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04-7587 (OFC) Geotechnical Report— s d Earth Systems 1 1 • �� Southwest 1 1 r � I � v E 1 � titi t� i t ;CITY OF LA QUINTA BUILDING & SAFETY DEPT. APPROVED FOR CONSTRUCTION ID AT1s/014111 BY 4P Consulting Engineers andGeologists KELLY PACIFIC CONSTRUCTION 100 DRAKES LANDING ROAD, SUITE 105 GREENBRAE, CALIFORNIA 94904 REVISED GEOTECHNICAL ENGINEERING REPORT PROPOSED COMMERCIAL BUILDING LOT 6 OF DESERT CLUB #1 SOUTHWEST CORNER OF DESERT CLUB DRIVE AND CALLE BARCELONA LA QUINTA, CALIFORNIA November 22, 2004 Revised December 8, 2004 © 2004 Earth Systems Southwest Unauthorized use or copying of this document is strictly prohibited without the express written consent of Earth Systems Southwest. File No.: 09875-01 04-11-733R i I' � I Earth Systems �i Southwest December 8, 2004 Kelly Pacific Construction 100 Drakes Landing Road, Suite 105 Greenbrae, California 94904 Attention: Mr. James Kelly Project: Proposed Commercial Building, Lot 6 of Desert Club #1 Southwest Corner of Desert Club Drive and Calle Barcelona La Quinta, California Subject: Revised Geotechnical Engineering Report 79-811 B Country Club Drive Indio, CA 92203 (760)345-1588 (800)924-7015 FAX (760) 345-7315 File No.: 09875-01 04-11-733R ' Dear Mr. Kelly: We take pleasure in presenting this revised geotechnical engineering report prepared for the ' proposed commercial building to be located on Lot 6 of Desert Club #1, at the southwest corner of Desert Club Drive and Calle Barcelona, in the City of La Quinta, California. This report presents our findings and recommendations for site grading and foundation design, incorporating the information provided to our office. The site is suitable for the proposed development, provided the recommendations in this report are followed in design and construction. In general, the upper soils should be compacted to improve bearing capacity and reduce the potential for differential settlement. The site is subject to moderate ground motion from the San Andreas fault. This report should stand as a whole and no part of the report should be excerpted or used to the exclusion of any other part. This report completes our scope of services in accordance with our agreement, dated September 23, 2004. Other services that may be required, such as plan review and grading observation, are additional services and will be billed according to our Fee Schedule in effect at the time services 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 provide our professional services. Please contact our office if there are any questions or comments concerning this revised report or its recommendations. Respectfully su aFEss/Dti EARTH SYS T 1 c C7 3 C 38 3 E 38234 m Q EXP. 03/31/05 XM Craig S. Hill CE 38234 A A CM - FDF OF CAI�FD SER/csh/reh Distribution: 6/Kelly Pacific Construction 2/Kristi Hanson Architects, Inc. 1/RC File; 21131) File 4 I I EARTH SYSTEMS SOUTHWEST I TABLE OF CONTENTS Page EXECUTIVE SUMMARY............................................................................:..............ii Section 1 INTRODUCTION...........................................................................................1 1.1 Project Description............................................................................................1 1.2 Site Description.................................................................................................1 1.3 Purpose and Scope of Work..............................................................................2 Section 2 METHODS OF INVESTIGATION...............................................................3 2.1 Field Exploration............................................................................................... 3 2.2 Laboratory Testing.............................................................................................3 Section3 DISCUSSION...................................................................................................4 3.1 Soil Conditions..................................................................................................4 3.2 Groundwater...................................................................................................... 4 3.3 Geologic Setting................................................................................................4 3.4 Geologic Hazards...............................................................................................5 3.4.1 Seismic Hazards....................................................................................5 3.4.2 Secondary Hazards................................................................................6 3.4.3 Site Acceleration and Seismic Coefficients...........................................7 Section 4 CONCLUSIONS..............................................................................................9 Section 5 RECOMMENDATIONS..............................................................................10 SITE DEVELOPMENT AND GRADING.................................................................10 5.1 Site Development — Grading...........................................................................10 5.2 Excavations and Utility Trenches.................................................................... l l 5.3 Slope Stability of Graded Slopes..................................................................... l l STRUCTURES............................................................................................................12 5.4 Foundations.....................................................................................................12 5.5 Slabs-on-Grade................................................................................................13 5.6 Mitigation of Soil Corrosivity on Concrete.....................................................14 5.7 Seismic Design Criteria...................................................................................14 Section 6 LIMITATIONS AND ADDITIONAL SERVICES....................................16 6.1 Uniformity of Conditions and Limitations......................................................16 6.2 Additional Services..........................................................................................17 REFERENCES..........................................................................................................18 APPENDIX A Figure 1 — Site Location Map Figure 2 — Boring Location Map Table 1 — Fault Parameters Terms and Symbols used on Boring Logs Soil Classification System Logs of Borings APPENDIX B Laboratory Test Results EARTH SYSTEMS SOUTHWEST i ii ' EXECUTIVE SUMMARY Earth Systems Southwest has prepared this executive summary solely to provide a general ' overview of the report. The report itself should be relied upon for information about the findings, conclusions, recommendations, and other concerns. The site is located on Lot 6 of Desert Club #1, at the southwest corner of Desert Club Drive and Calle Barcelona, in the City of La Quinta, California. The proposed development will consist of a commercial building. We understand that the, proposed structure will be of wood -frame and stucco construction supported with perimeter wall . foundations and concrete slabs -on -grade constructed at or close to existing grade elevations. The proposed project may be constructed as planned, provided that the recommendations 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 utility installation, and concrete driveway and sidewalks placement. Based on the non-uniform nature and hydrocollapse potential of the near surface soils, remedial site grading is recommended to provide uniform support for the foundations. 