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TR 31681 Andalusia (55 Series; Plans 1-3) - Geotechnical Engineering ReportEarth Systems Southwest CITY O&Ls QINTABUILDINFETY DEPT. APPROVED FOR CONSTRUCTION DATES 6S BY Consulting Engineers and Geologists-- T D DESERT DEVELOPMENT P.O. BOX 1716 LA QUINTA, CALIFORNIA 92253 GEOTECHNICAL ENGINEERING REPORT CORAL MOUNTAIN SEC MADISON STREET & AVENUE 58 LA QUINTA, CALIFORNIA September 2, 2003 ` © 2003 Earth Systems Southwest Unauthorized use or copying of this document is strictly prohibited , without the express written consent of Earth Systems Southwest. File No.: 09305-01 03-09-700 Earth Systems Southwest September 2, 2003 T D Desert Development P.O. Box 1716 La Quinta, CA 92253 Attention: Mr. Nolan Sparks Project: Coral Mountain SEC Madison Street & Avenue 58 La Quinta, California Subject: GEOTECHNICAL ENGINEERING REPORT Dear Mr. Nolan Sparks: 79-811B Country Club Drive Bermuda Dunes, CA 92201 (760)345-1588 (800)924-7015 FAX (760) 345-7315 File No.: 09305-01 03-09-700 We take pleasure to present this Geotechnical Engineering Report prepared for the proposed Coral Mountain development to be located at the southeast corner of Madison and Avenue 58 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 over -excavated and recompacted to improve bearing capacity and reduce settlement. The site is subject to strong ground motion and resulting soil liquefaction from the San Andreas Fault. Near surface soils have a severe sulfate content affecting concrete and requiring special mixes. 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 July 21, 2003. 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 to distribute 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 submitted, EARTH SYSTEMS UTHWEST Shelton L. Stringer GE 2266 SER/sls/dac pFtOFEssip ON L. 'Tq 14 0 Z 5, EXp 630604 �9�F�lFCHNIGP�. '_ \FCALIFOF�\� Distribution: 6/T D Desert Development 1/RC File 2/131) File TABLE OF CONTENTS Section4 CONCLUSIONS..................................................................................................13 Section 5 RECOMMENDATIONS....................................................................................14 Page EXECUTIVESUMMARY................................................................................................ii DEVELOPMENT AND GRADING.......................................................................14 Section 1 INTRODUCTION.................................................................................................1 Site Development - Grading...................................................................................14 1.1 Project Description..................................................................................................1 Excavations and Utility Trenches...........................................:..............................15 1.2 Site Description.......................................................................................................1 Slope Stability of Graded Slopes...................................................................:.......15 1.3 Purpose and Scope of Work....................................................................................2 Section 2 METHODS OF INVESTIGATION.....................................................................3 2.1 Field Exploration.....................................................................................................3 2.2 Laboratory Testing...................................................................................................4 Section3 DISCUSSION..................................................................................:......................5 3.1 Sol] Conditions........................................................................................................ 5 3.2 Groundwater............................................................................................................ 5 3.3 Geologic Setting......................................................................................................5 3.4 Geologic Hazards..................................................:.........................................:........6 3.4.1 Seismic Hazards..........................................................................................6 3.4.2 Secondary Hazards......................................................................................7 3.4.3 Site Acceleration and Seismic Coefficients .................................................8 3.5 Liquefaction.............................................................................................................9 Section4 CONCLUSIONS..................................................................................................13 Section 5 RECOMMENDATIONS....................................................................................14 SITE DEVELOPMENT AND GRADING.......................................................................14 5.1 Site Development - Grading...................................................................................14 5.2 Excavations and Utility Trenches...........................................:..............................15 5.3 Slope Stability of Graded Slopes...................................................................:.......15 STRUCTURES................................................................................................................16 5.4 Foundations...........................................................................................................16 5.5 Slabs-on-Grade......................................................................................................17 5.6 Retaining Walls.....................................................................................................18 5.7 Mitigation of Soil Corrosivity on Concrete...........................................................19 5.8 Seismic Design Criteria.........................................................................................19 5.9 Pavements..............................................................................................................20 Section 6 LIMITATIONS AND ADDITIONAL SERVICES..........................................22 6.1 Uniformity of Conditions and Limitations............................................................22 6.2 Additional Services................................................................................................23 REFERENCES....................................................................................................:..........24 APPENDIX A Site Location Map Boring Location Map Table I Fault Parameters 2003 International Building Code (IBC) Seismic Parameters Logs of Borings APPENDIX B Laboratory Test Results EARTH SYSTEMS SOUTHWEST EXECUTIVE SUMMARY The site is located at the southeast corner of Madison Street and Avenue 58 in the City of La Quinta, California. The proposed development will consist of residential housing, commercial areas, stretches of golf course, facility maintenance units and a clubhouse. We