sea is below sea level. The Coachella Valley forms the northerly part of the Salton Trouglr. The Coachella Valley contains a thick sequence of Miocenc to Holocene sedimentary deposits. Mountains surrounding the Coachella Valley include the L.ittle San Bernardino Mountains on the northeast, foothills of the San Bernardino Moutrtains on the northwest, and the San Jacinto and Santa Rosa Mouptains on the southwest. These mountains expose prirrrarily Precambrian metamorphic and Mesozoic granitic rocks. The San Andreas fault zone within the Coachclla Valley consists of the Garnet EAR'I'H SYS'I'EMS SOUTI.IWES'I' 4 o July I 3, 2006 File No. : 09571-04 06-07-734 Hill fault, the Banning fault, and the Mission Creek fault that traverse along the northeast margin of the valley. Local Geolog.v: The project site is located approximately 60 fcct above mean sea level in the central part of the Coachclla Valley. The sediments within the valley consist of finc- to coarse-grained sands with interbedded clays, silts, gravcls, and cobblcs of aeolian (wind-blown), lacustrinc (lake-bcd), and alluvial (watcr-laid) origin. Dune sand is present on the property. The depth to crystalline bascment rock beneath thc site is estimatcd to be in excess of 2000 fect (Envicom, 1976). 3.4 Geologic lfazards Geologic hazards that may afflcct the region include scismi c hazards (ground shaking, surface fault rupturc, soil liquefaction, and other sccondary earthquakc-related hazards), slope instability, flooding, ground subsidcnce, and erosion, A discussion follows on the specifrc hazards to this site. 3.4.1 Seisrnic Hazards Seisrnic Sources: Several active faults or scismic zones lic within 62 miles (100 kilonreters) of the project site as shown on Table I in Appendix A. The primary seismic hazard to the site is strong ground shaking from earthquakes along the San Andreas and San Jacinto faults. The Maximum Magnitude Earthquake (Mrox) listed is from published geol<lgic information available for each lault (Cao et al., CGS, 2003). The Mrax corresponds to the maximum earthquake believed to be tectonically possible. Surfac.e Fault Ruptu.rg: The project site does not liq within a currently delineated State of California, Alquist-Priolo Earthquake Fault Zone (Hart, lggT). Well-delineated fault lines cross through this region as shorvn on California Geological Survey (CCS) maps (Jennings, I994); however, no active faults are mapped in the immediate vicinity of the site. Therefore, active fault rupture is unlikcly to occur at the projcct site. While fault rupture would most likcly occur along previously established fault traces, future fault rupture could occur at other locations. Historic Seismicity: Six his toric seismic events (5.9 M or greater) have significantly aflbcted the 100 years. They are as follows:Coachella Valley in the last Desert Hot Springs Earthquake - On December 4, 1948, a magnitude 6.5 Mr (6.0Mw) earthquake occurrcd east of Desert Hot Springs. This event was strongly felt in thc La Quinta area. Palm Springs Earthquake - A magnitude 5.9 Mr- (6.2Mw) earthquake occurrcd on July 8, I986 in the Painted Hills, causing minor surface creep of the Banning segment of the San Andreas fault. This event was strongly felt in the Coachella Valley area and caused structural damage, as well as injuries. Joshua Tree Earthquake - On April}2, 1992, a magnitude 6.1 ML (6.1Mw) earthquake occured in the mountains 9 miles east of Desert Hot Springs. Structural damage and minor injuries occurred in thc CoachcllaYalley area as a result of this earthquake. EARTH SYS'I]]MS SOT'THWI]ST 5 a a a t July I 3, 2006 File No.: A9571-04 06-07 -7 34 ' Landers und Big Bear Earlhquukes - Early on June 28, 1992, a magnitude 7.5 Ms (7.3Mw) earthquake occurred near Landers, the largest seismic event in Southern California {br 40 years. Surface rupture occumed just south of the town of Yucca Valley and extended some 43 miles toward Barstow. -About three hours later, a magnitude 6.6 Ms (6.4Mw) earthquake occurred near Big Bear Lake, No significant structural damage from these earthquakes was reported in the La Quinta area. ' Heclor ltline. Earthquake - On October 16, 1999, a magnitud e 7.lMw earthquake occurred on the Lavic Lake and Bullion Mountain faults north of Twentynine Palms. While this event was widely felt, no significant structural damage has becn reported in the Coachella Valley. Seismic Risk: While accurate earthquake predictions are not possible, various agencies have conducted statistical risk analyses. ln 2002, the California Geological Survey (CGS) and the United States Geological Survey (tjSGS) completed the latest generation of probabilistic seismic hazard maps. We have used these maps in our evaluation of the seismic risk at the site. The Working Group of Califomia Earthquake Probabilities (WGCEP, 1995) estimated a 22% conditional probability that a rnagnitudeT or greater earthquake may occur between 1994 and 2024 along the coachella segment of the San Andreas fault. Thc primary seismic risk at the site is a potential earthquake along the San Andreas fault. Geologists believe that the San Andreas fault has characteristic earthquakes that result from rupture of eac.h fault scgment. The estinrated characteristic earthquake is nragnitude 7 .7 for the Southern Segment of the fault (USGS, 2002). This segment has the longest elapsed time since rupture of any part of the San Andreas fault. The last rupture occumed about 1690 AD, based on dating by the USGS near Indio (WGCEP, 1995). This segment has also ruptured on about I 020, 1300, and 1450AD, with an avcrage recurrenoe interval of about 220years. The San Andreas fault may rupture in multiple segments, producing a higher magnitude earthquake. Recent paleoseismic studies suggest that the San Berrrardino Mountain Segment to thc north and the Coachella Segment mayhave ruptured together in 1450 and 1690 AD (WGCEP, 1995). 3.4.2 Secondary Hazards Secondary seismic hazards related to ground shaking include soil liquefaction, ground subsidence, tsunamis, and seiches. The site is far inland, so the hazard from tsunamis is non-existent. At the present time, no water storage reservoirs are located in the immediate vicinity of the site. Therefore, hazards from seichcs are considered negligible at this time. Soil Liquefactio!: Liquefaction is the loss of soil strength from sudden shock (usually earthquake shaking), causing the soil to become a fluid mass" ln general, for the eft'ects of Iiquefaction to be manifested at the surface, groundlvater levels must be within 50 feet of the ground surface and the soils u,ithin the saturated zone must also be susceptible to liquefaction. The site lies within a moderate liquefaction hazard area established by the 2002 Riverside County Gcneral PIan, based on historic high groundwater from 50 to I00 feet and very susceptible (Holocene) sedirnents. Quantitative liquefaction analyses are typically not required for general construction where groundwater depth exceeds 50 feet. The potential for liquefaction to occur at this site is negligible because the existing depth of groundwater beneath the site exceeds 50 feet and is not expected to return to levels above 50 feet. Therefore, no speciat mitigation for soil liquefoctiort is warranledfor this project, ENRTII SYSTEMS SOIJTI{WEST 6 .l I July 13,2006 File No. : 09571-04 06-07 -734 G*round Subsidence: The potential for seismically induced ground subsidence is considered to be low at the site. I)ry sands tend to settle and densify when subjected to strong earthquake shaking. The amount of subsidence is dependent on relative densiry of the soil, ground motion, and earlhquake duration. IJncompacted fill areas may be susceptible to seismically induced settlement. Slope Instability: The site is relatively flat. Therefore, potential hazards from slope instabilify, Iandslides, or debris florvs are considered negligible. Flooding: The project site does not lie within a designated FEMA 100-year flood plain. T'he project site is in an area where sheet flooding and erosion could occur. Appropriate project design, construction, and maintenance can minimize the site sheet flooding potential. 