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 proposed structures. The project site is located in the highly seismic Southern California region within the influence of several fault systems that are considered to be active or potentially active. The site is located in Seismic Zone 4 of the 2001 California Building Code (CBC). Structures should be designed in accordance with the values and parameters given within• the CBC. The seismic design parameters are presented in the following table and within the report. EARTH SYSTEMS SOUTHWEST [I 11 SUMMARY OF RECOMMENDATIONS Des)gn Item , Recommended Parameter 2 r{y ��{Reference. Sectiyon No(((yyyf`y� Foundations Allowable Bearing Pressure Continuous wall footings 1,500 psf 5.4 Pad (Column) footings 2,000 psf Foundation Tye Spread Footing 5.4 Bearing Materials Engineered fill Allowable Passive Pressure 250 pcf 5.4 Allowable Coefficient of Friction 0.35 5.4 Soil Expansion Potential Very low EI<20 3.1 Geologic and Seismic Hazards Liquefaction Potential Negligible 3.4.2 Significant Fault and Magnitude San Andreas, M7.7 3.4.3; 5.7 Fault Type A 3.4.3; 5.7 Seismic Zone 4 3.4.3; 5.7 Soil Profile Tye SD 3.4.3; 5.7 Near -Source Distance 12.8 km 3.4.3; 5.7 Near Source Factor, NA 1.00 3.4.3; 5.7 Near Source Factor, Nv 1.09 3.4.3; 5.7 Slabs Building Floor Slabs On engineered fill 5.5 Modulus of Subgrade Reaction 200 pci 5.5 Existing Site Conditions Existing Fill N/A Soil Corrosivity low sulfates low chlorides 5.6 Groundwater Depth Presently >100 feet 3.2 Estimated Fill and Cut (excludes over -excavation) < 3 feet — cuts and fills 1.1 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. EARTH SYSTEMS SOUTHWEST December 8, 2004 1 File No.: 09875-01 'REVISED GEOTECHNICAL 04-11-733R ENGINEERING REPORT ' PROPOSED COMMERCIAL BUILDING LOT 6 OF DESERT CLUB #I SOUTHWEST CORNER OF ' DESERT CLUB DRIVE AND CALLE BARCELONA LA QUINTA, CALIFORNIA Section 1 INTRODUCTION 1.1 Project Description This revised geotechnical engineering report has been prepared for the proposed commercial building to be located on Lot 6 of Desert Club #1, at the southwest corner of Desert Club Drive and Calle Barcelona, in the City of La Quinta, California. ' The proposed commercial building may be a single- or multi -story structure constructed at or close to existing grade elevations. We understand that the proposed structure will be of wood - frame and stucco construction and will be supported by conventional shallow continuous or pad footings. Site development will include clearing and grubbing of vegetation, site grading, building pad preparation, underground utility installation, and concrete driveway and sidewalks placement. Based on existing site topography and ground conditions, site grading is expected to consist of minimal cuts and fills. We used maximum column loads of 20 kips and a maximum wall loading of 2 kips per linear foot as a basis for the foundation recommendations. All loading is assumed to be dead plus actual live load. If actual structural loading exceeds these assumed values, we would need to reevaluate the given recommendations. 1.2 Site Description The proposed commercial building is to be constructed on a vacant lot at the southwest corner of Desert Club Drive and Calle Barcelona in the City of La Quinta, California. The site location is shown on Figure 1 in Appendix A. The project site consists of a rectangular -shaped parcel that has been previously rough graded or leveled in conjunction with development of the surrounding tract. The proposed building site is relatively flat and level with adjacent properties at an elevation of. approximately 50 feet above mean sea level. The site is relatively void of any vegetation, with the exception of several palm ' trees along the western lot boundary. The site is bound by Calle Barcelona to the north, Desert Club Drive to the east, an existing commercial building to the west, and a new commercial building under construction to the south. EARTH SYSTEMS SOUTHWEST December 8, 2004 2 File No.: 09875-01 ' 04-11-733R The history of past use and development of the property was not investigated as part of our scope ' of services. No evidence of past development was observed on the site during our reconnaissance. Nonetheless, some previous development of the site is possible. Buried remnants, such as old foundations, slabs, or septic systems, may exist on the site. There may be underground utilities near and within the building area. These utility lines may include, but are not limited to, domestic water, electric, sewer, telephone, cable, and irrigation lines.' 1.3 Purpose and Scope of Work ' The purpose for our services was to evaluate the site soil conditions and to provide professional opinions and recommendations regarding the proposed development of the site. The scope of work included the following: ➢ A general reconnaissance of the site. ' ➢ Shallow subsurface exploration by drilling, four exploratory borings to depths ranging from 14 to 21.5 feet below existing grade. ➢ Laboratory testing of selected soil samples obtained from the exploratory borings. ➢ A review of selected published technical literature pertaining to the site and previous geotechnical reports prepared for similar projects in the vicinity. ➢ An engineering analysis and evaluation of the acquired data from the exploration and testing programs. ➢ A summary of our findings and recommendations in this written report. ' This report contains the following: ➢ Discussions on subsurface soil and groundwater conditions. ➢ Discussions on regional and local geologic conditions. ➢ Discussions on geologic and seismic hazards. ➢ Graphic and tabulated results of laboratory tests and field studies. ' ➢ Recommendations regarding: • Site development and grading criteria. • Excavation conditions and buried utility installations. 1 • Structure foundation type and design. • Allowable foundation bearing capacity and expected total and differential settlements. • Concrete slabs -on -grade. ' Mitigation of the potential corrosivity of site soils to concrete and steel reinforcement. • Seismic design parameters. ' Not Contained in This Report: Although available through Earth Systems Southwest, the current scope of our services does not include: ➢ A corrosive study to determine cathodic protection of concrete or buried pipes. ' ➢ An environmental assessment. ➢ An investigation for the presence or absence of wetlands, hazardous or toxic materials in the soil, surface water, groundwater, or air on, below, or adjacent to the subject property. ' EARTH SYSTEMS SOUTHWEST December 8, 2004 3 File No.: 09875-01 04-11-733R Section 2 1 METHODS OF INVESTIGATION 2.1 Field Exploration Four exploratory borings were drilled to depths ranging from 14 to 21.5 feet below the existing ground surface to observe the soil profile and to obtain samples for laboratory testing. The borings were drilled on October 7, 2004 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 j location map, Figure 2, in Appendix A. The locations shown are approximate, established by ' pacing and sighting from existing topographic features. Samples were obtained within the test borings using a Standard Penetration (SPT) sampler ' (ASTM D 1586) and a Modified California (MC) ring sampler (ASTM D 3550 with shoe similar to ASTM D 1586). The 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 diameter. The ' samples were obtained by driving the sampler with a 140 -pound hammer, manually activated by rope and cathead, dropping 30 inches in general accordance with ASTM D 1586. Recovered soil samples were sealed in containers and returned to the laboratory. Bulk samples were also obtained from auger cuttings, representing a mixture of soils encountered at the depths noted. The final logs of the borings represent our interpretation of the 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 lines represent the approximate boundaries between soil types, although the transitions may be gradational. 