anticipate that the proposed structure will be wood -frame 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, street and parking lot construction, and concrete driveway and sidewalks. Based of the non-uniform nature and the hydro -collapse 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 severe seismic shaking and resulting soil liquefaction 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. The site soils have a severe sulfate content that can affect concrete. Special concrete mixes can mitigate this corrosive effect on the concrete. - EARTH SYSTEMS SOUTHWEST LE a SUMMARY OF RECOMMENDATIONS Design Item . Recommended Parameter: ; ..Reference Section?No:" ' Foundations Allowable Bearing Pressure 5.4 Continuous wall footings 1,500 psf Pad (Column) footings 1,800 psf Foundation Tye Spread Footing 5.4 Bearing Materials Engineered fill Allowable Passive Pressure 250 psf per foot 5.6 Active Pressure 35 pcf 5.6 At -rest Pressure 50 pcf 5.6 Allowable Coefficient of Friction 0.35 5.6 Soil Expansion Potential Very low EI<20 3.1 Geologic Hazards & Seismic Liquefaction Potential High 3.5.2 Significant Fault and Magnitude San Andreas, M7.7 5.8 Fault Type A 5.8 Seismic Zone 4 5.8 Soil Profile Tye Sp 5.8 Near -Source Distance 12.1 km (7.5 miles) 5.8 Seismic Coefficient, NA 1.00 5.8 Seismic Coefficient, Nv 1.12 5.8 Pavement TI equal to 4.5 (Light Traffic) 2.5" AC / 4.0" AB 5.9 TI equal to 5.0 (Light Traffic) 3.0"'AC / 4.0" AB 5.9 Slabs Building Floor Slabs On engineered fill 5.5 Modulus of Sub rade Reaction 200 pci 5.5 Existing Site Conditions Existing Fill N/A Soil Corrosivity Severe sulfates content 5.7 Groundwater Depth Presently >30 feet, Historic about 20 feet 3.2 Estimated Fill and Cut includes overexcavation 4 feet - fill 4 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. EARTH SYSTEMS SOUTHWEST September 2, 2003 1 of 25 File No.: 09305-01 03-09-700 GEOTECHNICAL ENGINEERING REPORT CORAL MOUNTAIN SEC MADISON STREET & AVENUE 58 LA QUINTA, CALIFORNIA Section 1 INTRODUCTION 1.1 Project Description This Geotechnical Engineering Report has been prepared for the proposed Coral Mountain development to be located at the southeast corner of Madison Street and Avenue 58 in the City of La Quinta, California. The proposed residential development will be a set of one-story structures with golf courses across the site. The proposed development will also consist of a commercial center proposed at the northwest corner of the site, two maintenance areas in the northeast and southwest areas, and a clubhouse facility located approximately at the center of the site. We anticipate that the proposed structures will be of wood -frame construction and will be supported by conventional shallow continuous or pad footings. Site development will include site grading, building pad preparation, underground utility installation, street and parking lot construction, and concrete driveway and sidewalk placement. Based on existing site topography and ground conditions, site grading is expected to consist of fills not exceeding 4 feet and cuts of about 4 feet (including over -excavation). We used maximum column loads of 25 kips and a maximum wall loading of 2.0 kips ,per linear foot as a basis for the foundation recommendations. All loading is assumed to be dead plus actual live load. We assumed the preliminary design loading. If actual structural loading exceeds these assumed values, we would need to reevaluate the given recommendations. ;. 1.2 Site Description The proposed site is located at the southeast corner of Madison Street and Avenue 58 in the City of La Quinta, California. The site location is shown on Figure l in Appendix A. The project site presently is relatively flat and consists of partially barren land. Some sections of the site are presently covered with vegetation primarily consisting of agricultural vegetation like date palm trees. 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, other than agricultural use, was observed on the site during our reconnaissance. Due to the agricultural use, pre-existing agricultural tile drains may be present. There may be underground utilities near and within the building area. These utility lines include but are not limited to domestic water, electric, sewer, telephone, cable, and irrigation lines. EARTH SYSTEMS SOUTHWEST ` September 2, 2003 2 of 25 File No.: 09305-01 03-09-700 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 13 exploratory borings to depths ranging from 16.5 to 31.5 feet, supplemented with 5 CPT sounding to a depth of about 50 feet. ➢ Laboratory testing of selected soil samples obtained from the exploratory borings. ➢ Review of selected published technical literature pertaining to the site and its surroundings, and previous geotechnical reports prepared for T D Desert Development (May 19, 2000 by Earth Systems Southwest) and Taylor -Woodrow Homes California Ltd. (May 18,1990 by Buena Engineers, Inc.). ➢ 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, including soil liquefaction and its mitigation. ➢ 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, • Lateral earth pressures and coefficients, • Mitigation of the potential corrosivity of site soils to concrete and steel reinforcement, • Seismic design parameters, • Preliminary pavement structural sections. 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. ➢ 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 's September 2, 2003 3 of 25 File No.: 09305-01 03-09-700 Section 2 METHODS OF INVESTIGATION 2.1 Field Exploration Thirteen exploratory borings were drilled to depths ranging from 16.5 to 31.5 feet below the existing ground surface to observe the soil profile and to obtain samples for laboratory testing. In addition, five electric cone penetrometer (CPT) soundings were advanced to approximate depths of 50 feet. The borings were made on July 31, 2003 using 8 -inch outside diameter hollow -stem augers, and powered by a Mobile CME 45 truck -mounted drilling rig. The boring and CPT locations are shown on the boring 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, however, may be gradational. CPT soundings provide a nearly continuous profile of the soil stratigraphy with readings every 5 cm (2 inch) in depth. Direct sampling for visual and physical confirmation of soil properties is generally recommended with CPT exploration in large geographical regions. Earth .Systems Southwest has generally confirmed the accuracy of CPT interpretations from extensive work at numerous Coachella Valley sites. The CPT exploration was conducted by hydraulically advancing an instrument Hogentogler 10 cm2 conical probe into the ground at a ground rate of 2 cm per second using a 23 -ton truck as a reaction mass. An electronic data acquisition system recorded a nearly continuous log of the resistance of the soil against the cone tip (Qc) and soil friction against the cone sleeve (Fs) as the probe was advanced. Empirical relationships (Robertson and Campanella, 1989) were applied to the data to give a nearly continuous profile of the soil stratigraphy. Interpretation of CPT data