3.4.3 Site Acceleration and Seismic Coefficients Site Acceleration: The potcntial intensity of ground motion may be estimated by the horizontal peak ground acceleration (PGA), measured in "g" forces, Included in Table I are deterministic estimates of site acceleration from possible earthquakes at nearby faults. Ground motions are dependent primarily on the earlhquake magnitudc and distance to the seismogenic (rupture) zone. Accelerations are also dependent upon attenuation by rock and soil deposits, direction of rupture, and type of fault. For thesc reasons, ground motions may vary considerably in the same general area. This variability can be expressed statistically by a standard deviation about a mean relationship. The following table provides the probabilistic estimate of the PGA taken from the 2002 CGSruSGS seismic hazard maps. Estimate of PGA from 2002 CGS/USGS Probabilistic Seismic Hazard Ma Notes: L Based on a soft rock site, Ss7s, and soil amplification factor of 1.0 for Soil Profile Type Sp. 2001 CBC Seismic Coefficients: The California B uilding Code (CBC) seismic design criteria are bascd on a Design Basis Earthquake (DBE) that has an earthquake ground motion with a l0% probability of occurrence in 50 years. The I,GA estimate given above is provided for information on the seismic risk inherent in the CBC design. The seismic and site coefficients given in Chapter l6 of the 2001 California Building Code are provided in Section 5.8 of this report and belorv. EAR'I'H SYS'I'EMS SOU'I }IWESI 7 Risk Equivalent Return Period (years)PGA (e)t 10% exceedance in 50 years 475 0.s6 July I 3, 2006 I File No.: 09571-04 06-07 -7 34 2001 CBC Seismic Coefficicnts for Chapter 16 Seismic Provisions Seisrnic Zone: 4 Seismic ZoncFactor, Z: 0.4 Soil Profile Typc: Sp Seisrnic Sourcc Typc: A closest Distance to Known Seismic source: 8.9 km : 5.5 miles Ncar Sourcc Factor, Na: 1.05 Near Source Factor, Nv: l.Zg Seismic Coefficient, Ca: 0.46 : 0.44Na Seisrnic Cocfficient, Cv: 0.83 : 0,64Nv Rcfe[cncc Figurc l6-2 Table 16-l Tablc 16-J Table I6-U (San Andrcas fault) Tablc l6-5 Tablc 16-T Table 16-Q Table l6-R Seismic- I{azard Zones: The site lies within a moderate liquefaction hazard area established by the 2002 Rivcrside County General Plan, based on historic high groundwater from 50 to 100 feet and very susceptible (I{olocene) sediments. Quantitative liquefaction analyses are typically not required for general construction where groundwater depth exceeds 50 fcct. Thc potential fbr liquefaction to occur at this site is negligible because thc existing dcpth of groundwater bcncath the site cxceeds 50 teet and is not expectcd to return to levels abovc 50 fbct, EARI'H SYSTE:MS SOUI'FIWEST July I 3,2006 Irile No. : 0957 | -04 06-07 -734 Section 4 CONCLUSIONS The following is a sutnmary of our conclusiclns and professional opinions based on the data obtaincd from a rcview of selected technical litcrature and the site evaluation. General: provided the recommendations in this report are followed in the design and construction of this project. Geotechnical C on and Mitisa tion nearby faults, A major earthquake above magnitude 7 originating on the local segment of the San Andreas fault zone would be the critical seisrnic event that may affect the site within the design life of the proposed development. Engineered design and earthquake-resistant construction increase safety and allow development of seismic areas. a Type A seismic source as defined in the California Building Code. A qualified professional should design any permanent structure constructed on the site. Tbe minitnunl seismic design should comply with the 2001 edition of the California Building Code. the Coachella Valley area. Adherence to the grading and structural recommendations in this report should reduce potential settlement problerns from seismic forces, heavy raintall or irrigation, flooding, and the weight of the intended structures. seasonal flooding and erosion should be incorporated into site grading plans, Dust control should also be implemented during construction. Site grading should be in strict compliance with the requirements of the South Coast Air Quality Management District (sCAQMD). flooding, and landslides, are considered low or negligible on this site. their present condition to support structures, fill, and hardscape. The soils within the building and structuml areas will require moisture conditioning, over-excavation, and recompaction to improve bearing capacity and reduce the potential for differential settlement from static loading. Soils can be readily cut by normal grading equipment. Electrical resistivity testing of the soil suggests that site soils may present a "severe" potential for metal loss from electrochemical corrosion processes. EAIU'H SY STEMS SOTJTI-IWF:ST 9 July I 3, 2006 l0 File No. : 09571-04 06-07-734 Section 5 RECOMMENDATIONS SITE DEVELOPMIINT AND GRADING 5.1 Site Devclopment - Grading A representative of Earth Systems Southwest (ESSW) should observe site clearing, grading, and the bottoms of excavations before placing fill, Local variations in soil conditioni may wir.ant incrcasing the depth of recompaction and over-excavation. Cle-aring and Grubbing: At the start of sitc grading, existing vegctation, lrees, large roots, pavements, foundatiotts, non-cngineered fill, construction debris, trash, and abandoned underground utilities should be rernoved from the proposed building, stnrctural, and pavemenl areas. 'l'he surface shotrld be stripped of organic growth and removed frorl the construction area. Areas disturbed during clearing sltould be properly backfilled and compacted as described below. Dust control should also be implemented during construction. Site grading should be in strict compliance with the requirements of the South Coast Air Quality Managemelt District (sCAQMD). B-uilding Pad Preparation: Because of the relatively non-unifonn and under-compacted nature of the site soils, we recommend recompaction of soils in the building area. 'l'hc existing surf'ace soils within the building pad and foundation areas should be over-excavated to a minlmum of 4 feet below existing or finishcd grade or a minimum of 2 feet below the 1boting level (whichever is lower). For the underground parking lots. the over-excavation should d Z feet below the footing level, T'he over-excavation should extend for 5 feet beyond the outer edge of exterior footings. I'he bottom of the sub-excavation should be scarified, thoroughly moiiture conditioned, and recompacted to al least 90% relative compaction (ASTM O I SiZl for arl additional depth of I foot. Auxiliary Structures.subgrade Preparation: Auxiliary structures such as garden or retaining walls should have the foundation subgrade prepared similar to the building pud r..ommendations given above. The lateral extent of the over-excavation needs to extend onty 2 feet beyond the face of the footing. Subgrade Preparation: In areas to receive fill, pavements, or hardscape, the subgrade should be scarilicd, moisture conditioned, and compacted to al least g0% relative compactiop (ASTM D 1557) tbr a depth of I foot below finished subgrades. Compaction should be verified by testing. Engineered Fill Soils: -l'he native sandy soil is suitable lor use as engineered fill and utility trench backfill, provided it is free of significant organic or deleterious matter. T'he native soil should be placed in maximum 8-inch lifts (loose) and compacted to at least g1%relative compaction (ASTM D 1557) near its optimum moisture content, Compaction should be verified by testing. EAR'I]I SYSTEMS SOIJ'TI IWES'I' July I 3,2A06 il File No.: 09571 -04 06-07 -7 34 Imported lill soils (if needed) should be non-expansive, granular soils meeting the USCIS classifications of SM, SP-SM, or SW-SM with a maximum rock size of 3 inches and 5 to 35Yo passing the No. 200 sieve. The geotechnical engineer should evaluate the import fill soils before hatlling to the site. However, because ol'the potential variatigns within the borrow source, import soil will not be prequalified by ESSW. The imported fill shogld be placed in lifls no greater than 8 inches in loose thickness and compacted to at least 90% relative compaction (ASTM D 1557) near optimum moisture content. Slrinkage: The slrinkage factor for earlhu,ork is expected to mnge fi'onr 5 to 20 percent for the upper excavated or scarified sile soils. This estimate is based on compactive effort to acfiieve an average relative compaction of