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05-1475 (SFD) Geotechnical Engineering ReportJUL 15 2005 PALM DESERT MASTER BUILDERS, INC. 79-720 IRIS COURT LA QUINTA, CALIFORNIA 92253 GEOTECHNICAL ENGINEERING REPORT PROPOSED SINGLE-FAMILY RESIDENCE LOT 81D, THE HIDEAWAY LA QUINTA, CALIFORNIA December 6, 2004 r © 2004 Earth Systems Southwest Unauthorized use or copying of this document is strictly pr i without the express written consent of Earth Systems Sout <, File No.: 09889-01 ' 04-11-787 By. JUL 15 2005 It%S� Earth Systems 1/ Southwest 79-811 B Country Club Drive Indio, CA 92203 (760)345-1588 (800)924-7015 FAX (760) 345-7315 December 6, 2004 File No.: 09889-01 ,. Palm Desert Master Builders, Inc. 04-11-787 79-720 Iris Court La Quinta, California Attention: Mr. Kenny Dickerson Project: Proposed Single -Family Residence Lot 81 D, The Hideaway La Quinta, California Subject: Geotechnical Engineering Report Dear Mr. Dickerson: We take pleasure in presenting this geotechnical engineering report prepared for the proposed single-family residence to be located on Lot 81D within The Hideaway Country C=ub 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, da -ed October 8, 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 report or its recommendations Respectfully s g s/o EARTH S EST ' m CE 3823 w Craig S. EXP. 03/31/05 CE 38234 CML 4TF0F CA��EDP SER/csh/reh Distribution: 6/Palm Desert Master Builders, Inc. 1/RC File; 2/BD File lJ I 1 TABLE OF CONTENTS Page EXECUTIVE SUMMARY..................:........................................................................ii 1 EARTH SYSTEMS SOUTHWEST Section 1 INTRODUCTION...........................................................................................1 1.1 Project Description............................................................................................ l 1.2 1.3 Site Description.................................................................................................1 Purpose and Scope of Work..............................................................................2 Section 2 METHODS OF INVESTIGATION ................................................ _............. 3 2.1 Field Exploration................................................................................_.............3 2.2 Laboratory Testing.............................................................................................3 Section 3 3.1 DISCUSSION............................................................................................4 Soil Conditions . ... ... .4 3.2 Groundwater...................................................................................................... 4 3.3 3.4 Geologic Setting................................................................................................4 Geologic Hazards...............................................................................................5 Section 6 LIMITATIONS AND ADDITIONAL SERVICES....................................16 6.1 Uniformity of Conditions and Limitations......................................................16 3.4.1 Seismic Hazards....................................................................................5 6.2 Additional Services..........................................................................................17 3.4.2 Secondary Hazards................................................................................6 3.4.3 Site Acceleration and Seismic Coefficients...........................................7 Section4 CONCLUSIONS..............................................................................................9 1 EARTH SYSTEMS SOUTHWEST Section 5 RECOMMENDATIONS..............................................................................10 SITE DEVELOPMENT AND GRADING..................................................................10 5.1 Site Development — Grading............................................................................10 5.2 Excavations and Utility Trenches.................................................................... 11 5.3 Slope Stability of Graded Slopes..................................................................... l l STRUCTURES............................................................................................................11 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 1 EARTH SYSTEMS SOUTHWEST L J 1 ]] 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 Via Dona, within The Hideaway Country Club, in the City of La Quinta, California. The proposed development will consist of a custom single-family residence. We understand that the proposed structure 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 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. 