provides correlations for SPT blow count, phi (0) angle (soil friction angle), ultimate shear strength (Su) of clays, and soil type. Interpretive logs of the CPT soundings are presented in Appendix A of this report. EARTH SYSTEMS SOUTHWEST September 2, 2003 4 of 25 File No.: 09305-01 03-09-700 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 (ASTM D 2937). ➢ Maximum density tests were performed to evaluate the moisture -density relationship of typical soils encountered (ASTM D 1557). ➢ Particle Size Analysis (ASTM D 422) to classify and evaluate soil composition. The gradation characteristics of selected samples were made by hydrometer and sieve analysis procedures. ➢ Consolidation (Collapse Potential) (ASTM D 2435 and D5333) to evaluate the compressibility and hydroconsolidation (collapse) potential of the soil. ➢ R -Value test (ASTM D 2844) to evaluate the soil subgrade support for pavement design. ➢ Chemical Analyses (Soluble Sulfates & Chlorides, pH, and Electrical Resistivity) to evaluate the potential adverse effects of the soil on concrete and steel. EARTH SYSTEMS SOUTHWEST September 2, 2003 5 of 25 File No.: 09305-01 03-09-700 Section 3 DISCUSSION 3.1 Soil Conditions The field exploration indicates that site soils consist of primarily medium dense to dense silts, sands, silty sands and sandy silts, and low to medium plasticity clays. Silts and silty sands, with traces of clay, are predominant in the upper 10 to 15 feet. Layers of clayey soils are typically encountered at depths below 12 feet. . . 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. Consolidation tests indicate up to 1.7% collapse upon inundation, and is considered a slight site risk. 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 hardscape normally mitigates this hazard. 3.2 Groundwater Free groundwater was not encountered in the borings during exploration. Therefore, the depth to groundwater in the area can be assumed to be greater than 30 feet. Groundwater was measured at about 36 feet in previous CPT soundings made by Earth Systems Consultants Southwest in April 2000. Historical data indicated the groundwater depth was about 20 feet based on 1978 water well data obtained from the Coachella Valley Water District (USGS OFR 91-4142). However, there is uncertainty in the accuracy of short-term water level measurements. Groundwater levels may fluctuate with precipitation, irrigation, drainage, regional pumping from wells, and site grading. The absence of groundwater levels detected may not represent an accurate or permanent condition. 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 from San Gorgonio Pass, approximately 180.miles 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 EARTH SYSTEMS SOUTHWEST September 2; 2003 6 of 25 File No.: 09305-01 03-09-700 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. Local GeoloQy: The project site is located approximately 60 feet below mean sea level in the lower part of the Coachella Valley. The sediments within the valley consist of fine to coarse- grained sands with interbedded clays, silts, gravels, and cobbles 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 I in Appendix A.. The primary seismic hazard to the site is strong groundshaking 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). 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 over 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.l 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 & Big Bear Earthquakes - Early on June 28, 1992, a magnitude 7.5 Ms (7.3Mw) earthquake occurred near Landers, the largest seismic event in SouthernCalifornia for 40 years. Surface rupture EARTH SYSTEMS SOUTHWEST :, September 2, 2003 7 of 25 File No.: 09305-01 03-09-700 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. • Hector Mine Earthquake - On October 16, 1999, a magnitude 7.1Mw earthquake occurred on the Lavic Lake and Bullion Mountain Faults north of 29 Palms. This event while 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 to 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 elapsed time since rupture than any other 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 both 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 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 discussed further in Section 3.5 of this report. Ground Subsidence: The potential for seismically induced ground subsidence is considered to be high 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. Based on Tokimatsu and Seed methodology, we estimate that about 1.5 inches of total ground subsidence may occur in the upper 50 feet of soils for the Design Basis Earthquake ground motion. , EARTH SYSTEMS SOUTHWEST September 2, 2003 8 of 25 File No.: 09305-01 03-09-700 Slope Instability: The site is relatively flat. Therefore, potential hazards from slope instability, landslides, or debris flows are considered negligible. 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 also are 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. Because of these factors, an effective peak acceleration (EPA) is used in structural design. The following table provides the probabilistic estimate of the PGA and EPA taken from the 2002 CGS/ JSGS seismic hazard maps. EARTH SYSTEMS SOUTHWEST September 2, 2003 9 of 25 Estimate of PGA and EPA from 2002 CGS/11JSGS Prnhahilictir SPkMiC N517ard Manc File No.: 09305-01 03-09-700 Risk J Equivalent Return Period (years) I PGA (g) Approximate EPA (g) Z 10% exceedance in 50 years 1 475 1 0.50 0.45 Notes: 1. Based on a soft rock site, SB,c and soil amplification factor of 1.0 for Soil Profile Type SD. 2. Spectral acceleration (SA) at period of 0.2 seconds divided by 2.5 for 5% damping, as defined by the International Building Code. 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 and EPA estimates given above are 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 5.8 of this report. 2001 CBC Seismic Coefficients for Chapter 16 Seismic Provisions Seismic Hazard Zones: The site lies within a liquefaction hazard area established by the City of La Quinta General Plan. Riverside, County has not been mapped by the California Seismic Hazard Mapping Act (Ca. PRC 2690 to 2699). 2003 IBC Seismic Coefficients: For comparative purposes, the 2003 International Building Code (IBC) seismic and site coefficients are given in Appendix A. As of the issuance of this report, we are unaware when governing jurisdictions may adopt or modify the IBC provisions. 3.5 Liquefaction Soil liquefaction is a natural phenomenon that occurs when granular soils below the water table are subjected to vibratory motions, such as produced by earthquakes. Vibrations cause the water pressure to increase within soil pores, as the soil tends to reduce in volume. When the pore water pressure reaches the vertical effective stress, the soil particles become suspended in water causing a complete loss in soil strength. The liquefied soil behaves as a thick liquid. Liquefaction can cause excessive structural settlement, ground rupture, lateral .spreading EARTH SYSTEMS SOUTHWEST ' Reference Seismic Zone: 4 Figure 16-2 Seismic Zone Factor, Z: 0.4 Table 16-I Soil Profile Type: SD Table. 