about 92% and may vary with contractor methods, Subsidence is estimated to range from 0.1 to 0.2 feet. Losses from site clearing and rernoval of existing site improvements may affect earthwork quantity calculations and should be considered. Site Drainage: Positive drainage should be maintained away from the structures (5% lbr 5 feet minimum) to prevent ponding and subsequent saturation of the tbundation soils. Gutters and downspottts should be considered as a means to convey water awrty from foundations if adequate drainage is not provided. Drainage should be maintained for paved areas. Water should not pond on or near paved al'eas. 5.2 Ilxcavations and Utility Trenches Excavations should be tnade in accordance with CaIOSHA requirements. Our site exploration and knowledge of the general area indicates there is a potential for caving of sitc excavations (trtilities, footings, etc.). Excavations within sandy soil should be kept moist, but not saturated, to reduce the potential of caving or sloughing. Where excavations over 4 l'eet deep are planned, lateral bracing or appropriate cut slopes of 1.5: I (horizontal:vertical) should be providerJ. No surcharge loads from stockpiled soils or construction materials should be allowed within a horizontal distance measured from the top of the excavation slope and equal to the depth of the excavation. Utiliqv-Irenches: Backfill of utilities within roads or public right-of-ways should be placed in conformance with the requirements of the governing agency (water district, public works department, etc.). Utility trench backfill within private properfy should be placed in conformance with tlte provisions of this reporl. In general, service lines extencling inside of properfy may be backfilled with native soils compacted to a minimum of 90% relative compaction, Backfill operations should be obsen ed and tested to monitor compliance with these recommepdations. 5.3 Slope Stability of Graded Slopes Unprotected, pennanent graded slopes should not be steeper than 3:l (horizontal:vertical) to reduce wind and rain erosion. Protected slopes with ground cover may be as steep as 2: l. However, maintenance with motorized equipm ent may not be possible at this inclination. Fill slopes should be overfilled and trimmed back to competent material. Slope stability calculations are not presented because of the expected minimal slope heights (less than 5 feet). EARTH SYSTEMS SOT]TI IWES'I- I July 1 3,2006 t2 File No.: 09571-04 06-07 -734 STRUCTURES In our profcssional opiniott, structure foundations can be supported on shallow foundations bearing on a zone of properly prepared ancl compacted soils placed as recommended in Scction 5.1. 'fhe recontmendations that follow are based on "very low" expansion categoty soils. 5.4 Foundations lrooting dcsign of widths, depths, and reinforcing are the responsibility of the Structural Engineer, considering the structural loading and the geotechnical parameters given in this report. A nrinimunl footing depth of 12 inches below lowest adjacent grade should be ntaintained for single-story structures and l8 inches below lowest adjacent grade for two-story structures. A representative of ESSW should observc foundation excavations beforc placement ol'reinforcing steel or concrete. L,oose soil or construction debris should be removed from footing excavations before placemcnt of concrete. Conv-entional Spread For.lndations: Allowable soil bearing pressures are given below for fottndations bearing on recompacted soils as described in Section 5.1. Allowable bearing pressures are net (wcight of footing and soil surcharge may be neglected). noted above: 1,500 psf for dead plus design live loads Allowable increases of 300 psf per each foot of additional footing width and 300 psf for each additional 0.5 foot of footing depth may bc used up to a maximum value of 3000 psf. 2,000 psf for dead plus design Iive loads Allowable increases of 200 psf per each foot of additional footing width and 400 psf for each additional 0.5 foot of footing depth may be used up to a maximum value of 3000 psf, A one-third (%) increase in the bearing pressure may be used when calculating resistalce to wind or seismic loads. The allowable bearing values indicated are based on the anticipated maximum loads stated in Section l.l of this report. If the anticipated loads exceed these values, the geotechnical engineer must reevaluate the allowable bearing values and the grading requirements. Minimum reinforcement for continuous wall footings (as spccified in the California Building Codc) should be two No. 4 steel reinforcing bars, one placed near the top and one placed near the bottom of the footing. This reinforcing is not intended to supersede any structural requirements provided by the structural cngineer. Expected Settlement: Estimated total static settlement should be less than I inch, based on footings founded on firm soils as recommended. Differential settlement between exterior and interior bearing membcrs should be less than Yz inch, expressed in a post-construction angular distortion ratio of 1:480 or less. EAR'N'I SYS'I-DMS SOU }IWEST July I 3,2006 File No.: 09571-04 06-07-734 Frictional And Lateral Coefficients: Lateral loads may be resisted by soil friction on the base of foundations and by passive resistance of the soils acting on foundation walls. An allowable coefficient of friction of 0.35 of dead load rnay be used. An allowable passive equivalent fluid prcssure of 250 pcf rnay also be used. These values include a factor of safety of I .5. Passive resistance and frictional resistance may be used in cornbination if the friction coefficient is reduced by onc-third. A one-third (%) increase in the passive pressure may be used when calculating resistance to wind or seismic loads. Lateral passive resistance is based on the assumption that backfill next to foundations is properly compacted. 5.5 Slabs-on-Grade Subgrade: Concrete slabs-on-grade and flatwork should be supported by compactsd soil placed in accordance with Section 5.1 of this report. Vapor Retarder: ln areas of moisture scnsitive floor coverings, an appropriate vapor retarder should be installed to reduce moisture transmission from the subgrade soil to the slab. For thesc areas, an impernteable membrane (IO-rnil thickness) should underlie the floor slabs. The tnembrane should be covered with 2 inches of sand to trelp protect it during construction and t<l aid in concrete curing. The sand should be lightly moistened just prior to placing the concrete. l,ow-slump concrete should be used to help reduce the potential for concrete shrinkage. The effectivcness of thc membrane is dependent upon its quality, the method of overlapping, its protection during construction, and the successful scaling of thc membrane around utility lines. Thefollowing minimum slab recornmendations are inlendetl to address geotechnical concerns sttclt os polential variotions of the subgrode and ore nol to be conslrued os supersetling ony slructurol desigtt. The design engineer ond/or project urchitect should ensure compliance witlt s8800 witlt regards to moisture and moisture vflpor. Slab Thickness and Reinfgrcemeru: Slab thickness and reinforccment of slabs-on-grade are contingent on thc recommendations of the structural engineer or architect and the expansion index of the supporting soil. Bascd upon our findings, a rnodulus of subgradc rcaction of approximatcly 200 pounds pcr cubic inch can bc uscd in concrctc slab dcsign for thc cxpectcd vcry low cxpansion subgrade. Concrete slabs and flatwork should be a minimum of 4 inches thick (actual, 4ot nominal). We suggest that the concrcte slabs bc reinforced with a minimum of No.3 rcbars at l8-inch centers, both horizontal directions, placed at slab mid-height to resist cracking, Concretc floor slabs may either be monolithically placed with the foundations or doweled after footing placement. Thc thickncss and reinforcing given are not intended to supersede any stnrctural requirements providcd by the structural engineer. The project architect or geotechnical engineer should continually observe all reinforcing steel in slabs during placement of concrcte to chcck for proper location within the slab. Control Joints: Control joints should bc provided in all concretc slabs-on-gradc at a maximurn spacing of 36 