2.2 Laboratory Testing ' Samples were reviewed along with field logs to select those that would be analyzed further. Those selected for laboratory testing include soils that would be exposed and used during grading and those deemed to be within the influence of the proposed structure. Test results are presented ' in graphic and tabular form in Appendix B of this report. The tests were conducted in general accordance with the procedures of the American Society for Testing and Materials (ASTM) or other standardized methods as referenced below. Our testing program consisted of the following: ➢ In-situ Moisture Content and Unit Dry Weight for the ring samples. ' ➢ Maximum density tests to evaluate the moisture -density relationship of typical soils encountered. ' ' ➢ Particle Size Analysis to classify and evaluate soil . composition. The gradation characteristics of selected samples were made by hydrometer and sieve analysis procedures. ' ➢ Consolidation (Collapse Potential) to evaluate the compressibility and hydroconsolidation (collapse) potential of the soil. ' ➢ Chemical Analyses (Soluble Sulfates and Chlorides, pH, and Electrical Resistivity) to evaluate the potential adverse effects of the soil on concrete and steel. ' EARTH SYSTEMS SOUTHWEST December 8, 2004 4 File No.: 09875-01 ' 04-11-733R Section 3 DISCUSSION 3.1 Soil Conditions The field exploration indicates that site soils consist generally of loose to dense, dry, interbedded Silty Sand and Sandy Silt (Unified Soil Classification System symbols of SM and ML). The I' boring logs provided in Appendix A include more detailed descriptions of the soils encountered. The soils are visually classified to be. in the very low expansion (EI < 20) category in accordance with Table 18A -1-B of the California Building Code. In and climatic regions, granular soils may have a potential to collapse upon wetting. Collapse (hydroconsolidation) may occur when the soluble cements (carbonates) in the soil matrix dissolve, causing the soil to densify from its loose configuration from deposition. Consolidation testing indicates approximately 1.3% collapse upon inundation and collapse is therefore considered a moderate site risk. The hydroconsolidation potential is commonly mitigated by ' recompaction of a zone beneath building pads. Fine particulate matter (PM10) can create an air quality hazard if dust is blowing. Watering the surface, planting grass or landscaping, or placing hardscape normally mitigates this hazard. 3.2 Groundwater ' Free groundwater was not encountered in the borings during exploration. The depth to groundwater in the area is believed to be greater than 100 feet based on 1986 water well data ' obtained from the USGS Water Resources Bulletin 91-4196. Groundwater levels may fluctuate with precipitation, irrigation, drainage, and regional pumping from wells. Groundwater should not be a factor in design or construction at this site. 3.3 Geologic Setting ' Regional Geology: 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 ' extends approximately 180 miles from the San Gorgonio Pass to the Gulf of California. Much of this depression in the area of the Salton Sea is below sea level. ' The Coachella Valley forms the northerly part of the Salton Trough. The Coachella Valley contains a thick sequence of sedimentary deposits that are Miocene to recent in age. Mountains ' surrounding the Coachella Valley include the Little San Bernardino Mountains on the northeast, foothills of the San Bernardino Mountains on the northwest, and the San Jacinto and Santa Rosa Mountains on the southwest. These mountains expose primarily Precambrian metamorphic and Mesozoic granitic rocks. The San Andreas fault zone within the Coachella Valley consists of the Garnet Hill fault, the Banning fault, and the Mission Creek fault that traverse along the northeast margin of the valley. EARTH SYSTEMS SOUTHWEST i December 8, 2004 5 File No.: 09875-01 ' 04-11-733R Local Geology: The project site lies within the La Quinta cove at about 50 feet above mean sea ' level in the central part of the Coachella Valley. The sediments within the lower part of the cove consist of fine- to coarse-grained sands with interbedded clays and silts of aeolian (wind-blown), lacustrine (lake -bed), and alluvial (water -laid) origin. ' 3.4 Geologic Hazards t Geologic hazards that may affect the region include seismic hazards (ground shaking, surface fault rupture, soil liquefaction, and other secondary earthquake -related hazards), slope instability, flooding, ground subsidence, and erosion. A discussion follows on the specific hazards to this ' site. 3.4.1 Seismic Hazards Seismic Sources: Several active faults or seismic zones lie within 62 miles (100 kilometers) of the project site as shown on Table 1 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 (Mmax) listed is from published geologic information available for each fault (Cao et al., CGS, 2003). The Mum corresponds to the maximum earthquake believed to be tectonically possible. Surface Fault Rupture: The project site does not lie within a currently delineated State of tCalifornia, Alquist-Priolo Earthquake Fault Zone (Hart, 1997). Well -delineated fault lines cross through this region as shown on California Geological Survey (CGS) maps (Jennings, 1994). Therefore, active fault rupture is unlikely to occur at the project site. While fault rupture would ' most likely occur along previously established fault traces, future fault rupture could occur at other locations. ' Historic Seismicity: Six historic seismic events (5.9 M or greater) have significantly affected the Coachella Valley in the last 100 years. They are as follows: ' • Desert Hot Springs Earthquake — On December 4, 1948, a magnitude 6.5 ML (6.OMw) earthquake occurred east of Desert Hot Springs. This event was strongly felt in the Palm t Springs area. • Palm Springs Earthquake — A magnitude 5.9 ML (6.2Mw) earthquake occurred on July 8, 1986 in the Painted Hills, causing minor surface creep of the Banning segment of the San Andreas fault. This event was strongly felt in the Palm Springs area and caused structural ' damage, as well as injuries. • Joshua Tree Earthquake — On April 22, 1992, a magnitude 6.1 ML (6.1 Mw) earthquake ' occurred in the mountains 9 miles east of Desert Hot Springs. Structural damage and minor injuries occurred in the Palm Springs area as a result of this earthquake. • Landers and Big Bear Earthquakes — Early on June 28, 1992, a magnitude 7.5 Ms (7.3Mw) earthquake occurred near Landers, the largest seismic event in Southern California for 40 years. Surface rupture occurred 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 Palm Springs area. I EARTH SYSTEMS SOUTHWEST December 8, 2004 6 File No.: 09875-01 ' 04-11-733R • Hector Mine Earthquake — On October 16, 1999, a magnitude 7.1 MW 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 been reported in the Coachella Valley. ' Seismic Risk: While accurate earthquake predictions are not possible, various agencies have conducted statistical risk analyses. In 2002, the California Geological Survey (CGS) and the United States Geological Survey (USGS) 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 California Earthquake Probabilities (WGCEP, 1995) estimated a 22% conditional probability that a magnitude 7 or greater earthquake may occur between 1994 and ' 2024 along the Coachella segment of the San Andreas fault. The 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 each fault segment. The estimated characteristic earthquake is magnitude 7.7 for the t 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 occurred about 1690 AD, based on dating by the USGS near Indio (WGCEP, 1995). This segment has also ruptured on about 1020, ' 1300, and 1450 AD, with an average recurrence interval of about 220 years. The San Andreas fault may rupture in multiple segments, producing a higher magnitude earthquake. Recent paleoseismic studies suggest that the San Bernardino Mountain Segment to the north and the ' Coachella Segment may have 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 seiches are considered negligible at this time. ' Soil Liquefaction: Liquefaction is the loss of soil strength from sudden shock (usually earthquake shaking), causing the soil to become a fluid mass. In general, for the effects of liquefaction to be manifested at the surface, groundwater levels must be within 50 feet of the t ground surface and the soils within the saturated zone must also be susceptible to liquefaction. The potential for liquefaction to occur at this site is considered negligible because the depth of groundwater beneath the site exceeds 50 feet. No free groundwater was encountered in our ' exploratory borings. In addition, the project does not lie within the Riverside County designated liquefaction hazard zone. ' Ground Subsidence: The potential for seismically induced ground subsidence is considered to be slight to moderate at the site. Dry sands tend to settle and densify when subjected to strong earthquake shaking. The amount of subsidence is dependent on relative density of the soil, ' ground motion, and earthquake duration. Uncompacted fill areas may be susceptible to seismically induced settlement. ' Slope Instability: The site is relatively flat. Therefore, potential hazards from slope instability, landslides, or debris flows are considered negligible. ' EARTH SYSTEMS SOUTHWEST i L December 8, 2004 7 File No.: 09875-01 04-11-733R Flooding: The project site does not lie within a designated FEMA 100 -year flood plain. The project site may be in an area where sheet flooding and erosion could occur. If significant changes are proposed for the site, appropriate project design, construction, and maintenance can minimize the site sheet flooding potential. 