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 strong 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. t Ci IEARTH SYSTEMS SOUTHWEST 1 [I 1 1 1 iii SUMMARY OF RECOMMENDATIONS Design Item Recommended Parameter Referebce-Sectron No Foundations Allowable Bearing Pressure Continuous wall footings 1,500 psf 5.4 Pad (Column) footings 2,000 psf Foundation Type 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 . Low to 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 Type SD 3.4.3; 5.7 Near -Source Distance 10.2 km 3.4.3; 5.7 Near Source Factor, NA 1.00 3.4.3; 5.7 Near Source Factor, Nv 1.19 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 z70 feet 3.2 Estimated Fill and Cut <2 feet — fill <2 feet — cut 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. IEARTH SYSTEMS SOUTHWEST 1 fl December 6, 2004 GEOTECHNICAL ENGINEERING REPORT PROPOSED SINGLE-FAMILY RESIDENCE LOT 81D, THE HIDEAWAY LA QUINTA, CALIFORNIA Section 1 INTRODUCTION 1.1 Project Description File No.: 09889-01 04-11-787 This geotechnical engineering report has been prepared for the proposed custom single-family home to be constructed on Lot 81D located on Via Dona, within The Hideaway Country Club, in the City of La Quinta, California. a The proposed custom home will likely be a two-story structure. We understand tha; the proposed structure will be of wood -frame and stucco construction and will be supported b} 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 sidewal{s 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 custom home is to be constructed on the vacant lot on the west side of Via Dona, within The Hideaway Country Club, in the City of La Quinta, California. The site location is ' shown on Figure 1 in Appendix A. The project site consists of an irregular-shaped lot that has been previously rough graded in conjunction with development of the tract. Construction of the tract was ongoing at the time of our investigation; roadway paving, including curb and gutter construction, is pending. The proposed home site is relatively flat and level with adjacent properties at an elevation of approximately 20 feet above mean sea level. The site is relatively void of a.�y significant vegetation, with the exception of a sparse grass cover resulting from a temporary irrigation system. The site is bound by the unpaved Via Dona to the east, a golf course _o the west, a vacant lot to the south, and a golf cart pathway to the north. The history of past use and development of the property was not investigated as part of our scope of services. Some previous development of the site is possible. The site has been mass graded during construction of the tract. Buried remnants, such as old foundations, slabs, or septic systems, that may have existed on the site were likely exposed and removed duri-ig the overall tract grading, but may still exist. IEARTH SYSTEMS SOUTHWEST December 6, 2004 2 File kilo.: 09889-01 1 04-11-787 There may be underground utilities near and within the proposed 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 two exploratory borings to cepths ranging from 15.5 to 31.5 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. ,h ➢ 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. • Structure foundation type and design. • Allowable foundation bearing capacity and expected total and differential settlements. • Concrete slabs -on -grade. ,i • Mitigation of the potential corrosivity of site soils to concrete and steel -einforcement. • 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. IEARTH SYSTEMS SOUTHWEST 1 1 December 6, 2004 3 File No.: 09889-01 04-11-787 Section 2 METHODS OF INVESTIGATION 2.1 Field Exploration Two exploratory borings were drilled to depths ranging from 15.5 to 31.5 feet below the existing ground surface to observe the soil profile and to obtain samples for laboratory testing. The borings were drilled on October 15, 2004 using 8 -inch outside diameter hollow -stem augers, powered by a CME 75 truck -mounted drilling rig. The boring locations are shown on the boring location map, Figure 2, in Appendix A. The locations shown are approximate, :stablished 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 wide 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 automatic ham -mer, 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 resultE 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 