timcs thc slab thickness (12 feet maximum on-ccntcr, cach way) as rccommendcd by Amcrican Concretc Institutc (ACD guidclincs. All joints should form approxim atcly squarc patterns to rcducc the potential for randomly oricntcd contraction cracks. Contraction joints in EN RTH S Y STTiMS SOU'I'H W}.)S t3 t July 13,2006 t4 File No. : 09571_04 06-47 -734 the slabs should be tooled at the time of the pour or saw cut (% of slab clepth) within 8 hours of concrete placement. Construction (cold) joints should consist of thickened butt joipts with %-inch dowels at l8-inches on center or a thickened keyed-joint to resist vertical deflection at thejoint. All construction joints in exterior flatwork should be sealed to reduce the potential of moisture or foreign material intrusion. These procedures will reduce the potential for randomly oriented cracks, but rnay not prevent thcm from occurring. Quring and Ouality Control: T'he contrac.tor should take prccautions to reduce the potential of curling of slabs in this arid desert region using proper batching, placement, and curing methods. Curing is highly affected by temperature, wind, and humidity. Quality control proceclur.es may be used, including trial batch rnix designs, batch plant inspection, and on-site special inspection and testing. Typically, for this typc of construction and using 2500-psi concrete, rnany of thcse quality control procedures are not rcquired. 5.6 Retaining Walls Thc following table presents lateral earth pressures for use in retaining wall design. Thc values are given as equivalent fltrid pressures without surchargc loads or hydrostatic pressure. ILateral Pressures and Slidi ng Resistancc Granular Backfill Passive Pressure 375 pcf - level ground Active Prcssure (cantilever walls) Use when wall is itted to rotate 0.1% of wall he 35 pcf - level ground At-Rest Prcssurc restraincd walls Dynamic l,ateral Earth Pressure Acti at 0.61 where [l is of backfill in feet 55 level ground 50 pcf Base Lateral Sliding Resistance Dead load x Coefficient of Friction:0.s0 Notes: I . These values are ultimate values, A factor of safety of L5 should be used in stability analysis except for dynanric earth pressure rvhere a factor of safety of t.2 is acceptable. 2' Dynamic pressures are based on the Mononobe-Okabe I929 method, additive to active earth pressure' Walls retaining less than 6 feet of soil and not supporting inhabitable structures need not consider this increased pressure (reference: CBC Section 1630A. I . I ,5). Upward sloping backfill or surcharge loads from nearby footings can create larger lateral pressures. Should any walls be considered for retaining sloped backfill or placed next to foundations, otlr office should be contacted for recomrnencled design parameters. Surcharge loads should be considered if they cxist within a zone between the face of the wall and a plane projected 45 degrees upward from the base of the wall. The increasc in lateral earth prcssure should be taken as 35oh of the surcharge load within this zonc. Rctaining walls subjlctcd to traffic loads should include a uniform surcharge load equivalent to at least 2 feetof native soil. Drainage: A backdrain or an cquivalent system of backfill drainage should be incorporated into the retaining wall design. Our firm can provide construction details whcn the specific application is determined. Backfill immediately behind the rctaining structurc should be a frei-draining granular rnaterial. Watcrproofing should be according to the dcsigner's spccifications. Water I]ARTII SYSIEMS SOU'TIIWEST July I 3,2006 F'ile No.: 09571-04 06-07 -734 should not be allowed to pond near the top of thc wall. To accomplish this, the final backfill grade should be such that all water is diverted away lrom the retaining wall. Backfill ani Subgrade Compaction: Compaction on the retained side of the wall within a horizontal distance equal to one wall height should be performed by hand-operated or other lightweight compaction equipment, This is intended to reduce potential locked-in lateral pressures caused by compaction with heavy grading equipment. Foundation subgrade preparation should be as specificd in Section 5.1. 5.7 Mitigation of Soil Corrosivity on Concrete Selected chemical analyses fbr corrosivity were conducted on soil samples fiom the project site as shown in Appendix B. The native soils were found to have low sulfbte ion concentrations (22 to 45 ppm) and low chloride ion concentrations (127 to 144 ppm). Sulfate ions can attack the cementitious material in concrete, causing weakening of the cement matrix and eventual deterioration by raveling. Chloride ions can cause corrosion of reinforcing steel. The California Building (lode does not require any special provisions for concrete for these low concentrations as tested. Normal concrete mixes rnay be used. A minimttln concrete cover of three (3) inches should be provided around steel reinforcing or embedded components exposed to native soil or landscape water. Additionally, the concrete should be thoroughly vibrated during placement. Electrical resistivity testing of the soil suggests that the site soils may present a "severe" potential for metal loss from electrochemical corrosion processes. Corrosion protection of steel can be achieved by using epoxy corrosion inhibitors, asphalt coatings, cathodic protcction, or encapsulating with densely consolidated concrete. The information provided above should be considered prcliminary. These values can potentially change based on scveral factors, such as importing soil from another job site and the quality of construction water used during grading and subsequent landscape irigation. Earth Systents does not practice corrosion engineering. We recommend that a qualificd corrosion engineer evaluate the comosion potential on metal construction materials and concrete at the site to provide mitigation of corrosive cffects, if further guidance is desired. 5.8 Seismic Design Criteria This site is subject to strong ground shaking due to potcntial fault movemcnts along regional faults, including the San Andreas and San Jacinto faults. Engineered design and earthquake- resistant construction increase safety and allow development of seismic areas. The minimum seismic design should comply with the 2001 edition of the California Building Code using seisrnic coefficients given in the table below. EARI] I SYSTEMS SOUTHWT.]ST r5 July I 3, 2006 l6 File No.: 09571-04 06-07 -734 2001 CBC Seismic Coefficients for Chapter 16 Seismic Provisions Seismic Zone: 4 Seismic Zone Factor, Z: 0.4 Soil Profile Type : Su Seismic Source Type: A closest Distance to Known seismic source: 8.9 km:5.5 miles Near Source Factor, Na: 1.05 Near Source Factor, Nv: l.Zg Seismic Coefficient, Ca: A.46 : 0.44Na Seismic Coelfic.icnt, Cv: 0.83 :0.64Nv Referencg Figure l6-2 Table 16-l Table 16-J Table 16-U (San Andreas fault; Table 16-5 Table 16-T Table l6-Q Table l6-R The CBC seismic coefficients are based on scientific knowledge, engineering judgment, and compromise. If further information on seismic design is needed, a site-specific prclbabilistic seismic analysis should be conducted. The intent of the CRC lateral force requirements is to provide a structural design that will resist collapse to provide reasonable life safety from a major earthquake, but may experience some stt'uctuml and nonstructural damage. A fundamental tenet of seismic design is that inelastic yielding is allowed to adapt to the seisrnic demand on the structure. ln other words, tlamage i,s allowed. The CBC lateral force requirements should be considered a mininrunr design. The owner and the designer should evaluate the level of risk and pcrformance that is acceptable. Performance bascd criteria could be set in the design, The design engineer should exercise special care so that all components of the design are fully met with attention to providing a continuous load path. An adequate quality assurance and control program is urged during project construction to veriff that the design plans and good construction practices are fbllowed. This is especially important for sites lying close to the major seismic sources. Estimated peak (rnean plus one standard deviation) horizontal site accelerations based upon a probabilistic analysis (10% probability of occurrence in 50 years) is approximately 0.56g for a stiff soil site. Actual accelerations may be more or less than estimated. Vertical accelerations are typically % to % of the horizontal accelerations, but can equal or exceed the horizontal accelerations, depending upon the local site effects and amplification. 