3.4.3 Site Acceleration and Seismic Coefficients Site Acceleration: The potential intensity of ground motion may be estimated by the horizontal peak ground acceleration (PGA), measured in "g" forces. Included in Table 1 are deterministic estimates of site acceleration from possible earthquakes at nearby faults. Ground motions are dependent primarily on the earthquake magnitude 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 these 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 PGA alone is an inconsistent scaling factor to compare to the CBC Z factor and is generally a poor indicator of potential structural damage during an earthquake. Important factors influencing the structural performance are the duration and frequency of strong ground motion, local subsurface conditions, soil -structure interaction, and structural details. The following table provides the probabilistic estimate of the PGA taken from the 2002 CGS/USGS seismic hazard maps. Estimate of PGA from 2002 CGS/USGS Probabilistic Seismic Hazard Mans Risk Equivalent Return I Period (years) PGA (g) t 10% exceedance in 50 years 475 0.49 ' Notes: 1. Based on a soft rock site, SB/C, and soil amplification factor of 1.0 for Soil Profile Type So. 2001 CBC Seismic Coefficients: The California Building Code (CBC) seismic design criteria ' are based on a Design Basis Earthquake (DBE) that has an earthquake ground motion with a 10% probability of occurrence in 50 years. The PGA estimate given above is provided for ' information on the seismic risk inherent in the CBC design. The seismic and site coefficients given in Chapter 16 of the 2001 California Building Code are provided in Section 5.7 of this report and below. 7 ' EARTH SYSTEMS SOUTHWEST December 8, 2004 8 File No.: 09875-01 04-11-733R 2001 CBC Seismic Coefficients for Chapter 16 Seismic Provisions Reference Seismic Zone: 4 Figure 16-2 Seismic Zone Factor, Z: 0.4 Table 16-I Soil Profile Type: SD Table 16-J Seismic Source Type: A Table 16-U Closest Distance to Known Seismic Source: 12.8 km = 8.0 miles (San Andreas fault) Near Source Factor, Na: 1.00 Table 16-S Near Source Factor, Nv: 1..09 Table 16-T Seismic Coefficient, Ca: 0.44 = 0.44Na Table 16-Q Seismic Coefficient, Cv: 0.70 = 0.64Nv Table 16-R Seismic Hazard Zones: The site does not lie within a liquefaction, landslide, or fault rupture hazard area or zone established by the 2002 Riverside County General Plan. Riverside County has not been mapped by the California Seismic Hazard Mapping Act (Ca. PRC 2690 to 2699). a . EARTH SYSTEMS SOUTHWEST December 8, 2004 9 File No.: 09875-01 04-11-733R Section 4 CONCLUSIONS The following is a summary of our conclusions and professional opinions based on the data obtained from a review of selected technical literature and the site evaluation. General: ➢ From a geotechnical perspective, the site is suitable for the proposed development, provided the recommendations in this report are followed in the design and construction of this project. Geotechnical Constraints and Mitigation: ➢ The primary geologic hazard is severe ground shaking from earthquakes originating on nearby faults. A major earthquake above magnitude 7 originating on the local segment of the San Andreas fault zone would be the critical seismic 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. ➢ The project site is in seismic Zone 4, is of soil profile Type SD, and is about 12.8 km from a Type A seismic source as defined in the California Building Code. A qualified professional should design any permanent structure constructed on the site. The minimum seismic design should comply with the 2001 edition of the California Building Code. ➢ Ground subsidence from seismic events or hydroconsolidation is a potential hazard in the Coachella Valley area. Adherence to the grading and structural recommendations in this report should reduce potential settlement problems from seismic forces, heavy rainfall or irrigation, flooding, and the weight of the intended structures. ➢ The soils are susceptible to wind and water erosion. Preventative measures to reduce 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). ➢ Other geologic hazards, including fault rupture, liquefaction, seismically induced flooding, and landslides, are considered low or negligible on this site. ➢ The upper soils were found to be relatively loose to medium dense and are unsuitable in ' their present condition to support structures, fill, and hardscape. The soils within the building and structural areas will require moisture conditioning, over -excavation, and ' recompaction to improve bearing capacity and reduce settlement from static loading. Soils can be readily cut by normal grading equipment. ' EARTH SYSTEMS SOUTHWEST i December 8, 2004 Section 5 ' RECOMMENDATIONS 10 SITE DEVELOPMENT AND GRADING 5.1 Site Development — Grading File No.: 09875-01 04-11-733R ' A representative of Earth Systems Southwest (ESSW) should observe site clearing, grading, and the bottoms of excavations before placing fill. Local variations in soil conditions may warrant increasing the depth of recompaction and over -excavation. Clearing and Grubbing: At the start of site grading, existing vegetation, non -engineered fill, construction debris, trash, and abandoned underground utilities should be removed .from the proposed building, structural, and pavement areas. The surface should be stripped of organic growth and removed from the construction area. Areas disturbed during clearing should 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 Management District (SCAQMD). Building Pad Preparation: Because of the relatively non-uniform and under -compacted nature of the majority of the site soils, we recommend recompaction of soils in the building area. The existing surface soils within the building pad and foundation areas should be over -excavated to a minimum of 3 feet below existing grade or a minimum of 2 feet below the footing level (whichever is lower). The over -excavation should extend for 5 feet beyond the outer edge of exterior footings. The bottom of the sub -excavation should be scarified, moisture conditioned, and recompacted to at least 90% relative compaction (ASTM D 1557) for an additional depth of 1 foot. Although not anticipated, if signs of previous development are evident at the bottom of the over -excavation, the depth and lateral extent will need to be increased to expose undisturbed native soil. These recommendations are intended to provide a minimum of 4 and 3. feet of moisture conditioned and compacted soil beneath the floor slabs and footings, respectively. Auxiliary Structures Subgrade Preparation: Auxiliary structures such as garden or retaining walls should have the foundation subgrade prepared similar to the building pad recommendations given above. The lateral extent of the over -excavation needs to extend only 2 feet beyond the face of the footing. Subgrade Preparation: In areas to receive fill, pavements, or hardscape, the subgrade should be scarified, moisture conditioned, and compacted to at least 90% relative compaction (ASTM D 1557) for a depth of 1 foot below finished subgrades. Compaction should be verified by testing. Engineered Fill Soils: The native 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 should be placed in maximum 8 -inch lifts (loose) and compacted to at least 90% relative compaction (ASTM D 1557) near its optimum moisture content. Compaction should be verified by testing. EARTH SYSTEMS SOUTHWEST i December 8, 2004 11 File No.: 09875-01 04-11-733R Imported fill soils (if needed) should be non -expansive, granular soils meeting the 1 USCS classifications of SM, SP -SM, or SW -SM with a maximum rock size of 3 inches and 5 to 35% 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 prequalified 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. Shrinkage: The shrinkage factor for earthwork is expected to range from 15 to 20 percent for the upper excavated or scarified site soils. This estimate is based on compactive effort to achieve 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 removal 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% for 5 feet minimum) to prevent ponding and subsequent saturation of the foundation soils. Gutters and ' downspouts should be considered as a means to convey water away from foundations if adequate drainage is not provided. Drainage should be maintained for paved areas. Water should not ' pond on or near paved areas. 