164 Seismic Source Type: A Table 16-U Closest Distance to Known Seismic Source: 12.1 km = 7.5 miles (San Andreas Fault) Near Source Factor, Na: 1.00 Table 16-S Near Source Factor, Nv: 1.12 Table 16-T Seismic Coefficient, Ca: 0.44 = 0.44Na Table 16-Q Seismic Coefficient, Cv: 0.71 = 0.64Nv Table 16-R Seismic Hazard Zones: The site lies within a liquefaction hazard area established by the City of La Quinta General Plan. Riverside, County has not been mapped by the California Seismic Hazard Mapping Act (Ca. PRC 2690 to 2699). 2003 IBC Seismic Coefficients: For comparative purposes, the 2003 International Building Code (IBC) seismic and site coefficients are given in Appendix A. As of the issuance of this report, we are unaware when governing jurisdictions may adopt or modify the IBC provisions. 3.5 Liquefaction Soil liquefaction is a natural phenomenon that occurs when granular soils below the water table are subjected to vibratory motions, such as produced by earthquakes. Vibrations cause the water pressure to increase within soil pores, as the soil tends to reduce in volume. When the pore water pressure reaches the vertical effective stress, the soil particles become suspended in water causing a complete loss in soil strength. The liquefied soil behaves as a thick liquid. Liquefaction can cause excessive structural settlement, ground rupture, lateral .spreading EARTH SYSTEMS SOUTHWEST ' September 2, 2003 10 of 25 File No.: 09305-01 03-09-700 (movement), or failure of shallow bearing foundations. Liquefaction is typically limited to the upper 50 feet of the subsurface soils. Four conditions are generally required before liquefaction can occur: 1. The soils must be saturated below a relatively shallow groundwater level. 2. The soils must be loosely deposited (low to medium relative density). 3. The soils must be relatively cohesionless (not clayey). Clean, poorly graded sands are the most susceptible. Silt (fines) content increase the liquefaction resistance in that more cycles of ground motions are required to fully develop pore pressures. If the clay content (percent finer than 2 micron size) is greater than 10%, the soil is usually considered non - liquefiable, unless it is extremely sensitive. 4. Groundshaking must be of sufficient intensity to act as a trigger mechanism. Two important factors that affect the potential for soil liquefaction are duration as indicated by earthquake magnitude (M) and intensity as indicated by peak ground acceleration (PGA). The soils encountered at the points of exploration included saturated sands and silty sands. The potential for liquefaction at this site is considered high Method of Analysis We have conducted a liquefaction analysis of the subsurface soils at the project site using the Robertson and Wride method as presented in 1997 NCEER Liquefaction Workshop proceedings. This method is an empirical approach to quantify the liquefaction hazard using CPT data from the site exploration and magnitude and PGA estimates from the seismic hazard analysis. The resistance to liquefaction is plotted on a chart of cyclic shear stress ratio versus a normalized tip resistance, Qc1N. Induced ground subsidence from soil liquefaction has been estimated using the 1987 Tokimatsu and Seed method by a computer spreadsheet, CPT- Liquefy.xls (Stringer, 2001). The Qc1N readings were adjusted to an equivalent clean sand blow count, N1(6o}cs according to the estimated fines content of the soil. The results of the analysis is that 5.6 to 12.5 feet of the substrata starting at about 20 -foot depth is likely to liquefy during the UBC Design Basis Earthquake (7.7M -0.5g) for 10% risk in 50 years. The results are summarized in the table below. The potentially liquefiable layers may be more or less extensive -than revealed by our investigation. EARTH SYSTEMS SOUTHWEST A. Sepiember 2, 2003 11 of 25 SUMMARY OF LIQUEFACTION ANALYSES Design Basis Earthquake (7.7Magnitude, 0.5g PGA) Historic Groundwater at 20 feet File No.: 09305-01 03-09-700 CPT Safety Factor Against Liquefaction Thickness of the Liquefied Zone (feet) Depth To First Liquefied Zone (feet) Estimated Induced Subsidence (inches) 1 0.4 5.6 33 0.6 2 0.5 5.9 20 0.8 3 0.5 12.5 21 1.5 4 0.4 10 20 1.4 5 0.6 8.2 23 0.7 Our analyses further indicate the site has probably never experienced liquefaction from earthquakes (Magnitudes 5.9 to 7.3) occurring in the last 100 years in vicinity of the project site. The likely triggering mechanism for liquefaction appears to be strong ground shaking (0.2g or greater) associated with the future rupture of the San Andreas Fault. Liquefaction Effects: We have estimated ground subsidence induced from liquefaction to be 1.5 inches. Differential building settlements may be estimated to be about 50 to 67% of the total subsidence, about 1/4 to 1 inches (SCEC, 1999). Based on empirical charts developed by Ishihaua (1985) and Youd and Garris (1995), surface ground disruption, cracking or sand boil formation may occur. The depth of the liquefiable layer would generally result in a wide areal ground subsidence rather than bearing capacity failure by the proposed structures. There is a low potential for lateral spreading (movement) of the ground because of the nearly level ground. Miti ation: Ground improvement methods to prevent liquefaction from occurring include vibroflotation compaction, stone columns, or compaction grouting. These methods are feasible but quite costly (on the order of $10 to $20/sf of treated area). More cost effective means to mitigate liquefaction damage (but do not prevent its occurrence) include deep foundation systems (piling), foundations 'that are structurally designed to withstand some differential movement or tilting, or a compacted zone of reinforced soil beneath the structure. Because of the high potential of differential settlement from soil liquefaction, new structures should be either founded on: • Foundations that use; grade beam footings to tie floor slabs and isolate columns to continuous footings, desigried-to"accoriimodate'the estimated differential settlement of 1 -inch in a 30 -foot span (1:360 angular distortion ratio). EARTH SYSTEMS SOUTHWEST Sepfember 2, 2003 12 of 25 File No.: 09305-01 03-09-700 • Structural mats that are flat -plate or waffled and use either conventionally reinforced or post - tensioned tendons, designed to accommodate the estimated differential settlement of 1 -inch in a 30 -foot span (1:360 angular distortion ratio). These alternatives reduce the effects of liquefaction by making the structures more able to withstand differential settlement and lateral movement. The minimum goal of liquefaction mitigation should be to provide a foundation system that can withstand the expected movement without causing such structural damage so as to pose a life -safety hazard (such as structural collapse from excessive drift). The choice of mitigation design alternatives depends on the economic costs of installation versus the economic risks that the owner and designer are willing to accept. EARTH SYSTEMS SOUTHWEST September 2, 2003 13 of 25 File No.: 09305-01 03-09-700 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 Mitieation: ➢' The primary geologic hazard is severe ground shaking and resulting soil liquefaction 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 and about 12.1 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 to the project site. 