o: typical soils encountered. ➢ Particle Size Analysis to classify and evaluate soil composition. -he gradation characteristics of selected samples were made by hydrometer and Fieve 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 6, 2004 4 File No.: 09889-01 04-11-787 Section 3 DISCUSSION 3.1 Soil Conditions The field exploration indicates that site soils consist generally of medium dense. interbedded fine-grained sand and silty sand (Unified Soil Classification System symbols of SP -SM and SM) with occasional silt layers (ML). The 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 -I -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. The hydroconsolidation potential is commonly mitigated by recompaction of a zone beneath building pads. The site lies within a recognized blow sand hazard area. Fine particulate matter (PM,o) 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. Historic high groundwater is believed to lie about 50 feet below original ground surface (and approximately 70 feet below existing grade) based on water well levels published in the vicinity of the site. 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 Miocene to Holocene sedimentary deposits. 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 1 Hill fault, the Banning fault, and the Mission Creek fault that traverse along the northeast margin of the valley. Local Geolo: The project site is located in the southern portion of the Coachella Valley, near the eastern flanks of the Santa Rosa Mountains, at an elevation of approximately 20 feet above 1, EARTH SYSTEMS SOUTHWEST F', December 6, 2004 5 File No.: 09889-01 04-11-787 mean sea level. The project is located in an area that was once covered by the ancient Lake Cahuilla. The sediments in this area of the valley generally consist of fine-grained sands with interbedded clays and silts of aeolian (wind-blown), lacustrine (lake bed), and alluvial (water -laid) origin. 3.4 Geologic Hazards 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 Mmax 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 California, 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); however, no active faults are mapped in the immediate vicinity of the site. 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 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 (6.1Mw) 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) 1 earthquake occurred near Big Bear Lake. No significant structural damage from these earthquakes was reported in the Palm Springs area. IEARTH SYSTEMS SOUTHWEST December 6, 2004 6 File No.: 09889-01 1 04-11-787 • 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 betw--en 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 Southern Segment of the fault (USGS, 2002). This segment has the longest elapEed 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 fle 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 skock (usually ' earthquake shaking), causing the soil to become a fluid mass. In general, for :he effects of liquefaction to be manifested at the surface, groundwater levels must be within 50 feet of the 1 ground surface and the soils within the saturated zone must also be susceptible tc liquefaction. The potential for liquefaction to occur at this site is considered low to negligiblT because the depth of groundwater beneath the site exceeds 50 feet. No free groundwater was encountered in our exploratory borings. The project site lies within the Riverside County Liquefaction Susceptibility Zone, but has a low potential because of the depth to groundwater. Ground Subsidence: The potential for seismically induced ground subsidence is considered to be slight 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 seismi,-ally induced settlement. Slope Instability: The site is relatively flat. Therefore, potential hazards from slope instability, landslides, or debris flows are considered negligible. IEARTH SYSTEMS SOUTHWEST 1 1 t December 6, 2004 7 File No.: 09889-01 04-11-787 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 Manc Risk Equivalent Return Period (years) PGA (g t 10% exceedance in 50 years 475 0.53 Notes: 1. Based on a soft rock site, SB/C, and soil amplification factor of 1.0 for Soil Profile Type Sp. 