5.9 Pavenrents Since no traffic loading was provided by the design engineer or owner, lve have assumed traffic loading for comparative evaluation. The design engineer or owner should decide the appropriate traffic conditions for the pavements. Maintenance of proper drainage is advised to prolong the service lifc of the pavements. Water should not pond on or near paved areas. The following table provides our preliminary recommendations for pavement sections. Final pavement sections recommendations should be based ort design traffic indices and R-value tests conclucted cluring grading after actual subgrade soils are exposed. EARTH SYS'|EMS SOUTI] WES]' July I 3, 2006 t7 Filc No. : 09571-04 06-07-734 PRELIMINARY RECOMMENDED PAVEMENTS SECTIONS R-Value Sub Soils - 50 assumed Des Method - CALTRANS 1995 Notes: I'Asphaltic concrctc should be Caltrans, Typc B, t/z-in. or t/,t-in, nraximum-medium grading and compactccl to a minimum of 95% of the 75-blow Marshall clensity (ASTM D 1559) or equivatenr. 2.Aggtcgate base should be Caltrans Class 2 (%in. maximum) and compacted to a minimum of 9So/o of ASTM D1557 maximum dry densiry near its optimurn moisture. 3, All pavements should bc placed on l2 inches of moisture-conditioned subgradc, compacted to a nrininrun.t of 90yo of ASTM D 1557 maximum dry densiry near its optimum moisture. 4' Portland cement concrete should have a minimum of 3250 psi compressive strength at 28 days. 5' Eqtrivalent Standard Specifications for Public Works Construction (Greenbook) may be used instcad of Caltrans spccifications for asphaltic concretc and aggregatc base. Flexible Pavements Rigid Pavements Traffic Index (Assumed) Pavement Use 'Asphaltic Concrete Thickness (lnches) Aggregate Base Thickness (lnches) Portland Cement Concrete (Inches) Aggregate Base Thickness (lnches) 4.5 Auto Parking Areas 3.0 4.0 4.0 4.0 5.0 Residential Streets 3.0 4.0 5.0 4.0 EA II'I'H SY S'I'EM S SOU'IH W I.]S'T C July I 3, 2006 t8 File No.: 09571-04 06-07 -734 Section 6 LIMITATIONS AND ADDITIONAL SERVICES 6.1 Uniformity of Conditions and Limitations Our findings and recommendations in this report are based on selected points of field exploration, laboratory testing, and our understanding of the proposed project. Furtherrnore, our findings and recommendations are based on the assumption that soil conditions do not vary significantly from those found at specific exploratory locations. Variatiols in soil or groundwater conditions could exist between and beyond the exploration points. l'he naturc and extcnt of these variations may not become evident until construction. Variations in soil or groundwater may require additional studies, consultation, and possiblc revisions 1o our recommendations. Findings of this report are valid as of the issued date of the report. I{owever, changes in conditions of a property can occur with passage of time, whether they are from natural processes or works of man, on this or adjoining properties. In addition, changes in applicable standards occur, whether they result from legislation or broadening of knowledge. Accordingly, findings of this rrport may be invalidated wholly or partially by changes outside our control. T'herefore, this report is subject to review and should not be relied upon afler a period of one year. In the event that any changes in the nature, design, or location of structures are planned, the conclusions and recolnmendations contained in this report shall not be considered valid unless the changes are rcviewed and the conclusions of this report arc modified or verified in writing. This report is issued with the understanding that the owner or the owner's representative has the responsibility to bring the information and recommendations contained hercin to the attention of the architect and engineers for the project so that they are incorporated into the plans and specifications for the project. The owner or the owner's representative also has the responsibility to veriff that the general contractor and all subcontractors follow such recommendations. It is further understood that the owner or the owner's rcpresentative is responsible for subrnittal of this repofl to the appropriate governing agencies. As the Geotechnical Engineer of Record for this project, Earth Systems Southwest (ESSW) has striven to provide our services in accordance with gencrally accepted geotechnical engineering practices in this locality at this time. No warranty or guarantee is express ol'implied. This report was prepared br the exclusive use of the Client and the Client's authorized agents. ESSW should be provided the opportunity for a general review of finat design and specifications in order that earthwork and foundation recommendations may be properly interpreted and implemented in the design and specifications. If ESSW is not accordcd the privilege of making this recornmendcd review, we can assume no responsibility for misinterpretation of our recommendations. Although available through HSSW, the current scope of our services does not include an environmental asscssment or an investigation for the presence or absence of wetlands, hazardous EAR'TH SYSTEMS SOtJl'IIWEST a July I 3,2006 19 Irile No. : 0957 I -04 06-07 -7 34 or toxic materials in the soil, surface water, groundwater, or air on, below, or acljacent to the subject property. 6.2 Additional Services 'fhis report is based on the assumption that an adequate program of client consultation, construction monitoring, and testing will be performed during the final design and construction phases to check compliance with these recommendations. Maintaining ESSW as the geotechnical consultant from beginning to end of the project will provide continuity of services. The geotechnical engineering firm providing tests and obserttations shalt assume the re sportsibility o.[ Gecttechnical Engi neer o/' Record, Construction monitoring and testing would be additional services provided by our firm. T'he costs of these services are not included in our present fee arrangements, but can be obtainecl fiom our offioe. l'he reoommended review, tests, and observations includc, but are not necessarily limited to, the following: Consultation during the final design stages of the project. A review of the building and grading plans to observe that recommendations of our report have been properly implemented into the design. Observation and testing during site preparation, grading, and placement of engineered fill as required by CBC Sections 1701 and 3317 or local grading ordinances. Consultation as needed during construction. O a a a -o0o- Appendices as cited are attached and complete this report, EAR]'II SYSI'EMS SOUI]J WES'T July I 3,2006 Irile No. : 09571 -04 06-07-734 REFERENCES Abrahamson, N., and Shedlock, K., edilors, 1997, Ground motion attenuation rclationships: Seismological Rcsearch Letters, J. 68, no. l, January 1997 special issue, 256 p. Americatr Concrcte Institute (ACI), 2004, ACI Manual of Concrete Practice, Parts I through 5. American Society of Civil Engineers (ASCE), 2003, Minimum Design Loads for Buildilgs and Other Structures, ASCE 7-02 California Department of Water Resourccs, 1964, Coachella Vallcy Invcstigation, Bullctin No. I 08, 146 pp. California Geologic Survey (CGS), 1997, Guidelines for Evaluating and Mitigating Seismic Hazards in Califbrnia, Special Publicati on I17. Cao, T, Bryant, w.A., Rowhandel, 8., Branum, D., and Wills, C,, 2003, The Revised 2002 California Probabilistic Seismic Hazard Maps, Califomia Ceologic Survey (CGS), June 2003. Envicom Corporation and the County of Riverside Planning Department, 1976, Seismic Safety and Safety General PIan Elemerrts Technical Report, County of Riverside. Frankel, A.D., et al., 2002, Documentation lbr the 2002 Update of the National Seismic qlazard Maps, USGS Open-File Report 02-420. Hart, 8.W., 1997, Fault-Rupture Hazard Zones in Califomia: California Division of Mines and Geology Special Publicati on 42. International Code Courcil (ICC), 2002, California Building Code, 2001Edition. Jennings, C.W, 1994, Fault