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, seismically induced flooding, and landslides are considered low on this site. ➢ The upper soils were found to be medium dense to very dense and are suitable 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 September 2, 2003 t Section 5 RECOMMENDATIONS 14 of 25 File No.: 09305-01 03-09-700 SITE DEVELOPMENT AND GRADING 5.1 Site Development - Grading A representative of Earth Systems Southwest (ESSW) should observe site clearing, grading, and the bottom 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, trees, large roots, pavements, foundations, 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 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 4 feet below existing grade or a minimum of 3 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. Moisture penetration to near optimum moisture should extend at least 5 feet below existing grade and be verified by testing. 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 only to extend 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 (silty sand or sandy silt) 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 September 2, 2003 15 of 25 File No.: 09305-01 03-09-700 Imported fill soils (if needed) should be non -expansive, granular soils meeting the USCS classifications of SM, SP -SM, or SW -SM with a maximum rock size of 3 inches and 5 to 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 25 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, equal to the depth of the excavation. Utility Trenches: Backfill of utilities within road 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). EARTH SYSTEMS SOUTHWEST September 2, 2003 16 of 25 File No.: 09305-01 03-09-700 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, but with a potential for seismic induced or hydroconsolidation settlement below the depth of recompaction. 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. Conventional Spread Foundations: Allowable soil bearing pressures are given 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: C 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 3000 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 3000 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 four, No. 4 steel reinforcing bars, two placed near the top and two 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 -construction angular distortion ratio of 1:480 or less. Seismic induced settlement may be as great at 1-'/z inches with 1 -inch differential in a 30 -foot span (1:360 angular distortion ratio). Foundations should be designed to accommodate this potential movement. EARTH SYSTEMS SOUTHWEST September 2, 2003 17 of 25 File No.: 09305-01 03-09-700 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 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 aide in concrete curing. The sand should be lightly moistened just prior to placing the concrete. Low -slump concrete should be used to help reduce the potential for concrete shrinkage. The effectiveness of the membrane is dependent upon its quality, method of overlapping, its protection during construction, and the successful sealing around utility lines. 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. 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 swell forces and 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 ('/ of slab depth) within 8 hours of concrete placement. Construction (cold) joints should consist of thickened butt joints with one- half 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 EARTH SYSTEMS SOUTHWEST September 2, 2003 18 of 25 File No.: 09305-01 03-09-700 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 arid desert region using proper batching, placement, and curing methods. Curing is highly effected 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 4500 -psi concrete, many of these quality control procedures are not required. 5.6 Retaining Walls The following table presents lateral earth pressures for use in retaining wall design. The values are given as equivalent fluid pressures without surcharge loads or hydrostatic pressure. Lateral Pressures and Sliding Resistance t Granular Backfill Passive Pressure 350 pcf -level ground Active Pressure (cantilever walls) 35 pcf - level ground Use when wall is permitted to rotate 0.1% of wall height At -Rest Pressure (restrained walls) 50 pcf - level ground Dynamic Lateral Earth Pressure Z Acting at 0.5H, 25H psf or 50 pcf Where H is height of backfill in feet Base Lateral Sliding Resistance Dead load x Coefficient of Friction: 0.50 Notes: I . These values are ultimate values. A factor of safety of 1.5 should be used in stability analysis except for dynamic earth pressure where a factor of safety of 1.2 is acceptable. 2. Dynamic pressures are based on the Mononobe-Okabe 1929 method, additive to active earth pressure.. Walls retaining less than 6 feet of soil and not supporting inhabitable structures need not consider this increased pressure (reference: CBC Section 1630A.1.1.5). Upward sloping backfill or surcharge loads from nearby footings can create larger lateral pressures. Should any walls be considered for retaining sloped backfill or placed next to foundations, our office should be contacted for recommended design parameters. ' Surcharge loads should be considered if they exist within a zone between the face of the wall and a plane projected 45 degrees upward from the base of the wall. The increase in lateral earth pressure should be taken as 35% of the surcharge load within this zone. Retaining walls subjected to traffic loads should include a uniform surcharge load equivalent to at least 2 feet of native soil. Drainage: A backdrain or an equivalent system of backfill drainage should be incorporated into the retaining wall design. Our firm can provide construction details when the specific application is determined. Backfill immediately behind the retaining structure should be a free -draining granular material. - Waterproofing should be according to the designer's specifications. Water should not be allowed to pond near the top of the wall. To accomplish this, the final backfill grade should be such that all water is diverted away from the retaining wall. EARTH SYSTEMS SOUTHWEST September 2, 2003 19 of 25 File No.: 09305-01 03-09-700 Backfill and Subgrade Compaction: Compaction on the retained side of the wall within a horizontal distance equal to one wall height should be performed by hand -operated or other lightweight compaction equipment. This is intended to reduce potential locked -in lateral pressures caused by compaction with heavy grading equipment. Foundation subgrade preparation should be as specified in Section 5.1. 5.7. 