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. EARTH SYSTEMS SOUTHWEST December 6, 2004 8 File No.: 09889-01 04-11-787 2001 CBC Seismic Coefficients for Chapter 16 Seismic Provisions EARTH SYSTEMS SOUTHWEST 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: 10.2 km = 6.4 miles (San Andreas fault) Near Source Factor, Na: 1.00 Table 16-S Near Source Factor, Nv: 1.19 Table 16-T Seismic Coefficient, Ca: 0.44 = 0.44Na Table 16-Q Seismic Coefficient, Cv: 0.76 = 0.64Nv Table 16-R Seismic Hazard Zones: The site does lies within a liquefaction hazard area or zoze established by the 2002 Riverside County General Plan; however, the site is not located within a recognized landslide, or fault rupture hazard area or zone. Riverside County has not been mapped by the California Seismic Hazard Mapping Act (Ca. PRC 2690 to 2699). EARTH SYSTEMS SOUTHWEST 1 1 t t t December 6, 2004 9 File No.: 09889-01 04-11-787 Section 4 CONCLUSIONS The following is a summary of our conclusions and professional opinions base] 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 10.2 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 recommencations 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 measu-res to reduce seasonal flooding and erosion should be incorporated into site grading plans. Dust control should also be implemented during construction. Site grading shou_d 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 soils within the building and structural areas will require moisture Zonditioning, 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. EARTH SYSTEMS SOUTHWEST t December 6 2004 10 File No.: 09889-01 j 0 Section 5 4-11-787 RECOMMENDATIONS SITE DEVELOPMENT AND GRADING ' 5.1 Site Development — Grading A representative of Earth Systems Southwest (ESSW) should observe site clearinb, 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 should be removed from the proposed building, structural, and pavement areas. The surface should be strirped 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: We recommend that the pad be rolled with heavy equipment within the building area. The applied compactive effort should extend at least 5 feet outside the footprint of the proposed building and should include other portions of the site to be improved, such as driveways, sidewalks, patios, etc. The bottoms of the foundation excavations should be tested and probed to verify that the bearing soils have at least 90% relative compaction. If soft areas are encountered, it will be necessary to compact the bearing soils as specifies. above. Auxiliary Structures Suberade 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 fleet 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 1 (ASTM D 1557) for a depth of I foot below finished subgrades. Compaction shculd 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. 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 cf 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 1 source, import soil will not be prequalified by ESSW. The imported fill should be placed in lifts IEARTH SYSTEMS SOUTHWEST 1 December 6, 2004 11 File No.: 09889-01 04-11-787 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 be less than 5 percent for the upper excavated or scarified site soils. This estimate is based on compactive effort -o achieve an average relative compaction of about 92% and may vary with contractor methods. 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 (2% 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 prcperty may be backfilled with native soils compacted to a minimum of 90% relative compactiz)n. 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 (hori zontEl: 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 inc:ination. 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). 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. EARTH SYSTEMS SOUTHWEST becember 6, 2004 12 File No.: 09889-01 04-11-787 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 giver in this report. 1 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. Conventional Spread Foundations: Allowable soil bearing pressures are gi-�.en below for ' foundations bearing on recompacted soils as described in Section 5.1. Allowable bearing pressures are net (weight of footing and soil surcharge may be neglected). ➢ 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 bearingpressure may be used when calculating resistance to wind P Y g 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 (as specified in the California Building Code) 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 '/2 inch, expressed in a post -constriction 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 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 I calculating resistance to wind or seismic loads. Lateral passive resistance is based on the assumption that backfill next