5.2 Excavations and Utility Trenches. ' Excavations should be made in accordance with CalOSHA 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 1.5:1 (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. ' Utility 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 property may be backfilled with native soils compacted to a minimum of 90% relative compaction. Backfill ' operations should be observed and tested to monitor compliance with these recommendations. 5.3 Slope Stability of Graded Slopes Unprotected, permanent graded slopes should not be steeper than 3:1 (horizontal:vertical) to reduce wind and rain erosion. Protected slopes with ground cover may be as steep as 2:1. ' However, maintenance with motorized equipment 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). I EARTH SYSTEMS SOUTHWEST i December 8, 2004 12 File No.: 09875-01 04-11-733R STRUCTURES In our professional opinion, structure foundations can be supported on shallow foundations bearing on a zone of properly prepared and compacted soils placed as recommended in Section 5.1. The recommendations that follow are based on very low expansion category soils. 5.4 Foundations Footing 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 minimum footing depth of 12 inches below lowest adjacent grade should be maintained. 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. ConventionalSpread Foundations: Allowable soil bearing pressures foundations bearing on recompacted soils as described in Section 5.1. pressures are net (weight of footing and soil surcharge may be neglected). are given below for Allowable bearing ➢ Continuous wall foundations, 12 -inch minimum width and 12 inches below grade: 1500 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 be used up to a maximum value of 2500 psf. ➢ Isolated pad foundations, 2 x 2 foot minimum in plan and 18 inches below grade: 2000 psf for dead plus design live 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 2500 psf. A one-third ('/3) increase in the bearing pressure may be used when calculating resistance to wind or seismic loads. The allowable bearing values indicated are based on the anticipated maximum loads stated in Section 1.1 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 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 engineer. Expected Settlement: Estimated total static settlement should. be less than 1 inch, based on footings founded on firm soils as recommended. Differential settlement between exterior and interior bearing members should be less than '/z inch, expressed in a post -construction angular distortion ratio of 1:480 or less. 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 may be used. An allowable passive equivalent fluid EARTH SYSTEMS SOUTHWEST i December 8, 2004 13 File No.: 09875-01 ' 04-11-733R pressure of 250 pcf may also be used. These values include a factor of safety of 1.5. Passive ' resistance and frictional resistance may be used in combination if the friction coefficient is reduced by one-third. A one-third ('/3) 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 compacted soil placed in accordance with Section 5.1 of this report. ' Vapor Retarder: In areas of moisture sensitive floor coverings, an appropriate vapor retarder should be installed to reduce moisture transmission from the subgrade soil to the slab. For these ' areas, an impermeable membrane (10 -mil thickness) should underlie the floor slabs. The membrane should be covered with 2 inches of sand to help protect it during construction and to aid in concrete curing. The sand should be lightly moistened just prior to placing the concrete. 1 Low -slump concrete should be used to help reduce the potential for concrete shrinkage. The effectiveness of the membrane is dependent upon its quality, the method of overlapping, its tprotection during construction, and the successful sealing of the membrane around utility lines. The following minimum slab recommendations are intended to address geotechnical concerns such as potential variations of the subgrade and are not to be construed as superseding any structural design. ' Slab Thickness and Reinforcement: Slab thickness and reinforcement of slabs -on -grade are contingent on the recommendations of the structural engineer or architect and the expansion index of the supporting soil. Based upon our findings, a modulus of subgrade reaction of ' approximately 200 pounds per cubic inch can be used in concrete slab design for the expected very low expansion subgrade. t Concrete slabs and flatwork should be a minimum of 4 inches thick (actual, not nominal). We suggest that the concrete slabs be reinforced with a minimum of No. 3 rebars at 18 -inch centers, both horizontal directions, placed at slab mid -height to resist cracking. Concrete floor slabs may ' either be monolithically placed with the foundations or doweled after footing placement. The thickness and reinforcing given are not intended to supersede any structural requirements provided by the structural engineer. The project architect or geotechnical engineer should ' continually observe all reinforcing steel in slabs during placement of concrete to check for proper location within the slab. Control Joints: Control joints should be provided in all concrete slabs -on -grade at a maximum spacing of 36 times the slab thickness (12 feet maximum on -center, each way) as recommended by American Concrete Institute (ACI) guidelines. All joints should form approximately square ' patterns to reduce the potential for randomly oriented, contraction cracks. Contraction joints in the slabs should be tooled at the time of the pour or saw cut ('/4 of slab depth) within 8 hours of concrete placement. Construction (cold) joints should consist of thickened butt joints with ' '/z -inch dowels at 18 -inches on center or a thickened keyed joint to resist vertical deflection at the joint. All construction joints in exterior flatwork should be sealed to reduce the potential of I EARTH SYSTEMS SOUTHWEST i December 8, 2004 14 File No.: 09875-01 ' 04-11-733R moisture or foreign material intrusion. These procedures will reduce the potential for randomly ' oriented cracks, but may not prevent them from occurring. Curing and Quality Control: The contractor should take precautions to reduce the potential of ' 'curling of slabs in this and desert region using proper batching, placement, and curing methods. Curing is highly affected by temperature, wind, and humidity. Quality control procedures may be used, including trial batch mix designs, batch plant inspection, and on-site special inspection and ' testing. Typically, for this type of construction and using 2500 -psi concrete, many of these quality control procedures are not required. '5.6 Mitigation of Soil Corrosivity on Concrete Selected chemical analyses for corrosivity were conducted on soil samples from the project site as shown in Appendix B. The native soils were found to have a low sulfate ion concentration (56 ppm) and a low chloride ion concentration (30 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 Code does not require any special provisions for concrete for these low concentrations ' as tested. Normal concrete mixes may be used. A minimum 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 moderate potential for metal loss from electrochemical corrosion processes.. Corrosion protection of steel can be achieved by using epoxy corrosion inhibitors, asphalt coatings, cathodic protection, or encapsulating with densely consolidated concrete. The information provided above should be considered preliminary. These values can potentially ' change based on several factors, such as importing soil from another job site and the quality of construction water used during grading and subsequent landscape irrigation. ' Earth Systems does not practice corrosion engineering.. We recommend that a qualified corrosion engineer evaluate the corrosion potential on metal construction materials and concrete at the site to provide mitigation of corrosive effects, if further guidance is desired. '5.7 Seismic Design Criteria ' This site is