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 an severe sulfate ion concentration (>15,000 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 requires for very severe sulfate conditions that Type V Portland Cement plus pozzolan be used with a maximum water cement ratio of 0.45 using a minimum 4,500 psi concrete mix (CBC Table 19-A-4). The pozzolan used should have service record of improved sulfate resistance when used in concrete containing Type V cement. 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 severe to very 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, w or encapsulating with densely consolidated concrete. 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. 5.8 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 September 2, 2003 20 of 25 File No.: 09305-01 03-09-700 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 SF** A 12.1 km = 7.5 miles 1.00 1.12 0.44 = 0.44Na 0.71 = 0.64Nv Reference Figure 16-2 Table 16-I Table 16-J Table 16-U (San Andreas Fault) Table 16-S Table 16-T Table 16-Q Table 16-R *** Note Soil Profile Type, SF as defined by CBC Section 1629.3.1 includes soils that are vulnerable to potential failure from seismic loading such as liquefaction. The site lies within a Riverside County designated soil liquefaction hazard zone. For purposes of Regular CBC designed structures, the seismic coefficients given are for. the pre -liquefied soil seismic response, similar to Soil Profile type Sp. 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 all 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. 5.9 Pavements Since no traffic loading was provided by the design engineer or owner, we have assumed traffic loading for comparative evaluation. The design engineer or owner should decide the appropriate traffic conditions for the pavements. Maintenance of proper drainage is advised to prolong the service life of the pavements. Water should not pond on or near paved areas. The' following table provides our preliminary recommendations for pavement sections. Final pavement sections recommendations should be based on design traffic indices and R -value tests conducted during grading after actual subgrade soils are exposed. EARTH SYSTEMS SOUTHWEST September 2, 2003 21 of 25 File No.: 09305-01 03-09-700 PRELIMINARY RECOMMENDED PAVEMENTS SECTIONS R -Value Sub2rade Soils - 40 (assumed) Desien Method — CALTRANS 1995 Notes: 1. Asphaltic concrete should be Caltrans, Type B, 1/2 -in. or 3/4-1n. maximum -medium grading and compacted to a minimum of 95% of the 75 -blow Marshall density (ASTM D 1559) or equivalent. 2. Aggregate base should be Caltrans Class 2 (3/4 in. maximum) and compacted to a minimum of 95% of ASTM D 15 57 maximum dry density near its optimum moisture. 3. All pavements should be placed on 12 inches of moisture -conditioned subgrade, compacted to a minimum of 90% of ASTM D 1557 maximum dry density near its optimum moisture. 4. Portland cement concrete should have a minimum of 3250 psi compressive strength @ 28 days. 5. Equivalent Standard Specifications for Public Works Construction (Greenbook) may be used instead of Caltrans specifications for asphaltic concrete and aggregate base. Flexible Pavements Rigid Pavements Asphaltic Aggregate Portland Aggregate Traffic Concrete Base Cement Base Index Pavement Use Thickness Thickness Concrete Thickness (Assumed) (Inches) (Inches) (Inches) (Inches) 4.5 Auto Parking Areas 2.5 4.0 4.0 4.0 5.0 Residential Streets 3.0 4.0 5.0 4.0 Notes: 1. Asphaltic concrete should be Caltrans, Type B, 1/2 -in. or 3/4-1n. maximum -medium grading and compacted to a minimum of 95% of the 75 -blow Marshall density (ASTM D 1559) or equivalent. 2. Aggregate base should be Caltrans Class 2 (3/4 in. maximum) and compacted to a minimum of 95% of ASTM D 15 57 maximum dry density near its optimum moisture. 3. All pavements should be placed on 12 inches of moisture -conditioned subgrade, compacted to a minimum of 90% of ASTM D 1557 maximum dry density near its optimum moisture. 4. Portland cement concrete should have a minimum of 3250 psi compressive strength @ 28 days. 5. Equivalent Standard Specifications for Public Works Construction (Greenbook) may be used instead of Caltrans specifications for asphaltic concrete and aggregate base. September 2, 2003 22 of 25 File No.: 09305-01 03-09-700 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 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 investigation for the presence or absence of wetlands, hazardous or EARTH SYSTEMS SOUTHWEST September 2, 2003 23 of 25 File No.: 09305-01 03-09-700 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. • 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. -000- Appendices as cited are attached and complete this report. EARTH SYSTEMS SOUTHWEST September 2, 2003 24 of 25 File No.: 09305-01 03-09-700 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 l through 5. 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. 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. International Code Council (ICC), 2003, International Building Code, 2003 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. Reichard, E.G. and Mead, J.K., 1991, Evaluation of a Groundwater Flow and Transport Model of the Upper Coachella Valley, California, U.S.G.S. Open -File Report 91-4142. 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. EARTH SYSTEMS SOUTHWEST September 2, 2003 25 of 25 File No.: 09305-01 03-09-700 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. I � � ' P 't ` it it " - 1� � '. - U ° V .. ': �'• . • • . _ -12 ': i n-25 �. 'h �.; ._ AVENUF_ 56'. I......— --r, -- IL— AVENUE 566 I �--- •• �r:-471r •` `�.yl, .. � t -6 ...... �-1►1 �.y, II ly tt sr AVEj/UE 'i i II 58 ° I .AVE NUE I - • ''� �• • — — - y -- u 28 w'\\f `\ li�=-� I-',l � � I ♦ !1 Wit. Oev4D•D I U� .. f:- _. ��--•. Q_ e , i - aFrsao'si pica j. �l atler at•calulQ ae t '1 Cy Par i i� , I s �•.^� :. a w�owaw ltreaq -6 I ;.1 \ .y II . $; :'�".�'ft •., � s r Rap atQse`�•i .., :�� G I /``: '}. •Sw'Zi i.�.... �V \� fOc@bR3�1;46at r O it etaboaq epsoa , AO_U_FQUC7 °. i. Ik' - r ....:...^_ �`Vtrm4natrp+�+Re i •�c+ �1 _PlPE11_i.E..-- 11 �\�I` N O I II .r aj+-.'-.....7. oa.ea9eftev Dept e0ame F 2 I q. �„ G', ZG I. .^..FCS '•'.X�kl`�.�_ A�/Qaa. seme9 sa'peGsaku.vwa w� I . ��v � L6 �-.�.1-_. � sae cveq bp,atosa�oD'aav - % I, a --�' sAfloi+mE pen 7Ta faaE!o9'ey Sr; S: I➢, V1 i U� l ,..-rW,L`: `....''.. a o' m ots'oa amc ars.♦C I' �. i°; ` 1 a 1 �" mgr. •�• ab iaeoe •.eoaQ •obmtm op ; T 7 ��`1 n 2.+ / ,�. �'"� '�',c„^r,�--,•a Raaaawos.Rna veo e•e �'han I p �"&';.5 II ;f' :I_� I /I "� aaey a'aw oe + ¢ • ae c s'� �1•� V �'•' aaame+ R ed •4 of OeOti+ ee I v' %f •1, �f \ r� I � ui�'� 9 r .t � •+uesppo ds Gor epee ass 1 .. ...`. .. ...... � (,. �:.\�i.'1^.�'.v .11•I.\ \\c` _� s�\`_=-moi: ___. ` - ,o' ,. t,«�:: «:`s`'d 1 .�•t".I aa9�e6R Ogee. a'a aripa vis as f j��;,^• 52 ,%• ` - 7 -,,, �. ( ---- L •' Ir7`- !� �ro a0-Dr G05004D0 aaR a4\e '�' 4 bwGa'O• 6 P. O ab aba � , ?� � � -� � •�OitIS C19'OT ba aEeO+bOrw fuH 1 ,�a'oo ae coaep ea Dow avotc 1 1 i 1 a �� l I .