to foundations is properly compacted. IEARTH SYSTEMS SOUTHWEST December 6, 2004 13 File No.: 09889-01 1 04-11-787 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. I 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 protection 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-yeinforcement 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 Ivery low expansion subgrade. Concrete slabs and flatwork should be a minimum of 4 inches thick (actual, not nominal). We suggest that the concrete slabs be reinforced 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 '/2 -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 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 1 EARTH SYSTEMS SOUTHWEST r December 6, 2004 14 File No.: 09889-01 04-11-787 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 (138 ppm) and a low chloride ion concentration (52 ppm). Sulfate ions cEn 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 to severe 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 he quality of construction water used during grading and subsequent landscape irrigation. Earth Systems does not practice corrosion engineering. We recommend tha 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 resign should comply with the 2001 edition of the California Building Code using the seismic coefficients given in the table below. I I EARTH SYSTEMS SOUTHWEST December 6, 2004 15 File No.: 09889-01 04-11-787 2001 CBC Seismic Coefficients for Chapter 16 Seismic Provisions Seismic Zone: I 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: 11 t C t t 4 0.4 SD A 10.2 km = 6.4 miles 1.00 1.19 0.44 = 0.44Na 0.76 = 0.64Nv Reference Figure 16-2 Table 16-I Table l6 -J Table l6 -U (San Andreas fault) Table 16-S Table 16-T Table 16-Q Table 16-R The CBC seismic coefficients are based on scientific knowledge, engineering _ udgment, 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 minimurr, 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 1 December 6 2004 16 Section 6 LIMITATIONS AND ADDITIONAL SERVICES 6.1 Uniformity of Conditions and Limitations File No.: 09889-01 04-11-787 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. Variation3 in soil or groundwater conditions could exist between and beyond the exploration points. T_ -ie 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 :n 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 geotechnica- 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 general review of final design andspecifications PP h' g gn in order that earthwork and foundation recommendations may be properly int--rpreted 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 no= include an ' environmental assessment or an investigation for the presence or absence of wetlancs, hazardous EARTH SYSTEMS SOUTHWEST C n 1 1 fl 1 1 u December 6, 2004 17 File No.: 09889-01 04-11-787 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. • 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. •1• Appendices as cited are attached and complete this report. EARTH SYSTEMS SOUTHWEST December 6, 2004 18 File _v - No.: 09889 O1 04-11-787 REFERENCES 1 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. American Society of Civil Engineers (ASCE), 2003, Minimum Design Loads for Buildings and 1 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 Hazard Maps, California Geologic Survey (CGS), June 2003. California Department of Water Resources, 1964, Coachella Valley Investigation, Bulletin No. 108, 146 pp. ' Earth Systems Consultants Southwest, Geotechnical Engineering Report, Country Club of the Desert, Phase 1, La Quinta, California, File No.: 07117-10, Document No.: 00-09-772, dated September 22, 2000. ' Envicom Corporation and the Countyof 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 p 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 AEsessment for the State of California: California Division of Mines and Geology Open -File Report 96-08. Reichard, E.G. and Mead, J.K., 1991, Evaluation of a Groundwater Flow and Transport Model odel of the Upper Coachella Valley, California, U.S.G.S. Open -File Report 91-4142. 1 Riverside County Planning Department, 2002, Geotechnical Element of the Riverside County General Plan — Hearing Draft. EARTH SYSTEMS SOUTHWEST 1 1 El n December 6, 2004 19 File No.: 09889-01 04-11-787 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. 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 Seismologizal 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. EARTH SYSTEMS SOUTHWEST 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 EARTH SYSTEMS SOUTHWEST 1 Ct i Na ` ___==�==t / ,/���� is r a N i`�. *s.;Lw';�i1 iie �1 !