Activity Mup of Califomia and Adjacent Arcas: California Division of Mines and Geology, Gcological Data Map No. 6, scale l:750,000. Petersen, M.D., Bryant, W.A., Cramer, C.H., Cao, T., Reiclrle, M.S., I?rankel, A.D., Leinkaemper, J.J., McCrory, P.A., and Schwarz,D.P., 1996, Probabilistic SeismicHazard Assessment for the State of California: California Division of Mines and Geology Open-File Report 96-08. Riverside County Planning Department, 2002, Geotechnical Element of the fuverside Counfy General PIan - Hearing Drafl. Rogers, T.H., 1966, Geologic Map of California - Santa Ana Shcet, California Division of Mines and Gcology Regional Map Suies, scalc l:250,000. Tokimatsu, K, and Seed, H.B., 1987, Evaluation of Setllenrents in Sands Due 'Io Earthquake Shaking, ASCE, Journal of Geotechnical Engineering, Vol. I13, No. B, August 1987. Wallace, R. E., 1990, The San Andreas Fault System, Califomia: U.S. Ceological Survcy Professional Paper I515, 283 p. Working Group on California Earthquake Probabilities, 1995, Seismic Hazards in Southern California: Probable Earthquakes, 1994-2A24: Bulletin of the Seismological Society of America, Vol. 85, No. 2, pp.379-439. ENRTII SYSTEMS SOUTHW}.,ST 20 D APPENDIX A Figure I - Site Location Map Figure 2 - Boring Location Map Table I - Fault Parameters 'l'erms and Symbols used on Boring Logs Soil Classification System Logs of Borings ' EARTTI SYS'I'EMS SOUTI{WEST ,t $ t,' , )"1 F $!tL Iq *-41h\ H[i s,*t"P#tr,.\ E* i, Fhr rrifF* \ft-n? ++ t, L} Hl'I ;h \ ilA'- : "'. H4 if ti:,,u3: '*,, , '!.h,.'t;-",, \ , 'T ._, , !1*-J*. 5: Y.._'i -o.A*,ht= ti_+ !. 6.1\+ o if a.l;r :- i.r o--+ c, =H.N FItt 3 (3qcrq BIANF(v, oooCI(\a h.:, 0a h:. \+ o ct(,t,6nl,\ --ao ir. =\+o (,oo ro Its-rr} o(,o foF ff, g,o(f(D qr> rrrrl oo C}o a'-)F. tYt I 160lg,o,w 565000 I 16" I 7'l 5"W 566000 I 16" I 6'30'ly 561000 56E000 560000 505000 I16"18',00w 566000 I 16" l7t I s"tt, 561000 I16"16'J0'ty 568000 569000 I 160 I 5'4 5'ty ll6"l5'45',W Feet 0 500 1,000 2,000 3,000 4,000 5,000 I ; rl.F Pat t ./lI i /lrr : 14rtrl,(;rt .! lr t. ll ilII I+o .aJ_'"lr 2 I ac :*t-+ , ' /:,/++ J Trr (' ) t.+ li I ri, \?tt Ii: .-.irr( r L fi IL r._ t L., lt .J i) -(.1 '1. ve'r!!4 .:.!' ''1.!, .': -l ": \.,:- . ..1 Ii Irl.- .t, '.i7 tr"' .\i......, '':'l '-' j'', ''' l. 'r i''' - i,r'' !-?. ' ''' ilr.'.,.*' i.f\,..:"vtLtErr- - i.''.'::E+4'?f i .', I l.'lrr' ' ,E' i-' AVENUE rl. II l .:; :' + tj: lI t' '-ll .l . i,?t. 3s;i w.rr I I ! .il '.r.t.4 l.r , '-n iak IT h tI -l I't.li I ,il It !, t .aveNuri *-j'- - tr' IuE- tf ll .ti. ' [r ,;;, l*-':1 -. l( [Trerlcr Pei ' \ I rruhit 1 ' 'L: ,L .riiLJ"l,,,' :. { a+-1.-- We,l'fil -l- r:sal,[: .u_E_N '". J 7'ni,!,, ti\t a tr t l,:j''{'T i I ..r I tl z 1:4t' '!t'/ l 1 \; I i 3 [ -'r - " t"-'.. r'i '!,o ii I 4- ;2 -J; VJell l I I I It. Avenue 48 TEs -'.,1 It i '^-'. +. + eil.l /i bo I {: I It 30 WcJl t ii.tii I t ',1 il 'il'i l,i ni f *, ir..'.,t\ ./, i 1- - - E Figure 1 Site Location Map Multi-Family Residential Development NWC Dune Palms Road & Avenue 48 La Quinta Riverside Count California Earth Systems $outhwrst Reference: www. terraserverusa. com r NLEGEND Site Boundary I F .i,'i',,,., I I ) ,l ' 'l IrI tliqIL f0. ! ) t. '| | l. I .. .t.: '.- .l:: ) a i I l I I ! f-f -l o B4 I I ,tI I \ H 1r L- - rt: o @s E{Etl H* t E oo|oaN f.l - a- Al\to <)olnoc{ ra ^l\to s66700 566700 566E00 566800 ll6"l6'42"W 5669ffi 567000 s67000 567I00 5S7 r 00 ao( or t\aFt, orJvg) o.a?-!/) t,o (J'(rt(\I Ffi oo{?o)(\. I\ta c,otrlotf{F{r) oot\l o)rI 4' 566000 116016,42,w 0 50 100 200 300 400 500 Feel - Figure 2 Boring Location Map Multi-Family Residential Development NWC Dune Palms Road & Avenue 48 Southwcrt La Quinta, Riverside Cou , California Earth Systems LEGEND O Approximate Boring Location l,a.rrrrta i t Site Boundary tarrarr. Reference : www. globexplorer.com It N > 07 t13t06 File No.: 09571-04 , r-# t: lrr r n Lt+ ll ,). I| {r' ll 1t' Tfl r .i' + a I I l. a aU u -l D 1- ,f 'Wf,) ? f ' I I e @fl I.,o d n:€It e eo' 'l a I I , t. a t I,t-? Ft'=[-: .FHI;F t't+-:alr!f F '*f*- r: Fr:, 't[til I I -b.i I a I .{ '.iJ,' ll .4 iJ) j f.:, , tt-I .'ry I a E 7 I It /I)no fi).8 Ittt I + JI a- t u n JI I II*t r t NWC Dune Palms and Avenue 48 , La Quinta. CA 09s7 I -04 Table I Fault Parameters & Deterministic Estimates of ilIean Peak Ground Acceleration I Notcs: l. Jennings ( I994) and California Gcologic Survcy (CGS) (2003) 2. CGS (2003), SS :.Strike-Slip, ItV ='Revcrsc, DS.= Dip Slip (normal), B'f - Blind'l'hrust 3. 2001 CBC, rvhcre'l'ypeA faults: Mmax>7&sliprate>5 mm/yr&'IypeC fautts: Mmax<6.5 &sliprate<2 mnr/yr 4, CCS (2003) 5. 'Ihe cstimates of the mean Site PGA are based on the following anenuation relationships: Averagc ofl (l) 1997 Boore, Joyner & Fumal; (2) 1997 Sadigh et al; (3) 1997 Campbell, (4) 1997 Abrahanson & Silva (mean plus signra values are about 1.5 to 1.6 times higher) Based on Sitc Coordinates: 33,704 N l.atirude, 116.277 W Longtudc and Site Soil 'l'ypc D Fault Name or Seismic Zone m knr Dislnnce from Site l aull 1'ype Mw Maxinunr Magnitude lllma.r Avg Slip Rrtle Avg Rclurn l'criod F'nutt Le ngth illcrn Silr PGA Reference Notes:I J ) San Andreas - Southern San Andreas - Banning Branch San Andreas - Mission Crk, Branch Blue Cut San Jacinto (Hot Spgs - Buck Ridge) Burnt Mtn. Eurcka Peak San Jacinto-Anza San Jacinto-Coyote Creek Morongo Pinto Mountain Ilmerson So. - Copper Mtn. Landers Pisgah-Bullion Mtn.-Mesquite Lk San Jacinto - Borrego San Jacinto-San Jacinto Valley North Frontal l.'ault Zone (East) Earthquake Valley Brawley Seismic Zone Johnson Valley (Northern) F)lsinore-Ju lian Calico - I{idalgo Els inore-Temecula Elmore Ranch Lenwood-Lockhart-Old Woman Sprgs North Frontal Irault Zone (West) Els inore-Coyote Mou ntain Superstition Mtn. (San Jacinto) Superstition Hills (San Jacinto) I{elendale - S. Lockhardt San Jacinto-San Bernardino Elsinore-Glen Ivy 5.5 s.9 s.9 14.3 l7,l 17.6 18.5 21.4 21.8 29.0 30.s 31.8 32.7 33.8 35.I 36.9 38.9 40.1 41,0 43.s 44.2 45.2 48.0 49.2 49.3 s0.0 sl.2 53.2 54.0 57.2 59.1 61.7 8.9 9.5 9.5 22.9 27.4 28.4 29.8 34.4 3s. I 46.7 49.t 51,2 52,7 54.4 56.5 s9.3 6?.6 64.5 66.1 70.0 71.1 72.7 77.2 79.2 79.4 80.s 82,4 85,6 86.9 92.t 95.2 99.3 A A A C C B B A B C B B B B B B B B B B A B B B B B B B B B B B SS SS SS SS SS SS SS SS SS SS SS SS SS SS SS SS RV SS SS SS SS SS SS SS SS RV SS SS SS SS SS SS 7.? 7.2 7.2 6.8 6.5 6.5 6.4 7.2 6.8 6.5 7.2 7.0 7,3 7.3 6,6 6.9 6.7 6.5 6,4 6,7 7.1 7.3 6.8 6.6 7.5 7,2 6.8 6,6 6.6 7.3 6.7 6.8 24 l0 25 I 2 0.6 0.6 t2 4 0.6 2.5 0.6 0.6 0.6 4 l2 0.5 2 25 0.6 5 0.6 5 I 0.6 I 4 5 4 0.6 t2 5 220 220 220 760 354 5000 5000 250 175 r 170 499 5000 5000 s000 17s 83 t727 3sl 24 5000 340 5000 240 225 5000 r3l4 62s s00 2s0 5000 r00 340 t99 98 95 30 70 2l t9 9t 4t 23 74 54 83 89 29 43 27 20 42 35 76 9s 43 29 145 50 39 24 23 97 36 36 0.44 0.37 0.37 0.17 0.12 0.t2 0.1t 0.14 0.1I 0.01 0.10 0.09 0.10 0.10 0.06 0.07 0.08 0.0s 0.05 0.06 0.07 0.06 0.05 0.0s 0.08 0.08 0.0s 0.04 0.04 0.06 0.04 0.04 EAR'I'I.I SYSTEMS SOUTI.IWESI' Terms and Symbols used on Boring Logs e Earth Systems Southwest DESCRIPTIVE SOIL CLASSIFICATION soil classification is basod on ASTM Designations D 2487 and D 2488 (Unitied Soil Classllication System). tnformaflon on each borlnglog is a compilation of subsurface conditions obtainsd from the field as vr€ll as ftom laboratory'tostinb of selected samples. Ttriindicated boundaries belween strata on the boring logs are approximate oirty an-O may be tra;sltional. SOIL GRAIN SIZE U.S. STANDARD SIEVE 12"40 00 305 76.2 '1 9, 1 4,76 2.00 0.42 SOIL GRAIN SIZE IN MILLIMETERS 0.074 0.002 RELATIVE DENSIW OF GRANULAR SOTLS (GRAVELS, SANDS, AND NON-PLAST|C STLTS) Very Loose Loose Medium Dense Dense Very Dense Very Soft Soft Medium Stiff stiff Very Stiff Hard Molsture Conditlon: Molsture Content: Dry Density: Dry....,,.. RD=0-30 RD=30-50 RD=50-70 RD=70-90 RD=90-100 'C=0-250 psf C=250-500 psf C=500-1000 psf C=1000-2000 psf C=2000-4000 psf c>4000 MOISTURE CONDITION .......Absence of moisture, dusty, dry to the touch ..............Slight indication of moisture ..............Co|or change with short period of air exposure (granular soil) Below optimum moisture content (cohesive soil) .High degree of saturation by visual and touch (granular soil) Above optimum moisture content (cohesive soil) Free surface water Easity push a 112-inch reinforcing rod by hand Push a 'll?