• -,� vvy naa -� •"e ea rb seP wiG T<•N:6. II`�. �. �I_� �'vo oa zl5„h(wr."�i•-epmb GC O�STwN p+6RT aO.e QdO ��; - I e retoR+a� ,,,,,�,,,,�.... _a ___meoese vcge. w,ar 4,76 ry,..A:Vt/VUE ti0•' ..-�. \ 4 II \ t Swi4Ltr>l3PB Ptia[l I , ro Z' , , ,. I `e ♦ < AVE s. 33 35 - I • �. `•l \`I 'i \°.' :;P:.t 1 i f F is .. ) Reference: USGS Topographic Map, abc Quadrangle, La Quinta 1982 (photorevised) Scale: 1” = 2,000' I 0 2,000 4,000 Figure 1 - Site Location Coral Mountain S.E.C. Madison Street & Avenue 58, La Quinta , Riverside County, California File No.: 09305-01 Earth Systems �i Southwest , Avenue 58 CPT -2 . . . . . . . . . . PT I -ED 2 B-1 3 'a B 5 OCPT-3 B-1 0 z ...... IN CO z TI B-3 B VNI B-8 -5 CPT 13CPT4 :4 (D. A; Avenue bu LEGEND Figure 2 - Boring & CPT Locations B -I Approximate Boring Locations Coral Mountain And Numbers S. E.C. Madison Street &Avenue 58, La Quinta, jk CPT_5 Riverside County, California (D Approximate CPT Locations File No.: 09305-01 And Numbers Earth Systems P = 700' Southwest GO Coral Mountain Table 1 Fault Parameters & R, notarminictir Ti ctimotoc of Moan Ponlr Crnunrl Arrrlrrntinn (PCAI 09305-01 Fault Name or Seismic Zone Distance from Site (mi) (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 7.5 12.1 SS A 7.7 24 220 199 0.39 San Andreas.- Mission Crk. Branch 10.8 17.4 SS A 7.2 25 220 95 0.25 San Andreas - Banning Branch 10.8 17.4 SS A 7.2 10 220 98 0.25 San Jacinto-Anza 18.2 29.3 SS A 7.2 12 250 91 0.16 San Jacinto -Coyote Creek 19.8 31.8 SS B 6.8 4 175 41 0.12 Burnt Mtn. 23.4 37.7 SS B 6.5 0.6 5000 21 0.09 Eureka Peak 24.2 38.9 SS B 6.4 0.6 5000 19. 0.08 San Jacinto - Borrego 29.6 47.6 SS B 6.6 4 175 29 0.07 Pinto Mountain 35.9 57.8 SS B 7.2 2.5 499 74 0.08 Brawley Seismic Zone 36.0 57.9 SS B 6.4 25 24 42 0.05 Emerson So. - Copper Mtn. 36.7 59.0 SS B 7.0 0.6 5000 54 0.07 Earthquake. Valley 36.7 59.1 SS B 6.5 2 351 20 0.05 Pisgah -Bullion Mtn. -Mesquite Lk 37.6 60.4 SS B 7.3 0.6 5000 89 0.08 Landers 38.4 61.9 SS B 7.3 0.6 5000 83 0.08 San Jacinto -San Jacinto Valley 40.0 64.4 SS B 6.9 12 83 43 0.06 Elsinore -Julian 41.5 66.8 SS A 7.1 5 340 76 0.07 Elmore Ranch 43.8 70.5 SS B 6.6 1 225 29 0.05 North Frontal Fault Zone (East) 44.7 72.0 DS B 6.7 0.5 1727 27 0.06 Elsinore -Coyote Mountain 46.3 74.6 SS B 6.8 4 625 39 0.05 Superstition Mtn. (San Jacinto) 47.4 76.2 SS B 6.6 5 500 24 0.04 Elsinore -Temecula 48.1 77.4 SS B 6.8 5 240 43 0.05 Superstition Hills (San Jacinto) 48.2 77.5 SS B 6.6 4 250. 23 0.04 Johnson Valley (Northern) 49.2 79.2 SS B 6.7 0.6 5000 35 0.04 Calico - Hidalgo 50.5 81.2 SS B 7.3 0.6 5000 95 0.06 `Lenwood-Lockhart-Old Woman Sprgs 55.2 88.8 SS B 7.5 0.6 5000 145 0.06 North Frontal Fault Zone (West) 55.7 89.6 DS B 7.2 1 1314 50 0.06 Weinert (Superstition Hills) 60.3 97.0 SS C 6.6 4 250 22 0.03 Notes: 1. Jennings (1994) and California Geologic Survey (CGS) (2003) 2. CGS. (2003), SS = Strike -Slip, DS = Dip Slip, 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 y (mean plus sigma values are about 1.5 to 1.6 times higher) Based on Site Coordinates: 33.628 N Latitude, 116.233 W Longtude and Site Soil Type D EARTH SYSTEMS SOUTHWEST Coral Mountain 0.2 0.0 2000 IBC Equivalent Elastic Static Response Spectrum 09305-01 Period Sa T (sec) (g Table 2 0.00 0.40 2000, 2003 International 0.05 0.65 Building Code (IBC) Seismic Parameters Seismic Category D Table 1613.3(1) Site Class D Table 1615.1.1 Latitude: 0.60 1.00 33.628 N Longitude: -116.233 W 0.80 0.75 Maximum Considered Earthquake (MCE) Ground Motion 0.90 0.67 Short Period Spectral Reponse Ss 1.50 g Figurel615(3) 1 second Spectral Response St 0.60 g Flgurel6l5(4) Site Coefficient Fa 1.00 Table 1615.1.2(1) Site Coefficient FV 1.50 Table 1615.1.2(2) SMs 1.50 g = Fa*Ss 1.60 0.38 SMI 0.90 g = F„*Sl Design Earthquake Ground Motion 1.80 0.33 Short Period Spectral Reponse SDs 1.00 g = 2/3*SMs I second Spectral Response SDI 0.60 g = 2/3*SM, To 0.12 sec = 0.2*SDI/SDs Ts 0.60 sec = So,/SDs 0.2 0.0 2000 IBC Equivalent Elastic Static Response Spectrum 09305-01 0.0 0.5 1.0 1.5 2.0 1.90 0.32 Period (sec) 2.00 0.30 2.20 0.27 EARTH SYSTEMS SOUTHWEST Period Sa T (sec) (g 0.00 0.40 0.05 0.65 .0.12, 1.00 0.20 1.00 0.30 1.00 0.60 1.00 0.70 0.86 0.80 0.75 0.90 0.67 1.00 0.60 1.10 0.55 1.20 0.50 1.30 0.46 1.40 0.43 1.50 0.40 1.60 0.38 1.70 0.35 1.80 0.33 0.0 0.5 1.0 1.5 2.0 1.90 0.32 Period (sec) 2.00 0.30 2.20 0.27 EARTH SYSTEMS SOUTHWEST Earth Systems Southwest 5 10 15 20 25 30 35 40 79-811 B Country Club Drive, Bermuda Dunes, CA 92201 Phone (760) 345-1588 FAX (760) 345-7315 Boring No: B-1 ML SILT: grayish olive, medium dense, dry, very fine Drilling Date: July 31, 2003 Project Name: Coral Mountain, La Quinta, CA Drilling Method: 8" Hollow Stem Auger File Number: 09305-01 75 2 grained, trace small marine shells, trace very thin small roots Drill Type: CME 45 with cathead Boring Location: See Figure 2 Logged By: Karl Hewes v Sample Type. Penetration light olive, very dense, trace clay, non plastic, trace small voids C Description of Units Page I of I U' Resistance _ E � Q a _ NThe lineshresent the Note: e stratification sown represent Y p T v e approximate boundary between soil and/or rock types Graphic Trend p m N 0 (Blows/6") V)Q 12,15,21 U and the transition may be gradational. Blow Count Dry Density 5 10 15 20 25 30 35 40 ML SILT: grayish olive, medium dense, dry, very fine 8,8,9 75 2 grained, trace small marine shells, trace very thin small roots 11,21,33 89 5 light olive, very dense, trace clay, non plastic, trace small voids 21,24,26 94 5 very dense, trace clay, non plastic, small marine shells become more frequent 9,16,28 97 9 very dense i 12,15,21 SP -SM SAND WITH SILT: light olive gray, dense, dry, medium grained with some coarse and fine grained 4,6,7 CL CLAY: dusky yellow clay with silt, medium dense, moist, medium plasticity, trace very small voids 10,7,8 SM SILTY SAND: grayish olive, medium dense, damp, fine grained, trace marine shells, some thin silt interbedded layers to 1/2" thick SM/ML SANDY SILT: grayish olive, medium dense, damp, very fine grained, silty, trace silt interbedded layers 9,9,9 to 1/4" thick, trace marine shells Total Depth 31.5 feet No groundwater encountered Southwest Earth Systems 79-811 B Country Club Drive, Bermuda Dunes, CA 92201 Phone (760) 345-1588 FAX (760) 345-7315 Boring No: B-2 Drilling Date: July 31, 2003 Project Name: Coral Mountain, La Quinta, CA Drilling Method: 8" Hollow Stem Auger File Number: 09305-01 Drill Type: CME 45 with cathead Boring Location: See Figure 2 Logged By: Karl Hewes Sample v Type Penetration _ Description of Units Page 1 of 1 the s Resistance Q Q Note: The stratification lines shown represent 0� U y p T �� o approximate boundary between soil and/or rock types Graphic Trend p m in (Blows/6") Q V and the transition may be gradational. Blow Count Dry Density 5 10 15 20 - 25 - 30 - 35 - 40 12,17,23 SM 93 I SILTY SAND: grayish olive, very dense, dry, very fine grained, trace thin roots, trace small marine 18,31,43 SQL 99 1 shells, trace very small voids SANDY SILT: grayish olive, very dense, dry, silt, SP -SM 9,21,33 102 t very fine grained, trace small marine shells SAND