♦a Oat. O Gs a ♦•}•• CO srst M i ��/ """ Jara N} •J} i •Ja � "{t ! t'j +V♦ ♦ J. N, 1F F, to Y. t� 1 fMi L�, Yr` 40 �,. ri-as✓f ,,.Ne 11 J•; I �� '.,"-. �.." a 1' assata'Ha ♦a♦y y��Tifso.M a}iii }JI-- ✓ t®♦ }}.s�neY • •,Q 'I ,�+. ytaia►� rN _---____ ♦i , ♦ ,- ✓1 •* ` I• :.il • ,p a _. -._ ��•., aG, . � 'i10'a}t♦.♦♦ieJii ___ a N CI �i ---- �l aJI ater I •},� ! • •. .,11 /a •" t•` r : 1 ,9 � ♦ �.isa II '� •�... i j , a �h' to �/(1 i.r 1 •a ail ♦• N �P, , o* l . !'' .Zi __ — P t- Well +� sw^r t. air�l;til : a i to -i nl:} a tt i It :. it- /�� `r 1 ` •.a a O. � —� ( �.� ice•—�-./�� � N � a ;' Reference: www.terraserver-usa.com Scale: 1" = 2,000' IIIA mm 0 2,000' 4,000' Y �1•: f• r • 1 r-+ a a a y -' � . n t �n if p a II tl m 11 9. 11 S ` II tl Ir- N I n N 0 I, If C I x_J2 " ii_25 ii • w i i. u it; 16 11 I' 11 tl II h w 41I — Figure 1 Site Location Map Lot 81 D, The Hideaway La QLinta, California Earth Systems Southwest 12/06/04 1 File No.: 09889-01 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 116°15'12"W 569000 56910) 569200 569300 569400 0 Via Dona i . LO -} + M M � _ } I } f LO n n i � 1 � h M M G '� i C rte., Q CD i Q M �= � N M Fy ' M 569000 56910) 569200 569300 569400 116°15'12"W 50 100 200 300 400 500 Feet N Figure 2 LEGEND Boring Location Map Lot 81 D, The Hideaway O Boring Location La Quinta, California Project Area ��-, Earth Systems o Southwest 12/06/04 1 File No.: 09889-01 ILot 81D,.The Hideaway 09889-01 Table 1 Fault Parameters & Deterministic Fstimates of Mean Pealc (_rnnnrl erralar finn Mr -Al Fault Name or Seismic Zone Distance from Site (ml) (krn) Fault Type Maximum Magnitude Mmax (MW) Avg Slip Rate (mm/yr) Avg Return Period (yrs) Fault Length (- ) Mean Site PGA (g) Reference Notes: 1 2 3 4 2 2 t2 (5 San Andreas - Southern 6.4 10.2 SS A 7.7 24 220 11`99 0.42 San Andreas - Mission Crk. Branch 8.1 13.0 SS A 7.2 25 220 95 0.31 San Andreas - Banning Branch 8.1 13.0 SS A 7.2 10 220 98 0.31 San Jacinto (Hot Spgs - Buck Ridge) 15.9 25.5 SS C 6.5 2 354 `70 0.13 Blue Cut 16.7 26.9 SS C 6.8 1 760 30 0.14 San Jacinto-Anza 20.0 32.1 SS A 7.2 12 250 9] 0.15 Burnt Mtn. 20.5 32.9 SS B 6.5 0.6 5000 21 0.10 San Jacinto -Coyote Creek 20.9 33.7 SS B 6.8 4 175 41 0.12 Eureka Peak 21.3 34.2 SS B 6.4 0.6 5000 .9 0.09 Morongo 31.9 51.3 SS C 6.5 0.6 1170 23 0.07 San Jacinto - Borrego 32.4 52.2 SS B 6.6 4 175 ?9 0.07 Pinto Mountain 33.2 53.5 SS B 7.2 2.5 499 74 0.10 Emerson So. - Copper Mtn. 34.1 54.9 SS B 7.0 0.6 5000 `4 0.08 Pisgah -Bullion Mtn. -Mesquite Lk 35.5 57.1 SS B 7.3 0.6 5000 89 0.10 Landers 35.5 57.1 SS B 7.3 0.6 5000 83 0.10 San Jacinto -San Jacinto Valley 38.4 61.9 SS B 6.9 12 83 43 0.07 Earthquake Valley 38.5 61.9 SS B 6.5 2 351 20 0.06 Brawley Seismic Zone 38.5 61.9 SS B 6.4 25 24 42 0.05 North Frontal Fault Zone (East) 41.8 67.2 RV B 6.7 0.5 1727 27 0.07 Elsinore -Julian 43.0 69.1 SS A 7.1 5 340 7 6 0.07 Johnson Valley (Northern) 46.3 74.5 SS B 6.7 0.6 5000 35 0.05 Elmore Ranch 46.5 74.8 SS B 6.6 1 225 29 0.05 Calico - Hidalgo 47.7 76.8 SS B 7.3 0.6 5000 �5 0.07 Elsinore -Temecula 48.1 77.4 SS B 6.8 5 240 f3 0.05 Elsinore -Coyote Mountain 48.9 78.6 SS B 6.8 4 625 =9 0.05 Superstition Mtn. (San Jacinto) 50.3 81.0 SS B 6.6 5 500 2-4 0.05 Superstition Hills (San Jacinto) 51.1 82.3 SS B 6.6 4 250 23 0.04 Lenwood-Lockhart-Old Woman Sprgs 52.2 84.0 SS B 7.5 0.6 5000 145 0.08 North Frontal Fault Zone (West) 52.8 85.0 RV B 7.2 1 1314 5:0 0.08 Helendale - S. Lockhardt 60.0 96.6 SS B 7.3 0.6 5000 97 0.06 San Jacinto -San Bernardino 61.4 98.7 SS B 6.7 12 100 36 0.04 Elsinore -Glen Ivy 62.9 101.3 SS B 6.8 5 340 36 0.04 Weinert (Superstition Hills) 63.2 101.7 SS C 6.6 4 250 22 0.04 Imperial 65.4 105.2 SS A 7.0 20 79 62 0.04 Brawley 66.6 107.2 SS A 7.0 20 79 62 0.04 Laguna Salada 68.5 110.2 SS B 7.0 3.5 336 67 0.04 Cleghorn 69.1 111.2 SS B 6.5 3 216 25 0.03 Rose Canyon 76.2 122.6 SS B 7.2 1.5 781 70 0.04 Chino -Central Ave. (Elsinore) 76.3 122.8 RV B 6.7 1 882 28 0.04 1NUWb. 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 nm/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: 33.667 N Latitude, 116.254 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. 