subject to strong ground shaking due to potential fault movements along 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 the seismic coefficients given in the table below. ' EARTH SYSTEMS SOUTHWEST i December 8, 2004 15 File No.: 09875-01 ' 04-11-733R 2001 CBC Seismic Coefficients for Chapter 16 Seismic Provisions Seismic Zone: Seismic Zone Factor, Z: Soil Profile Type: Seismic Source Type: Closest Distance to Known Seismic Source Near Source Factor, Na: Near Source Factor, Nv: Seismic Coefficient, Ca: Seismic Coefficient, Cv: 4 0.4 SD A 12.8 km = 8.0 miles 1.00 1.09 0.44 = 0.44Na 0.70 = 0.64Nv Reference Figure 16-2 Table 16-I Table 16-J Table 16-U (San Andreas fault) Table 16-5 Table 16-T Table 16-Q Table 16-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 probabilistic seismic analysis should be conducted. The intent of the CBC 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 structural and nonstructural damage. A fundamental tenet of seismic design is that inelastic yielding is allowed to adapt to the seismic demand on the structure. In other words, damage is allowed. The CBC lateral force requirements should be considered a minimum design. The owner and the designer should evaluate the level of risk and performance that is acceptable. Performance based 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 verify that the design plans and good construction practices are followed. This is especially important for sites lying close to the major seismic sources. EARTH SYSTEMS SOUTHWEST December 8, 2004 16 File No.: 09875-01 ' 04-11-733R 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. Furthermore, our findings and recommendations are based on the assumption that soil -conditions do not vary significantly from those found at specific exploratory locations. Variations in soil or groundwater conditions could exist between and beyond the exploration points. The nature and ' extent of these variations may not become evident until construction. Variations in soil or groundwater may require additional studies, consultation, and possible revisions to our recommendations. Findings of this report are valid as of the issued date of the report. However, 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 report may be invalidated wholly or partially by changes outside our control. Therefore, this report is subject to review and should not be relied upon after a period of one year. ' In the event that any changes in the nature, design, or location of structures are planned, the conclusions and recommendations contained in this report shall not be considered valid unless the changes are reviewed and the conclusions of this report are 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 herein 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 verify that the general contractor and all subcontractors follow such recommendations. It is further understood that the owner or the owner's representative is responsible for submittal of this report 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 generally accepted geotechnical engineering practices in this locality at this time. No warranty or guarantee is express or implied. This report ' was prepared for the exclusive use of the Client and the Client's authorized agents. ESSW should be provided the opportunity for a general review of final 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 accorded the privilege of making this recommended review, we can assume no responsibility for misinterpretation of our ' recommendations. Although available through ESSW, the current scope of our services does not include an ' environmental assessment or an investigation for the presence or absence of wetlands, hazardous EARTH SYSTEMS SOUTHWEST i December 8, 2004 17 File No.: 09875-01 ' 04-11-733R or toxic materials in the soil, surface water, groundwater, or air on, below, or adjacent to the ' subject property. 6.2 Additional Services This 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 observations shall assume the responsibility of Geotechnical Engineer of Record. Construction monitoring and testing would be additional services provided by our firm. The costs of these, services are not included in our present fee arrangements, but can be obtained from our office. The recommended review, tests, and observations include, but are not necessarily _ limited to, the following: • Consultation during the final design stages of the project. g t radi • A review of the building and n plans to observe that recommendations of our re grading P 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. -000- Appendices as cited are attached and complete this report. 1 � I � I � I ' EARTH SYSTEMS SOUTHWEST December 8, 2004 18 File No.: 09875-01 04-11-733R REFERENCES Abrahamson, N., and Shedlock, K., editors, 1997, Ground motion attenuation relationships: Seismological Research Letters, v. 68, no. 1, January 1997 special issue, 256 p. American Concrete Institute (ACI), 1996, ACI Manual of Concrete Practice, Parts 1 through 5. I American Society of Civil Engineers (ASCE), 2003, Minimum Design Loads for Buildings and Other Structures, ASCE 7-02 California Geologic Survey (CGS), 1997, Guidelines for Evaluating and Mitigating Seismic Hazards in California, Special Publication 117. Cao, T, Bryant, W.A., Rowhandel, B., Branum. D., and Wills, C., 2003, The Revised 2002 California Probabilistic Seismic Haiard Maps, California Geologic Survey (CGS), June 2003. ' California Department of Water Resources, 1964, Coachella Valley Investigation, Bulletin No. 108, 146 pp. ' Envicom Corporation and the County of Riverside Planning Department, 1976, Seismic Safety and Safety General Plan Elements Technical Report, County of Riverside. ' Frankel, A.D., et al., 2002, Documentation for the 2002 Update of the National Seismic Hazard Maps, USGS Open -File Report 02-420. ' Hart, E.W., 1997, Fault -Rupture Hazard Zones in California: California Division of Mines and Geology Special Publication 42. ' International Code Council (ICC), 2002, California Building Code, 2001 Edition. Jennings, CW, 1994, Fault Activity Map of California and Adjacent Areas: California Division of Mines and Geology, Geological Data Map No. 6, scale 1:750,000. ' Petersen, M.D., Bryant, W.A., Cramer, C.H., Cao, T., Reichle, M.S., Frankel, A.D., Leinkaemper, J.J., McCrory, P.A., and Schwarz, D.P., 1996, Probabilistic Seismic Hazard 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 Riverside County General Plan — Hearing Draft. Rogers, T.H., 1966, Geologic Map of California - Santa Ana Sheet, California Division of Mines and Geology Regional Map Series, scale 1:250,000. Structural Engineers Association of California (SEAOC), 1996, Recommended Lateral Force Requirements and Commentary. IEARTH SYSTEMS SOUTHWEST December 8, 2004 19 File No.: 09875-01 04-11-733R Tokimatsu, K, and, Seed, H.B., 1987, Evaluation of Settlements in Sands Due To Earthquake Shaking, ASCE, Journal of Geotechnical Engineering, Vol. 113, No. 8, August 1987. Working Group on California Earthquake Probabilities, 1995, Seismic Hazards in Southern California: Probable Earthquakes, 1994-2024: Bulletin .of the Seismological Society of America, Vol. 85, No. 2, pp. 379-439. Wallace, R. E., 1990, The San Andreas Fault System, California: U.S. Geological Survey Professional Paper 1515, 283 p. 11 EARTH SYSTEMS SOUTHWEST I 0 APPENDIX A Figure 1 = Site Location Map Figure 2 — Boring Location Map Table 1 — Fault Parameters Terms and Symbols used on Boring Logs Soil Classification System Logs of Borings in ' EARTH SYSTEMS SOUTHWEST - V •iN"N' ' % . ..... .... ... . ....... ... ........ aid Q) 4 (3 0 !% i% 0 ,•, ''N{.Rt:a,. � '• '� f � �_.• q(s••aaa Yeas J � O C� ter • 50 Water Well •j1 II II II II Q: . ....... "to 00 Z DO 6 �oaaa�--,a_ � � LL-��--aa// �• , ::�::>c:: :� n.:.:►:a.—. aa.a).+.r:?.t •�Q�aL�i�' 1D�����-___-__-= .ttiieDt ii iv ra e)t •aY e. ........... :ao IAC = ��GD�b�t �• 8 i••traaa•et -1: 7 'Calle Barcelona---- :Ozj SITE r-1 41; Purn .... 