-inch reinforcing rod by hand Easily drive a 112-inch reinforcing rod with hammer Drive a 112-inch reinforcing rod 1 foot with difficulty by a hammer Drive a 1|Z-inch reinforcing rod a few inches with hammer Squeezes between fingers Easily molded by finger pressure Molded by strong finger pressure Dented by strong finger pressure Dented slightly by finger pressure Dented slightly by a pencil point or thumbnail RELATIVE PROPORTIONS Trace.......,.....minor amount (.5%) with/some......significant amount modifier/and...sufficlent amount to infl uence material behavior (Typically >30%) LOG KEY SYMBOLS Bulk, Bag or Grab Sample Standard Penetration Split Spoon Sampler (2" outside diameter) Modified Califomia Sampler (3" outside diameter) No Recovery nN=0-4 N=5-10 N=11-30 N=31-50 N>50 'N=Blows per foot in the Standard Penotration Test at 60% thaor€tical energy. For the 3-inch diam€tBr Modifi€d California sampler,14lPound weight, multiply the blow count by 0.63 (about 2/3) to sstimats N. lf automatic hammer is used, multiply a factor of ' 1.3 to 1.5 to Bslimate N. RDERelativB Density (%). C=Undrained shear strength (cohssion). coNstsTENcy oF coHEstvE sotLs (cLAy oR cLAyEy sotls) "N=0-1 N=2-4 N=5-8 N=9-15 N=1&30 N>30 II,IOISTURE DENSITY An observational term; dry, damp, moist, wet, saturated. The weight of water in a sample divided by the weight of dry soil in the soil sample expressed as a percentage. The pounds of dry soil in a cubic foot. Damp Moist. Wet. Saturated. DESCRIPTION Nonplastic Low Medium High PLASTICITY FIELD TEST A 1/8 in. (3-mm) thread cannot be rolled at any moisture content. The thread can barely be rolled. The thread is easy to roll and not much time is required to reach the plastic limit. The thread can be rerolled severaltimes after reaching the plastie limit. t I t NGROUNDWATER LEVEL V Water Level (measured or after drilting) V Water Level (during drilling) GRAVEL SANDBOULDERSCOBBLESCOARSEFINECOARSEMEDIUM FINE SILT CLAY a I MAJOR DIVISIONS GRAPHIC SYMBOL LETTER SYMBOL TYPICAL DESCRIPTIONS a a a a t GW Well-graded gravels, gravel-sand mixtures, little or no fines ii.ti'rli:it:iJ.'r'.'i-l'.1'.rJ;J;l CLEAN GRAVELS < sVo FINES GP Poorly-graded gravels, gravel-sand mixtures. Little or no fines GM Silty gravels, gravel-sand-silt mixtures GRAVEL AND GRAVELLY SOILS More than 50% of coarse fraction rglalocd on No. 4 sieve GRAVELS WITH FINES > 12yo FINES GC Clayey gravels, gra vel-sa n d- cl ay mixtures SW Well-graded sands, gravelly sands, little or no finesCLEAN SAND (Little or no fines) I 5o/o SP Poorly-graded sands, gravelly sands, little or no fines ililiilililiilii iliil SM Silty sands, sand-silt mixtures COARSE GRAINED SOILS More than 50% of material is larger than No.200 sieve size SAND AND SANDY SOILS More than 5oo/o ot coarse fraction passing No. 4 sieve SAND WITH FINES (appreciable amount of fines) > 12o/o SC Clayey sands, sand-clay mixtures 1ililil tilil ML lnorganic silts and very flne sands, rock flour, silty low clayey fine sands or clayey silts with slight ptasticity CL lnorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays LIQUID LIMIT LESS THAN 50 OL Organic silts and organic silty clays of low plasticity MH lnorganic silty, micaceous, or diatomaceous flne sand or silty soils .r't,/.,,/ ,/i ,t/ lnorganic clays of high plasticity, fat clays FINE.GRAINED SOILS 50% or more of material is smaller than No.200 sieve size SILTS AND CLAYS LIQUID LIMIT GREATER THAN 50 OH Organic clays of medium to high plastlcity, organic silts HIGHLY ORGANIC SOILS PT Peat, humus, swamp soils with high organic contents VARIOUS SOILS AND MAN MADE MATERIALS Fill Materials MAN MADE MATERIALS Asphalt and concrete Soil Classification System Earth Systems Southwest IHHHHHHHHHHHHI ililililililililililililil i---------IIIIIIIIIIITTIIIITIIIIIIIIIIIIIITI rIII'I-IIIIII Itt a ar a. a.li ar t. a t. ar ar a. t.ar a. a. a CH Boring No: B-I Project Name: NWC Dune Palms Rd. & Ave, 48, La Quinla, CA F'ile Number: 09571-04 Boring I,ocation: See Figurc 2 Drilling Date: May 12,2006 Drilling lvlethod; 8" [Iollorv Stem Auger DrillType: Williams CME 55 w/Auto Hamnrer l,ogged By: Dirk Wiggins tt- o.q) Sanrpl Typc *r-Jo-frv) e l:- EU Ao a- Penetration Resistance (BlowV6") u.o Eha aOa )r,a 0) qi' |.vo \o9o\E:6L'59 <rEzoU Graphic'l'rend lJlow Counl Dry Density Dcscription of Units Notc: The stralification lines shown represent thc approximate boundary bclrvcen soil and/or rock typcs and the transition nray be gradational. Page I of I @ Southwest 79-E I I B Cormtry Club Drivc, llcnnuda Duncs, CA 92203 Phonc 345-l Fax 345-71t5 Earth Systems l0 l5 20 z5 30 35 40 50 45 55 5 t SM SM SILTY SAND: pale yellowish brown, medium dense, dry, fine to nredium grained pale to modcratc yellowish brorvn, damp .SM SILTY SAND: pale yellowish brown, medium dense, damp, fine to medium grained 4,6,e 4,6, 1 0 5,9,14 J,5,8 88 92 92 89 t0 4 l T'otal Depth 21.5 fbet No Groundrvater Encountcred 60 SILTY SAND: pale yellowish brown, very loose, dry, fine to medium grained I a e Earth Systems 79.81I B Country Club Drive, Bcnrruda Duncs, CA 92203 Phonc 345- |I;ax 345-73 I 5 Southwest 5 25 30 r0 t5 20 35 40 45 50 55 Boring No: B-2 ProjectNamc: NWC Dune Palms ltd. & Avc. 48, La euintn, CA Filc Nrrmber: 09571-A4 Boring Location: Scc Figurc 2 Drilling Datc: May 12,2006 Drilling Method: S" Hollow Stem Augcr Drill'lype: Williarns CM[,: 55 w/Auto Hammer Loggcd By: Dirk Wiggins lr- o-(.)o Sample Type *r- =a-ca(/l =-rdo oo Penctration Resistance (Illorvs/6") o.o ts U) (n O(n) a lD q:!a& f'v \o0) o\ a,'= (U€E20O Description of Units Note: 'l'he stratilication lines shorvn reprcsent the approximate boundary belween soil and/or rock typcs and the transition may bc gradational. Graphic'l'rend Blorv Count Dry Density Page I ol'l 2.4,4 2,3,.5 4,6,9 6,t2,20 SP-SM 85 88 86 2 () 2 SAND WITH SILT: pale yellowish brorvn, loose, dry, fine to nrediurn grained, rvith mica damp, silty sand lcnscs mcclium densc, dry densc 'l'otal Depth l9 feet No Groundwatcr Encountered 6oL a @ Earth tems Southwest 79-81 I B Country Club Drivc, Bcnnuda Dunes, CA 92203 Phonc 345- I 588, Fax 145-7 3 I 5 Ifl. t o. C)o \oQ) o\ .j=U' L4.r 0-,€Eao() Boring No: B-3 Projcct Name: NWC Dunc Palms Rd. & Ave, 48, La euinta, CA Filc Number; 09571-04 Boring l,ocation: See F'igurc 2 Drilling Datc: May 16, 2006 Drilling iVlcthod: 8" Ilollow Stem Augcr Drill'lype: Williams CME 55 rry'Auro l{ammer t.ogged By: Dirk Wiggins Description of Units Note: Thc stralification lines shorvrr represcnl llrc approximale boultdary bctwccn stril and/or rock lypcs and thc transition may be gradational, Page I of I U)U(n) o.o E)rv) q-.: (t U Sanrplc '11'pe >..=t, c) *. b-o Graphic Trend Illorv Counl Dry Density .vtO 6(,,Z Penelration Resistance (BlowV6") 5 20 t0 l5 25 30 35 45 50 55 40 .SP.SM SM SP.SM SAND WITII SIL'I-: pale yellowish brorvn, loosc, dry, finc to ntediunr grained dry to damp, lenses ol'silty sand SILTY SAND: pale yellowish brorvn, medium dense, damp, fine to mediunt grained SAND WI'I'H SILT: pale yellorvish brorvn, dense, damp, fine to mediurn grained mediurn dense, damp dty, tracc coarsc graincd sand 2,3,5 3,4,7 4,9,10 6,12,15 7,t2,t0 7,14,22 100 92 97 92 90 92 3 4 l 4 6 2 'l'otal Depth 31.5 I'eet No Gro undwater l"lncountered 60 ,ll,l..J a Earth Drilling f)ate: May 16,2006 Drilling Method: S" Hollorv Stem Auger Drill'l'ype: Williams CME 55 rv/Auto Ilammcr Logtrged By: Dirk Wiggins lr- Er 0)o Sa mpl Typo e H?