12" 3" BOULDERS COBBLES GRAVEL COARSE 305 76.2 19.1 SOIL GRAIN SIZE U.S. STANDARD SIEVE 4 10 40 200 SAND NE I COARSE I MEDIUM FINE SILT CLAY 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 hemmer 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 Modi-ied California sampler, 140 -pound weight, multiply the blow count by 0.63 (about 2/3) to estimate N. If automatic hammer is used, nultiply 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 thumbnag 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 Trace ............. minor mount (<5%) Damp................Slight indication of moisture with/some...... significant amount Moist.................Color change with short period of air exposure (granular soil) modifier/and... sufficient amount to Below optimum moisture content (cohesive soil) influence material behavior Wet....................High degree of saturation by visual and touch (granular soil) (Typically >30%) Above optimum moisture content (cohesive soil) Saturated .......... Free surface water LOG KEY SYMBOLS PLASTICITY ' Bulk, Bag o -Grab Sample DESCRIPTION FIELD TEST Nonplastic A 1/8 in. (3 -mm) thread cannot be rolled at any moisture content. Standard Penetration Split Spoon Sampler Low The thread can barely be rolled. (2" outside diameter) Medium The thread is easy to roll and not much time is required to reach the plastic limit. ' Modified California Sampler MMoutside diameter) High The thread can be rerolled several times after reaching the plastic limit. GROUNDWATER LEVEL a No Recover, Water Level (measured or after drilling) Terms and Symbols used on Boring Logs Water Level (during drilling) Earth Systems Southwest 0 GRAPHIC LETTER MAJOR DIVISIONS SYMBOL SYMBOL TYPICAL DESCRIPTIONS Well -graded gravels, gravel -sand ' GW mixture 3, little or no fines CLEAN','•'•'.'� GRAVELS : : ;: A. . . GRAVEL AND r.•r.•;r. r• r• r. r. r. .•..•..••.•..•..••..•.. r• *..+ GP Poorly -graded gravels, gravel -sand GRAVELLY r.•r.•r.•..r. ..r.. + .+•.+ .+ .+•.+% . mixtures. Little or no fines SOILS .r•.r..�..,�•.r..r..�..1•. GM Silty gavels, gravel -sand -silt COARSE More than 50% of GRAVELS mixtur--s GRAINED SOILS coarse fraction WITH FINES retained on No. 4 Clayey gravels, gravel -sand -clay sieve GC mixtures SW Well sands, gravelly sands, SAND AND CLEAN SAND little or n® 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 sieve size SM Silty sands, sand -silt mixtures SAND WITH FINES More than 50% of (appreciable coarse fraction amount of fines) passing No. 4 sieve Sc Clayey sands, sand -clay mixtures Inorganic silts and very fine sands, M I ML rock flour, silty low clayey fine sands or clayey s=Its with slight plasticity Inorganic clays of low to medium FINE-GRAINED LIQUID LIMIT LESS THAN 50 CL plasticity gravelly clays, sandy ' SOILS clays, sil=y clays, lean clays iiiiii 11161 OL Organic silts and organic silty 11 M: i ::2 clays cf low plasticity ' SILTS AND 1 1 1 1 1 1 11 Inorganic silty, micaceous, or CLAYS tore MH diatomaceous fine sand or Silty SCiIS than 50% of material is smaller LIQUID LIMIT CH Inorganic- clays of high plasticity, an No. 200 GREATER fat clays leve size THAN 50 ............. ............. ............. OH Organic plays of medium to high ............. plasticity organic silts yy.YJ'J'y.YJ'J'y.YJ' HIGHLY ORGANIC SOILS yYyyyyyyy' YY yyyyyyyyyyyy PT Peat, humus, swam soils with p high orcanic contents yyyyyyyyyyyy [VARIOUS SOILS AND MAN MADE MATERIALS Fill Materials MAN MADE MATERIALS Asphalt and concrete Soil Classification System Earth Systems '-- Southwest 01 1 1 1 1 1 1 1 1 I 1 1 1 1 1 1 1 1 1 Earth Systems Southwest 79-8116 Countr, Club Drive, Indio, CA 92203 Phone (760) 345 1588, Fax (760) 345-7315 Boring No: B-1 SILTY SAND: dark yellowish brown, dense, Moist, Drilling Date: October 15, 2004 Project Name: Lot 81 D, The Hideaway, La Quinta, CA Drilling Method: 8" Hollow Stem Auger File Number: 09889-01 Drill Type: CME 75 w/Auto Hammer Boring Location: See Figure 2 Logged By: Dirk Wiggins v Sample Type Penetration 106 16 Description of Units iFPage I of I aResistance 0CIO U q c B- •o r- Note: The stratification lines shown represent the A Y Q a o (Blows/6") >, � � v c j approximate boundary between soil and/or rock types Graphic Trend M pale yellowish brown, loose, fine to medium graired to t 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: dark yellowish brown, dense, Moist, fine grained, lenses of silty sand 10,13,22 106 16 6,8,9 medium dense 3,4,4 pale yellowish brown, loose, fine to medium graired 1,1/12" SM/ML SILT AND SAND: dark to moderate yellowish brown, very loose, moist, very fine grained, lenses of silt 2,2,3 ML 84 35 SILT: dark yellowish brown, loose, moist, very fine grained, lenses of silty clay, micaceous 2,3,5 SM SILTY SAND: dark yellowish brown, loose to medium dense, moist, very fine to fine grained r 2,4,5 fine grained, lenses of very fine silt Total Depth 31.5 feet