41, r La Quinta- r�:, �l. -Ys iea 8 7 —64 Base Map: U.S,GS. 7.5 Minute Quadrangles, La Quinta, Calif. Figure 1 (1959, Photo Revised 1980) Site Location Map SWC Desert Club Drive & Calle Barcelona Lot 6, Desert Club #1 Scale: 1 2,000' La Qu*nta, California Earth Systems O 0 2,000' 4,000' I Southwest 12/08/04 1 File No.: 09875-01 116°18'12"W 564600 0 0 M Co N A M ti NQ O � O "t -to N o M N r1 M 564700 564800 116°18'2"W 0 0 M to N n M 564600 564700 564800 116°18'12" 6V 116018'2"W 0 25 50 100 150 200 250 Feet N Figure 2 LEGEND Boring Location Map SWC Desert Club Drive & Calle Barcelona Boring Location Lot 6 Desert Club #1 La Quinta California ® Project Area � Earth Systems Southwest Date: 12/08/04 File No.: 09875-01 i 7 7 I � I � I � I � I � I I I I I I I I I I I Lot 6 Desert Club # 1 Table 1 Fault Parameters & Deterministic Estimates of Mean Peak Ground Acceleration (PGA1 09875-01 Fault Dame Or Seismic Zone Distance from Site (m i) (km) Fault Type Maximum Magnitude Mmax (Mw) Avg Slip Rate (mm/yr) Avg Return Period (yrs) Fault Length (km) Mean Site PGA (g) Reference Notes: (1) (2) (3) 4 2 (2) (2 5 San Andreas - Southern 8.0 12.8 SS A 7.7 24 220 199 0.37 San Andreas - Mission Crk. Branch 8.3 13.3 SS A 7.2 25 220 95 0.30 San Andreas - Banning Branch 8.3 13.4 SS A 7.2 10 220 98 0.30 San Jacinto (Hot Spgs - Buck Ridge) 14.6 23.5 SS C 6.5 2 354 70 0.14 Blue Cut 16.4 26.5 SS C 6.8 1 760 30 0.15 San Jacinto-Anza 18.9 30.5 SS A 7.2 12 250 91 0.16 Burnt Mtn. 19.2 30.9 SS B 6.5 0.6 5000 21 0.11 San Jacinto -Coyote Creek 19.3 31.1 SS B 6.8 4 175 41 0.13 Eureka Peak 20.3 32.7 SS B 6.4 0.6 5000 19 0.10 Morongo 30.0 48.2 SS C 6.5 0.6 1170 23 0.07 Pinto Mountain 31.6 50.9 SS B 7.2 2.5 499 74 0.10 San Jacinto - Borrego 33.3 53.6 SS B 6.6 4 175 29 0.07 Emerson So. - Copper Mtn. 34.0 54.8 SS B 7.0 0.6 5000 54 0.08 Landers 34.4 55.4 SS B 7.3 0.6 5000 83 0.10 San Jacinto -San Jacinto Valley 35.7 57.4 SS B 6.9 12 83 43 0.08 Pisgah -Bullion Mtn. -Mesquite Lk 36.2 58.3 SS B 7.3 0.6 5000 89 0.09 Earthquake Valley 37.6 60.6 SS B 6.5 2 351 20 0.06 North Frontal Fault Zone (East) 40.1 64.6 RV B 6.7 0.5 1727 27 0.08 Brawley Seismic Zone 41.0 66.0 SS B 6.4 25 24 42 0.05 Elsinore -Julian 41.7 67.1 SS A 7.1 5 340 76 0.07 Johnson Valley (Northern) 45.2 72.7 SS B 6.7 0.6 5000 35 0.05 Elsinore -Temecula 45.8 73.7 SS B 6.8 5 240 43 0.06 Calico - Hidalgo 47.3 76.1 SS B 7.3 0.6 5000 95 0.07 Elmore Ranch 49.0 78.8 SS B 6.6 1 225 29 0.05 Elsinore -Coyote Mountain 49.1 79.0 SS B 6.8 4 625 39 0.05 Lenwood-Lockhart-Old Woman Sprgs 50.7 81.5 SS B 7.5 0.6 5000 145 0.08 North Frontal Fault Zone (West) 50.7 81.6 RV B 7.2 1 1314 50 0.08 Superstition Mtn. (San Jacinto) 51.9 83.5 SS B 6.6 5 500 24 0.04 Superstition Hills (San Jacinto) 52.9 85.1 SS B 6.6 4 250 23 0.04 Helendale - S. Lockhardt 58.1 93.4 SS B 7.3 0.6 5000 97 0.06 San Jacinto -San Bernardino 58.6 94.4 SS B 6.7 12 100 36 0.04 Elsinore -Glen Ivy 60.2 96.9 SS B 6.8 5 340 36 0.04 Weinert (Superstition Hills) 65.2 104.9 SS C 6.6 4 250 22 0.03 Cleghorn 66.6 107.2 SS B 6.5 3 216 25 0.03 Imperial 67.5 108.6 SS A 7.0 20 79 62 0.04 Brawley 68.8 110.8 SS A 7.0 20 79 62 0.04 Laguna Salada 69.9 112.5 SS B 7.0 3.5 336 67 0.04 Chino -Central Ave. (Elsinore) 73.5 118.3 RV B 6.7 1 882 28 0.04 Cucamonga 73.8 118.8 RV A 6.9 5 650 28 0.05 Notes: 1. Jennings (1994) and California Geologic Survey (CGS) (2003) 2. CGS (2003), SS = Strike -Slip, RV = Reverse, DS = Dip Slip (normal), BT = Blind Thrust 3. 2001 CBC, where Type A faults: Mmax > 7 & slip rate >5 mm/yr & Type C faults: Mmax <6.5 & slip rate < 2 mm/yr 4. CGS (2003) 5. The estimates of the mean Site PGA are based on the following attenuation relationships: Average of: (1) 1997 Boore, Joyner & Fumal; (2) 1997 Sadigh et al; (3) 1997 Campbell , (4) 1997 Abrahamson & Silva (mean plus sigma values are about 1.5 to 1.6 times higher) Based on Site Coordinates: 33.674 N Latitude, 116.301 W Longtude and Site Soil Type D EARTH SYSTEMS SOUTHWEST DESCRIPTIVE SOIL CLASSIFICATION Soil classification is based on ASTM Designations D 2487 and D 2488 (Unified Soil Classification System). Information on each boring log is a compilation of subsurface conditions obtained from the field as well as from laboratory testing of selected samples. The indicated boundaries between strata on the boring logs are approximate only and may be transitional. SOIL GRAIN SIZE U.S. STANDARD SIEVE 12" 3" 3/4" 4 10 40 200 GRAVEL I SAND BOULDERS COBBLES COARSE I FINE I COARSE I MEDIUM FINE SILT CLAY 305 76.2 19.1 4.76 2.00 0.42 0.074 0.002 SOIL GRAIN SIZE IN MILLIMETERS RELATIVE DENSITY OF GRANULAR SOILS (GRAVELS, SANDS, AND NON -PLASTIC SILTS) Very Loose "N=0-4 RD=0-30 Easily push a 1/2 -inch reinforcing rod by hand Loose N=5-10 RD=30-50 Push a 1/2 -inch reinforcing rod by hand Medium Dense N=11-30 RD=50-70 Easily drive a 1/2 -inch reinforcing rod with hammer Dense N=31-50 RD=70-90 Drive a 1/2 -inch reinforcing rod 1 foot with difficulty by a hammer Very Dense N>50 RD=90-100 Drive a 1/2 -inch reinforcing rod a few inches with hammer 'N=Blows per foot in the Standard Penetration Test at 60% theoretical energy. For the 3 -inch diameter Modified California sampler, 140 -pound weight, multiply the blow count by 0.63 (about 2/3) to estimate N. If automatic hammer is used, multiply a factor of 1.3 to 1.5 to estimate N. RD=Relative Density (%). C=Undrained shear strength (cohesion). CONSISTENCY OF COHESIVE SOILS (CLAY OR CLAYEY SOILS) Very Soft *N=0-1 'C=0-250 psf Squeezes between fingers Soft N=24 C=250-500 psf Easily molded by finger pressure Medium Stiff N=5-8 C=500-1000 psf Molded by strong finger pressure Stiff N=9-15 C=1000-2000 psf Dented by strong finger pressure Very Stiff N=16-30 C=2000-4000 psf Dented slightly by finger pressure Hard N>30 C>4000 Dented slightly by a pencil point or thumbnail MOISTURE DENSITY Moisture Condition: An observational term; dry, damp, moist, wet, saturated. Moisture Content: The weight of water in a sample divided by the weight of dry soil in the soil sample expressed as a percentage. Dry Density: The pounds of dry soil in a cubic foot. MOISTURE CONDITION RELATIVE PROPORTIONS Dry .....................Absence of moisture, dusty, dry to the touch Damp................Slight indication of moisture Moist.................Color change with short period of air exposure (granular soil) Below optimum moisture content (cohesive soil) Wet....................High degree of saturation by visual and touch (granular soil) Above optimum moisture content (cohesive soil) Saturated .......... Free surface water PLASTICITY DESCRIPTION FIELD TEST Nonplastic A 1/8 in. (3 -mm) thread cannot be rolled (2" outside diameter) at any moisture content. Low The thread can barely be rolled. Medium The thread is easy to roll and not much No Recovery time is required to reach the plastic limit. High The thread can be rerolled several times after reaching the plastic limit. GROUNDWATER LEVEL Water Level (measured or after drilling) Water Level (during drilling) Trace.............minor amount (<5%) with/some...... significant amount modifier/and... sufficient amount to influence material behavior (Typically >30%) LOG KEY SYMBOLS ' Bulk, Bag or Grab Sample Terms and Symbols used on Boring Logs 0 %, Earth Systems Southwest Standard Penetration Split Spoon Sampler (2" outside diameter) ' Modified California Sampler (3" outside diameter) �= No Recovery Terms and Symbols used on Boring Logs 0 %, Earth Systems Southwest GRAPHIC LETTERSYMBOL MAJOR DIVISIONS SYMBOL TYPICAL DESCRIPTIONS Well -graded gravels, gravel -sand GW mixtures, little or no fines CLEAN GRAVELS GRAVEL AND 'r .■ .+ .• .• .■ .+ .■GRAVELLY r GP- Poorly-graded gravels, gravel -sand .r.. +- .- .- .- .- ....-. mixtures. Little or no fines SOILS .r..;�..r..r..�..�,.�.. GM Silty gravels, gravel -sand -silt COARSE More than 50% of GRAVELS ............ mixtures GRAINED SOILS coarse fraction WITH FINES I retained on No. 4 Clayey gravels, gravel -sand -clay sieve GC mixtures SW Well -graded sands, gravelly sands, SAND AND CLEAN SAND little or no fines SANDY SOILS (Little or no fines) ::;' SP Poorly -graded sands, gravelly More than 50% of sands, little or no fines material is larger than No. 200 I.. sieve size :.: .:...:..:.':::::::::::: SM Silty sands, sand -silt mixtures SAND WITH FINES f ::::::::::::.`:`:`:.