(.) Ao't p- =,L6v) E.o E>.cn a(-)v) )r U, 0)q. |'vo \o9o\ E,A'5E l<.E20O Boring No: B-4 Projcct Nalne: NWC Dune Palms Rd, & Ave. 48, La Quinta, CA File Nrrmber: 09571-04 Boring Location: See Figure 2 Description of Units Note: Thc stralificalion lines shown represenl the approxintate boundary belwcen soil and/or rock types and the transition may bc gradational Pagc I ol'l Graphic Trcnd Blorv Count Dry Densit-v Penetration Resistance (Blorvs/6") @ 5 Southwest 1,4,5 3,4,8 6,t0,12 8,.3,1 I 5,1 0,1 3 4,6,7 79-8ll B Country Club Drivc, Bemruda Drurcs, CA 92203 Plpne 345- I 588 Fax 34 5-73 I 5 SAND WITH SIL'l': pale yellowish brown, medium dense, dry, fine to medium grained 'l otal Depth 3 L5 feet No Groundrvater Encountcred 20 t0 l5 25 30 3s 40 45 50 55 SM SILI'Y SAND: pale yellowish brown, loose, dry, fine to mediunr grained SP-SM SM SAND WI1'H SIL'l': pale yellowish brown, loose, dry, fine to medium grained SILTY SAND: pale ycllowish brown, medium dense, damp, fine to medium grained, lenses of sandy silt mcdiunr dcnse fine grained MI.SANDY SIL'l': palc yellowish brown, clcnse, dry, fine graincd, lenscs of silty sand SP.SN,I 85 98 97 87 89 t4 t4 II 4 60 i|.'l'. iltlti I a @ Earth Systems Southwest ?9-81I B Country Club Drivc, Bcnnuda Duncs, CA 92203 Phone 345- l r88 ljax 34 r-73 I 5 5 t0 l5 t2 20 t8 25 30 3s 40 45 50 55 'l otal Depth 5 I.5 lbct No Groundwater Flncountercd S anrple 1 ypel& o. a)a ri?Uoo!t- =Afr tr) z€ E a 0Ua Boring No: B-5 Projcct Nanrc: NWC f)unc Palms Rd. & Avc 48, La Quinta, CA Irilc Number: 09571-04 Boring Location: Sce Figure 2 Drilling Date: May t6,2006 Drilling Mcthod: 8" Hollow Stenr Auger Drill'lype: Williams CML, 55 w/Auto llammer Loggcd tly: Dirk Wiggins Description of Units Nolc: I'hc slralificalion lincs shorvn rcpresen( thc approximale boundary betrveen soil and/or rock types and the lransition nray be gradational. Pagc I of IPenetration Resi.stance (lllows/6")Graphic'lrcnrl Blorv C'ount l)ry Density >' ar) 4)qi l-.l o >.v o \oI o'. Erl 3E\!{Ea-oU SP-SM MI SAND WITH SILT: loose, dry, no recovery palc ycllowish brown, mcdium dcnsc, dry SANDY SILT: moderate yellowish brown, nlediu,n dense, dry to danrp, hne to medium grained pale to moderate ycllowi.sh brown, with fine to medium grained santl mcdium dcnse, no recovery nroist damp, rvith l'inc grained sand damp SP.SM SM SAND WI1'H SILT: pale yellowish brown, medium dense, dry, fine to medium grained SILTY SAND: pale to moderate yellowish brown, medium dense, dry, fine to mediurn grained SP.SM SAND WITH SILT: pale yellowish brown, dense, dry, fine to medium grained 4,6,8 3.7, r I 5,r0,t2 6,6,8 1,5,7 3,9,9 s,9,9 4,7,8 9,16,18 2,4,5 2,5,6 97 8.5 96 60 t @ Earth Systems Southwest 79-8ll B Country Chrb Drivc, Bcrmuda Duncs, CA 92203 Phone 345- I 588, Fax 345-73 1.5 5 l0 l5 20 25 30 35 40 45 50 55 q- p- 0,)o Sarnple Typc !j 6U oo-VL 6v) Penetration I{esistance (13lorvs/6") E-o E)rC') OOa3 coo x 'a Eoox o Boring No: 8-6 Pr<lject Namc: NWC Dunc Palms I{d. & Ave, 48, La Quintq CA Filc Nurnber: 09571-04 tsoring Location: See l,'igure 2 pS E=Ul L'59 FicAO(-) Drilling Date: May 16, 2006 Drilling Method: 8" Ilollorv Stcm Auger Drill Typc: Williams CME 55 rv/Auto Ilamrner Logged I3y: Dirk Wiggins Description of Units Notc: 'l'he slratilication lincs shorvn rcpre.sent the appro.rinlatc boundary bctrveen soil andlor rock lypcs and thc transition may be gradational. Pagc I of I Graphic'l'rend Blorv Count Dry Dcnsity SP-SM SAND WITH SILT: palc yellowish brown, Ioose, dry, fine to mediunr graincd tnediunr densc SM SP.SM SILTY SAND: pale yellowish brown, mediunt densc, dry, fine grained dry to damp, sand rvith silt lenses SAND WITI{ SILT: pale yellowish brorvn, densc, dry, finc to mcdium grained rnoist, poor l'ecovery mediurl dcnse I 1,,4,l8 2,4,4 3,6,8 5,6,l0 5,10,12 5,9,16 5,7,8 5,7,8 90 99 82 88 94 r3 4 1 ') 'Iotal Depth 39 lect No (ir oundwatcr Encoun tcred 60 3 Earth Systems 79-8ll B Counlry Club Drivc, IJcnnuda Duncs, CA 92203 Phorrc 345. I 58 Fax 34 5-73 I 5 @ Southwest 5 t0 ls 20 25 30 35 40 45 s5 50 Borine No: B-7 Pro.iecttrlarns; NWC Dunc Palrns Rd, & Avc. 48, La Quinra, CA File Number: 09571-04 Boring Location: Sec Figure 2 I)rilling l)atc: May 16,2006 I)rilling Method: 8" Hollorv Stcrn Augcr DrillTypc: Williarns CtvlE 55 rv/Auto l-larnrner Logged By: Dirk Wiggins Lt- 4)a cJ do -!/, t O ,CL!/6qz Sarnple 'l'vpe Penetratiorr llesislance (Blows/6") z.o E)rv) U)U(r) x at) (,) +r tsc-L'"A rOQ) o\ Ea €ELoU I)escription of Units Notc: The stralification lines shorvn rcpresent lhc approxin:ate boundary berween soil and/or rock rypcs and the transition nray be gradalional. Graplric'liend Blorv Counl Dry Density Page I of I SP SAND WITH SILT: pale yellowish brown, mediunr dense, dry, fine to rnedium grained SM SILTY SAND: pale yellowish brorvn, nredium dense, dry, fine grained SP.SM SAND WITH SILT: pale yellowish brorvn, ntediunr dense to dense, dry, fine to medium grained SM 2,4,6 5,7,I r 5,1 0,1 4 t0,t4,16 6,ll,t2 7,1 I,l I 9,1 4,1 5 7,1 3,1 5 7,12,10 4,10, l2 8fi 9t 92 90 82 3 ) 2 SILTY SAND: pale yellowish brorvn, dense, dry, fine to rnedium grained, trace coarse grained ftne grained 'l'otal Depth 49 feet No Groundrvater Ertcountercd I I 60 @ Earth Systems 5 Southwest 3,6,9 3,6,7 5,10,1 I 7,10,12 ll,l7 ,22 7,18,17 5,10,1 3 6, I 1,9 30 l0 t5 20 25 35 40 45 55 50 79-81I B Country Club Drivc, Bcnrrrrda Drrnes, CA 92203 Phonc 345- t 58 Fax 34 5-73 r 5 -jl:- E o.|l)o Samplc I'ype,..r .d()rr-A ii\!l6qZ 6€ E)\(r) Boring No: B-8 Projcct Namc: NWC Drrne Palms t{d. & Ave. 48, La euinta, CA F ilc Numbcr: 09571-04 Boring Location: See Figure 2 Penetrati<ln Resistance (BIorvV6") a(Ja U) 0) (s'n(Jl-. O Lo ,S E='59 20() Drilling Date: May 15,2006 l)rilling Method: 8" Iltrllorv Srcm Augcr Drill'lype: Williams CMti 55 w/Auro Ilammcr Logged By: Dirk Wiggins Description of Units Note: Thc stratitication lincs shown represent the approxinralc boundary behvccn soil and/or rock types and the transilion nray bc gradational. Page I of I Craphic'frend Blow Counl Dry Density SAND WI'I'H SIL'l': pale yellowish brorvn, rnedium dcnse, dry, fine to nrcdiunt grained SILI'Y SAND: pale ycllowish brown, mcdium dense, dry, very fine to fine grained SIL'IY SAND: pale ycllowish brown, dense, dry, fine to nrcdiunr grained SM SILI'Y SAND; pale yellowish brown, dense, dry, fitte to nrediunr grained S P-SI\' 88 SM 9-1SM 9l 86 89 2 7 I 2 I 'lirtal Depth 41.5 feet No Groundwatcr Hncuuntered 60 :.[ ' :l; I ';l, '.l. .:[. i'l'i ,l a APPENDIX B Laboratory Test Results EARTH SYSTEMS SOUTIIWES'T ! \*.1 *h* i\'' , tJ t'' ; *. r* t*i' -',F; !? E\*;lvl : ,.13; =* -' i **a*.1\t* t* $ ffir* \.il $ h{t \.fr,e Ll H{ $ H tf, "t!r\Ll H frrf'r* \. H ffi $r \.t l I F ilt T I E a File No. : 09571 -04 July I 3, 2006 Lab No.: 06-0281 UNIT DENSITIES AND MOISTURE CONTENT ASrM Dzs37 & D22t6 Job Narne: NWC Dune Pahns & Ave 48, LQ, CA BI BI BI BI 5 t0 l5 20 88 92 89 1 4 3 l0 SM SM SM SM 82 ts2 B2 2.5 7.5 12.s 85 86 88 2 6 2 SP-SM SP.SM SP.SM B3 B3 B3 B3 B3 ts3 5 l0 l5 20 25 30 92 90 100 92 92 97 3 4 3 4 6 2 SP-SM SP.SM SP-SM SP.SM SM SP-SM B4 R4 B4 B4 B4 5 t0 l5 20 25 98 97 87 85 89 I 14 t4 4 il SP.SM SP-SM SM SM ML R5 B5 B5 l0 l5 20 96 97 85 I t2 l8 SP-SM ML ML Sarnple Location Depth (feet) Unit Dry Density (pcf) Moisture Content (%) USCS Group Symbol EARTH SYSTEMS SOUTHWEST { F ile No. : 09571 -04 Lab No.: 06-02 8 I UNIT DENSITIES AND MOISTURE CONTENT July I 3, 2006 AS]'M D2937 & D2216 Job Name: NWC Dune Palms & Ave 48, LQ, (-lA B6 B6 B6 B6 B6 B6 2.5 7.5 12.5 17.5 22.5 27 .5 82 88 90 94 99 I 3 4 2 l3 2 SP.SM SP-SM SM SM SM SP-SM B7 B7 87 B7 B7 2,5 7,5 12.5 17.5 22.5 90 82 86 91 SP SP SM SM SM I I aJ 2 2 92 B8 B8 B8 B8 B8 5 l0 l5 20 25 93 86 88 89 93 2 7 1 ') I SP.SM SP.SM SP.SM SM SM Sample Location Depth (feet) Unit Dty Density (pcf) Moisttrre Content (%) USCS Group Symbol EARTH SYS'TEMS SOUTHWEST p { F-ile No. : 09571 -04 Job Name: NWC Dune Palms &, Ave 48, LQ, CA Lab Number: 06-0281 AMOUNT PASSING NO. 2OO SIEVE July 13,2006 ASTIvT D II40 Sample Location Deptlr (1bet) Fines Content (%) USCS Group Symbol BI B4 B5 B6 87 B8 l5 25 l5 12.5 2,5 20 2l 67 70 46 4 42 SM ML ML SM SP SM EARTH SYSTEMS SOUTI{WEST' a t File No. : 09571 -04 July I 3,2006 Lab No.: 06-0281 PARTICLE SIZE ANALYSIS ASTM D-422 Job Name: NWC Dune Palms & Ave 48, Le, CA Sample ID: Bl @ l-4 Feet Description: Brown Silty Sand (SM) Sieve Percent Size Passing t-t/2" 1" 3/4" l12" 318" #4 #8 #16 #30 #s0 #100 #200 r00 100 100 r00 r00 100 t00 99 98 94 73 4l 7o Gravel: 0 '% Sand: 59 % Silt: 3I o/o Clay (3 micron): I0 (CIay content by short hydrometer rnethod) 100 90 80 70 .Eo 60 tht^6tsotr0) C) &40 30 20 l0 0 r 0.1 Particle Size ( rnm) I i I i -v- I ( )l 100 r0 EARTH SYSTEMS SOUTIIWEST 0,0 r 0,00 r F a File No. : 09571-04 Lab No, : 06-02 8 I PARTICLE SIZE ANALYSIS July I 3,2A06 ASTM D-422 Job Nanre: NWC Dune Palms & Ave 48, L,Q, CA Sample II); 84 (A L4 Feet Description: Brown Silty Sand (SM) Sieve Percelnt Size Passing t-U2" I'' 3/4" l12" 3/8" #4 #8 #16 #30 #50 # 100 #204 r00 100 I00 100 t00 100 100 100 I00 93 57 19 7u Gravcl: 0 o/u Sand: 8l % Silt: 14 o/o Clay (3 micron): 5 (Clay content by sh<lrt hydrorneter rnethod) t00 90 80 70 960,6 tt(! tso 0)g &qo 30 20 IO 0 I 0.t Particle Size ( rnrn) r00 i0 EARTH SYSTEMS SOUTHWEST 0.01 0.00 r I { i I \ i,,l