No Groundwater Encountered Earth Systems Southwest 5 10 15 20 25 30 35 40 45 50 55 60 79-811B Country Club Drive, Indio, CA 92203 Phone (760) 345-1588, Fax (760) 345-7315 Boring No: B-2 SM Drilling Date: October 15, 2004 ProjectName: Lot 81 D, The Hideaway, La Quinta, CA Drilling Method: 8" Hollow Stem Auger File Number: 09889-01 6,8,14 Drill Type: CME 75 w/Auto Hammer Boring Location: See Figure 2 fine grained, micaceous Logged By: Dirk Wiggins Sample 6,7, I3 no recovery vType,.; T e Penetration 5,10,12 °' � Description of Units Page 1 of 1 98 35 Resistance p E rn U c A 0 3- •o Y Note: The stratification lines shown represent the A Y q CA (Blows/6") �, A �� o approximate boundary between soil and/or rock types Graphic Trend medium dense, damp, fine grained m A U 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: dark yellowish brown, dense, moist, 6,8,14 103 10 fine grained, micaceous 6,7, I3 no recovery 5,10,12 98 6 SP -SM SAND WITH SILT: pale to dark yellowish brown, medium dense, damp, fine grained 5,7,10 90 9 SM SILTY SAND: dark yellowish brown, medium dense, damp, fine grained, micaceous Total Depth 15.5 feet No Groundwater Encountered APPENDIX B Laboratory Test Results EARTH SYSTEMS SOUTHWEST File No.: 09889-01 December 6, 2004 UNIT DENSITIES AND MOISTURE CONTENT ASTM D2937 & D2216 Job Name: Lot 81D, The Hideaway, La Quinta, CA Sample Location Depth (feet) Unit Dry Density (pcf) Moisture Content (%) USCS Group Symbol B 1 B1 2.5 106 16 SM B 1 20 84 35 ML B2 1 103 10 SM B2 9 98 6 SP -SM B2 14 90 9 SM EARTH SYSTEMS SOUTHWEST File No.: 09889-01 Job Name: Lot 81D, The Hideaway, La Quinta, CA Lab Number: 04-0695 December 6, 2004 AMOUNT PASSING NO. 200 SIEVE ASTM D 1 140 B1 15 80 ML EARTH SYSTEMS SOUTHWEST Fines USCS Sample Depth Content Group Location (feet) (%) Symbol B1 15 80 ML EARTH SYSTEMS SOUTHWEST 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 "File Nu.: 09889-01 Decerzber 6, 2004 PARTICLE SIZE ANALYSIS jiiji j I ill ASTM D-422 I!I ii I i t � I � i !��_ i!iji I IiI ! i I i i i i i �Ijil i , I I Iii i Job Name: Lot 81 D, The Hideaway, La Quinta, CA j Sample ID: B2 @ 1-4 Feet Description: Silty Sand, F (SM) I I 1 Sieve Percent Size Passing 1-1/2" 100 1" 100 I I ! 3/4" 100 jilj i j I 1/2" 100 3/8" 100 #4 100 #8 100 #16 100 % Gravel: 0 #30 100 % Sand: 65 #50 96 % Silt: 27 #100 71 % Clay (3 micron): 8 #200 35 (Clay content by short hydrometer method) 100 90 80 70 60 CZ °' 50 C N ci 40 30 20 10 0 �i!jl! I i ii I i jiiji j I ill 1 1 i I I I I!I ii I i t � I � i !��_ i!iji I IiI ! i I i i i i i �Ijil i , I I Iii i j ! I ! I I 1 I I i I I I i I I ! I jilj i j I II i.�ii i � hill l i I iiI ! I ;!Iii i 100 10 1 0.1 Particle Size ( mm) EARTH SYSTEMS SOUTHWEST 0.01 0.001 1 1 1 1 1 1 1 1 File No.: 09889-01 December 6, 2004 CONSOLIDATION TEST ASTM D 2435 & D 5333 Lot 81 D, The Hideaway, La Quinta, CA Initial Dry Density: 84.5 pcf B 1 @ 20' Feet Initial Moisture, %: 34.7% Silty Clay, (ML) Specific Gravity (assumed): 2.7-5 Ring Sample Initial Void Ratio: 1.031 Hydrocollapse: 0.5% @ 2.0 ksf % Change in Height vs Normal Presssure Diagram Et Before Saturation w' Hydrocollapse After Saturation �I� Rebound Trend Poly. (After Saturation) Vertical Effective Stress, ksf EARTH SYSTEMS SOUTHWEST r-1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 " File No.: 09889-01 December 6, 2004 MAXIMUM DENSITY / OPTIMUM MOISTURE ASTM D 1557-9; (Modified) Job Name: Lot 81D, The Hideaway, La Quinta, CA Procedure Used: A Sample ID: B2 @ 1-4' Feet Preparation MetLod: Moist Location: B2 @ 1-4' Feet Rammer Type: Mechanical Description: Medium Brown, Silty Sand (SM) Lab Number: 04-0695 Sieve Size % Retained Maximum Density: 117 pcf 3/4" 0.0 Optimum Moisture: 10.5% 3/8" 0.0 #4 0.0 140 135 130 125 110 105 100 ' ------------ Tr i I ; <----- Zero Air Voids Lines, i sg =2.65, 2,70, 2,75 .i i 4T� Ili I ' i I I I j i I i i;III I l ! i I i 0 5 10 15 20 25 Moisture Content, percent EARTH SYSTEMS SOUTHWEST 30 35 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 File No.: 09889-01 Decem-:)er 6, 2004 Lab Number: 04-0695 Amount in Soil SOIL CHEMICAL ANALYSES Soluble 0 -1000 mg/Kg (ppm) [ 0-.1%] Low Job Name: Lot 81D, The Hideaway, La Quinta, CA 1000-2000 mg/Kg (ppm) [0.1-0.2%] Job No.: 09889-01 Sample ID: B2 Severe Sample Depth, feet: 1-4' DF RL Sulfate, mg/Kg (ppm): 138 1 0.50 Chloride, mg/Kg (ppm): 52 1 0.20 pH, (pH Units): 8.59 1 0.41 Resistivity, (ohm -cm): 2,415 N/A N/A Conductivity, (µmhos -cm): 414 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 Ccrrosivity 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