`::::: More than 50% of (appreciable coarse fraction passing ssing No. 4 sieve amount of fines) SC Clayey sands, sand -clay mixtures Inorganic silts and very fine sands, ML rock flour, silty low clayey fine sands or clayey silts with slight plasticity LIQUID LIMIT Inorganic clays of low to medium LESS THAN 50 CL plasticity, gravelly clays, sandy 'FINE-GRAINED SOILS clays, silty clays, lean clays OL Organic silts and organic silty ME 2 clays of low plasticity SILTS AND Inorganic silty, micaceous, or CLAYS MH diatomaceous fine sand or tore silty soils than 50% of material is smaller LIQUID LIMIT CH Inorganic clays of high plasticity, han No. 200 GREATER fat clays �ieve size THAN 50 ............. ............. Organic clays of medium to high ............. OH plasticity, organic silts .YJ'J'.YJ'YJ'.YYYYY YYYYYYYY'' Y' Peat, humus, swamp soils with HIGHLY ORGANIC SOILSyyyyyyyyyyy' PT high organic contents .rrr.r.rrrrrrrr VARIOUS SOILS AND MAN MADE MATERIALS Fill Materials MAN MADE MATERIALS Asphalt and concrete Soil Classification System Earth Systems aS Southwest Earth Systems WON, Southwest 79-811B Country Club Drive, Indio, CA 92203 Phone (760) 345-1588, Fax (760) 345-7315 Boris No: B-1 13,19,30 7,9,12 5,7,9 6,8,14 Drilling Date: October 7, 2004 Project Name: Lot 6 Desert Club 41, La Quinta CA SILTY SAND: pale yellowish brown, dense to very dense, dry, fine grained, poor recovery medium dense, lense of sand with silt moderate yellowish brown, very fine to fine grained Drilling Method: 8" Hollow Stem Auger File Number: 09875-01 ` Drill Type: CME 55 w/Rope & Cathead Boring Location: See Figure 2 Logged By: Dirk Wiggins v Sample Type,.; Penetration 7,9,15 Description of Units Page 1 of 1 u Resistance _ ° � Q CL - � ° Note: The stratification lines shown represent the y p E — c approximate boundary between soil and/or rock types Graphic Trend q h. 0 (Blows/6") rn q j and the transition may be gradational. Blow Count Dry Density -5 - 10 - 15 - 20 - 25 - 30 - 35 - 40 - 45 - 50 - 55 - 60 13,19,30 7,9,12 5,7,9 6,8,14 SM 93 1 SILTY SAND: pale yellowish brown, dense to very dense, dry, fine grained, poor recovery medium dense, lense of sand with silt moderate yellowish brown, very fine to fine grained ML SILT: dark yellowish brown, medium dense, dry, very fine to fine grained 7,9,15 Total Depth 21.5 feet No Groundwater Encountered ' �j Earth Systems 79-811 B Country Club Drive, Indio, CA 92203 ~� SouthwesttPhone (760) 345-1588, Fax (760) 345-7315 Boring No: B-2 3,4,5 5,7,9 7,11,12 9,15,25 SM Drilling Date: October 7, 2004 Project Name: Lot 6 Desert Club #1, La Quinta CA Drilling Method: 8" Hollow Stem Auger File Number: 09875-01 Drill Type: CME 55 w/Rope & Cathead Boring Location: See Figure 2 No Groundwater Encountered Logged By: Dirk Wiggins v Sample Type,., Penetration 3 Description of Units Page 1 of 1 y Resistance _ A a = ° Note: The stratification lines shown re p represent the A T e approximate boundary between soil and/or rock types Graphic Trend q m K. (Blows/6") O t j and the transition may be gradational. Blow Count Dry Density -5 - 10 - 15 - 20 - 25 - 30 - 35 - 40 - 45 - 50 - 55 -60 3,4,5 5,7,9 7,11,12 9,15,25 SM 96 1 83 2 SILTY SAND: moderate yellowish brown, loose, dry, fine grained medium dense, very fine to fine grained pale yellowish brown, lense of silt dense Total Depth 15.5 feet No Groundwater Encountered Earth Systems 79-811B Country Club Drive, Indio, CA 92203 Southwest Phone (760) 345-1588, Fax (760) 345-7315 Boring NO: B-3 6,8,9 4,5,6 5,6,7 10,15,20 10,15,24 Drilling Date: October 7, 2004 Project Name: Lot 6 Desert Club # 1, La Quinta CA Drilling Method: 8" Hollow Stem Auger File Number: 09875-01 Drill Type: CME 55 w/Rope & Cathead Boring Location: See Figure 2 fine grained Logged By: Dirk Wiggins Sample T e Type Penetration N � � Description of Units Page 1 of 1 t;; u n !._ v Resistance _ O E fn U �. p n .o r Note: The stratification lines shown represent the q Total Depth 21 feet q .. c approximate boundary between soil and/or rock types Graphic Trend q (Blows/6") yr Q U and the transition may be gradational. Blow Count Dry Density -5 - 10 - 15 - 20 - 25 - 30 - 35 - 40 - 45 - 50 - 55 - 60 6,8,9 4,5,6 5,6,7 10,15,20 10,15,24 SM ML 99 2 88 3 SILTY SAND: moderate yellowish brown; loose, dry, very fine to fine grained dense, fine grained SILT: pale yellowish brown, dense, dry, very fine to fine grained 32,50/5" 92 8 Total Depth 21 feet No Groundwater Encountered Earth Systems Southwest 79-811 B Country Club Drive, Indio, CA 92203 Phone (760) 345-1588, Fax (760) 345-7315 Boring No: B-4 Drilling Date: October 7, 2004 ProjectName: Lot 6 Desert Club # 1, La Quinta CA Drilling Method: 8" Hollow Stem Auger File Number: 09875-01 Drill Type: CME 55 w/Rope & Cathead Boring Location: See Figure 2 Logged By: Dirk Wiggins Sample Type Penetration 89 2 °-'' Description of Units Page I of 1 4 aResistance _ E U q n •o Note: The stratification lines shown represent the Y p �, q " approximate boundary between soil and/or rock types Graphic Trend q 0. 0 (Blows/6") V) Q � jc and the transition may be gradational. Blow Count Dry Density -5 -10 - 15 - 20 - 25 - 30 - 35 - 40 - 45 - 50 - 55 - 60 SM SILTY SAND: moderate yellowish brown, medium dense, dry, very fine to fine grained 8,10,17 89 2 12,19,28 Z 96 2 dense, fine grained 9,10,12 ML SILT: pale yellowish brown, medium dense, dry, fine grained, lense of silty sand Total Depth 14 feet No Groundwater Encountered APPENDIX B Laboratory Test Results 0 EARTH SYSTEMS SOUTHWEST N t File No.: 09875-01 December 8, 2004 UNIT DENSITIES AND MOISTURE CONTENT ASTM D2937 & D2216 Job Name: SWC Desert Club, Lot 6, La Quinta B 1 5 Unit Moisture USCS Sample Depth Dry Content Group Location (feet) Density (pcf) (%) Symbol B 1 5 93 1 SM B2 9 96 1 SM B2 14 83 2 SM/ML B3 10 99 2 SM B3 15 88 3 ML B3 20 92 8 ML B4 2.5 89. 2 SM B4 7.5 96 2 SM EARTH SYSTEMS SOUTHWEST File No.: 09875-01 Job Name: SWC Desert Club, Lot 6, La Quinta Lab Number: 04=0670 December 8, 2004 AMOUNT PASSING NO. 200 SIEVE ASTM D 1140 Fines USCS Sample Depth Content Group Location (feet) (%) _ Symbol B2 9 49 SM EARTH SYSTEMS SOUTHWEST File No.: 09875-01 December 8, 2004 PARTICLE SIZE ANALYSIS ASTM D-422 Job Name: SWC Desert Club, Lot 6, La Quinta Sample ID: BI @ 1-4 Feet Description: Brown, Sandy Silt, (SM) 100 90 80 70 on 60 S 50 a- 40 30 20 10 0 - 100 Sieve Percent Size Passing 1-1/2" 100 .111 100 3/411 100 1/2" 100 3/8" 100 #4 100 #8 98 #16 97 #30 96 #50 89 #100 68 #200 41 % Gravel: 0 % Sand: 59 % Silt: 30 % Clay (3 micron): 11 (Clay content by short hydrometer method) j j �� I � � i I Ilil, I i I I ! III !. I i I, I I� i I j; i� ll I � � I I i I I , L JiW M 10 1 Particle Size( mmq. I EARTH SYSTEMS SOUTHWEST 0.01 0.001 1 File No.: 09875-01 December 8, 2004 a CONSOLIDATION TEST ASTM D 2435 & D 5333 SWC Desert Club, Lot 6, La Quinta Initial Dry Density: 94.4 pcf ' 13-1 @ 5 feet Initial Moisture, %: 0.9% Silty F Sand (SM) Specific Gravity (assumed): 2.67 Ring Sample Initial Void Ratio: 0.766 Hydrocollapse: 1.3% @ 2.0 ksf % Change in Height vs Normal Presssure Diagram ' ---&—Before Saturation Hydrocollapse ■ After Saturation ' ' 0.1 1.0 10.0 Vertical Effective Stress, ksf EARTH SYSTEMS SOUTHWEST 2 ' � 1 0 -2 ' ao -3 x a 4 Z an ° -5 V L -7 a -8 -9 -10 ' -11 -12 ' 0.1 1.0 10.0 Vertical Effective Stress, ksf EARTH SYSTEMS SOUTHWEST V File No.: 09875-01 December 8, 2004 MAXIMUM DENSITY / OPTIMUM MOISTURE ASTM D 1557-91 (Modified) Job Name: SWC Desert Club, Lot 6, La Quinta Procedure Used: A Sample ID: Bl @ 1-4' Feet Preparation Method: Moist Location: Native Rammer Type: Mechanical Description: Brown, sandy silt w/Gravel (SM) Sieve Size % Retained Maximum Density: 118.5 pcf 3/411 0.0 Optimum Moisture: 11.5% 3/8" 1.7 #4 4.4 140 135 130 125 120 c. 15 110 105 00-, 0 5 10 15 20 25 30 Moisture Content, percent EARTH SYSTEMS SOUTHWEST 35 MMEMME MME 1 Emil MUM 0 ME MEN r LM ff =110MM EN 00-, 0 5 10 15 20 25 30 Moisture Content, percent EARTH SYSTEMS SOUTHWEST 35 File No.: 09875-01 Lab Number: 04-0670 SOIL CHEMICAL ANALYSES December 8, 2004 Job Name: SWC Desert Club, Lot 6, La Quinta Amount in Soil Job No.: 09875-01 Soluble Sample ID: BI Low Sample Depth, feet: 1-4' DF RL Sulfate, mg/Kg (ppm): 56 1 0.50 Chloride, mg/Kg (ppm): 30 1 0.20 pH, (pH Units): • 8.96 1 0.41 Resistivity, (ohm -cm): 3,311 N/A N/A Conductivity, (µmhos -cm): 302 1 2.00 Note: Tests performed by Subcontract Laboratory: Truesdail Laboratories, Inc. DF: Dilution Factor 14201 Franklin Avenue RL: Reporting Limit Tustin, California 92780 Tel: (714) 730-6239 General Guidelines for Soil Corrosivity Chemical Agent Amount in Soil Degree of Corrosivity Soluble 0 -1000 mg/Kg (ppm) [ 0-.1%] Low Sulfates 1000-2000 mg/Kg (ppm) [0.1-0.2%] Moderate 2000 - 20,000 mg/Kg (ppm) [0.2-2.0%] Severe > 20,000 m (ppm) [>2.0%] Very Severe Resistivity 1-1000 ohm -cm Very Severe 1000-2000 ohm -cm Severe 2000-10,000 ohm -cm Moderate 10,000+ ohm -cm Low EARTH SYSTEMS SOUTHWEST