WITH SILT: dense, dry, fine to very fine 10,28,36 grained light grayish olive, no marine shells 10,9,9 5 10 15 20 - 25 - 30 - 35 - 40 12,17,23 SM 93 I SILTY SAND: grayish olive, very dense, dry, very fine grained, trace thin roots, trace small marine 18,31,43 SQL 99 1 shells, trace very small voids SANDY SILT: grayish olive, very dense, dry, silt, SP -SM 9,21,33 102 t very fine grained, trace small marine shells SAND WITH SILT: dense, dry, fine to very fine 10,28,36 grained light grayish olive, no marine shells 10,9,9 CL CLAY: moderate olive brown dense dry, silt, low to medium plasticity SM SILTY SAND: grayish olive, dense, damp, very fine to fine grained 7,9,9 slightly more moisture Total Depth 18.5 feet r , No groundwater encountered Earth Systems %'Zft7w7 Southwest 79-811 B Country Club Drive, Bermuda Dunes, CA 92201 Phone (760) 345-1588 FAX (760) 345-7315 Boring No: B-3 Drilling Date: July 31, 2003 Project Name: Coral Mountain, La Quinta, CA Drilling Method: 8" Hollow Stem. Auger File Number: 09305-01 13,16,19 Drill Type: CME 45 with cathead Boring Location: See Figure 2 Logged By: Karl Hewes -74 Sample Type Penetration 88 0 trace small marine shells a Description of Units Page 1 of 1 Resistance 14,21,22 U p U •`— d Note: The stratification lines shown represent the ,a, Y 0 2 o approximate boundary between soil and/or rock types Graphic Trend p � o � (Blows/6") p U and the transition may be gradational. Blow Count Dry Density M cn same as above -5 - 10 - 15 - 20 - 25 - 30 - 35 - 4Q SM SILTY SAND: grayish olive, medium dense, dry; 13,16,19 fine grained, trace roots to 4" long 1/8" diameter, 88 0 trace small marine shells 14,21,22 dense 101. 0 10,12,17 same as above 96 1 7,18,28 dense ML SILT: grayish olive, dry, sandy silty, very fine . grained . 7,13,20 CL CLAY: light olive, very stiff, damp, low to medium plasticity, trace small marine shells, some thin clay laminations at 16 feet 10,17,21 SM SILTY SAND: light grayish olive, medium dense, damp, fine grained Total Depth 21.5 feet No groundwater encountered 0%EarthSystems t� Southwest 79-8118 Country Club Drive, Bermuda Dunes, CA 92201 Phone (760) 345-1588 FAX (760) 345-7315 Boring No: B-4 Drilling Date: July 31, 2003 Project Name: Coral Mountain, La Quinta, CA Drilling Method: 8" Hollow Stem Auger File Number: 09305-01 Drill Type: CME 45 with cathead Boring Location: See Figure 2 Logged By: Karl Hewes Sample Type '� � ,�. Description of Units Page 1 of I F ,Penetration U' Resistance � U °' u .N Q Q Note: The stratification lines shown represent the Y o T o approximate boundary between soil and/or rock types Graphic Trend p m (Blows/6") Ca U and the transition may be gradational. Blow Count Dry Density 6,21,31 ML 105 1 SILT: grayish olive, very dense, dry, very fine to fine grained, trace small marine shells 10,14,14 dense 94 3 SP -SM SAND WITH SILT: moderate olive brown, medium 6,15,25 dense, dry, fine grained 5 105 1 light olive gray 12,22,35 96 2 ML SILT: grayish olive, dense, dry, very fine grained, trace small marine shells 10 7,12,21 97 16 CL CLAY: light olive, hard, damp, trace small voids, decomposed small piece of wood, low to medium plasticity, becomes more silty at 13 feet 15 8,14,13 SM SILTY SAND: light olive gray, medium dense, dry, fine grained 20 Total Depth 18.5 feet No groundwater encountered 25 30 35 nn Earth Systems Southwest 79-8116 Country Club Drive, Bermuda Dunes, CA 92201 Phone (760) 345-1588 FAX (760) 345-7315 Boring No: B-5 Drilling Date: July 31, 2003 Project Name: Coral Mountain, La Quinta, CA SILTY SAND: grayish olive, medium dense, dry, Drilling Method:. 8" Hollow Stem Auger File Number: 09305-01 9,14,18 Drill Type: CME 45 with cathead Boring Location: See Figure 2 fine grained, trace small marine shells, trace roots Logged By: Karl Hewes Sample Type Penetration 98 2 o '.'�. Description of Units Page 1 of 1 o v Resistance _ 7,11,13 0 cL `— � Note: The stratification lines shown represent the Y o T (J3„ �vo SILT: grayish olive, dense, dry, very fine grained, clay becomes more prominent at 6 feet approximate boundary between soil and/or rock types Graphic Trend p CO (Blows/6") C] U and the transition may be gradational. Blow Count Dry Density 5 10 15 20 25 30 — 35 40 0 SM SILTY SAND: grayish olive, medium dense, dry, 9,14,18 98 0 fine grained, trace small marine shells, trace roots 5,13,15 98 2 same as above 7,11,13 93 12 ML SILT: grayish olive, dense, dry, very fine grained, clay becomes more prominent at 6 feet } 4,5,8 light olive, medium dense, non plastic, trace thin clay interlayers 4,5,7 CL CLAY: light olive, stiff, damp, trace small marine shells, low plasticity 6,6,8 SM SILTY SAND: grayish olive, medium dense, dry, fine grained, some orange staining Total Depth 21.5 feet No groundwater encountered , 2 ,Y 0 Earth Systems ~� Southwest79-811B 8'12'16 Country Club Drive, Bermuda Dunes, CA 92201 Phone (760) 345-1588 FAX (760) 345-7315 Boring No: B-6 98 6 SILT: grayish olive, dense, damp, very fine grained, , trace small marine shells, trace roots Drilling Date: July 31, 2003 Project Name: Coral Mountain, La Quinta; CA 7,11,14 Drilling Method: 8" Hollow Stem Auger 86 File Number: 09305-01 Drill Type: CME 45 with cathead Boring Location: See Figure 2 Logged By: Karl Hewes v Sample yp Penetration Type.. 5,5,8 Description of Units Page 1 of 1 ML aResistance 29 o p n 3 y •o Note.' The stratification lines shown represent the „ in v c approximate boundary between soil and/or rock types Graphic Trend p (Blows/6") O U and the transition may be gradational. Blow Count Dry Density 5 10 fk i- 15 t— 20 25 30 35 40 8'12'16 ML 98 6 SILT: grayish olive, dense, damp, very fine grained, , trace small marine shells, trace roots 7,11,14 ML/CL 86 16 CLAYEY SILT: light olive, very stiff, damp, medium plasticity, high frequency of roots to 3/8" 5,5,8 ML 83 29 diameter, trace small voids SILT: moderate olive brown, medium dense, damp, 5,8,16 very fine grained CL CLAY: light olive, very stiff, moist, low plasticity, trace roots to 1/4" diameter, laminated clay layers 15,15,15 SM SILTY SAND: light olive gray, medium dense, moist, fine grained 6,9,15 SM/ML SANDY SILT: light olive, medium dense, damp very fine grained, some silt laminations Total Depth 18.5 feet No groundwater encountered 1�) Earth Systems Boring No: B-% Drilling Date: August 1, 2003 Project Name: Coral Mountain, La Quinta, CA SILT: moderate olive brown, medium dense, moist, Drilling Method: 8" Hollow Stem Auger File Number: 09305-01 4,5,7 Drill Type: CME 45 with cathead Boring Location: See Figure 2 24 very fine grained, trace roots to 1/8", trace clay Logged By: Karl Hewes v Sample yp Penetration Type 4,7,11 94 Description of Units Page 1 of 1 n Resistance _ E En � c O a Y y o N Note: The stratification lines shown represent the p ML y Q 14 q .. c approximate boundary between soil and/or rock types Graphic Trend M m (Blows/6") 4,6,5 q U and the transition may be gradational. Blow Count Dry Density 5 10 15 - 20 - 25 - 30 - 35 - 40 ML SILT: moderate olive brown, medium dense, moist, 4,5,7 83 24 very fine grained, trace roots to 1/8", trace clay 4,7,11 94 20 grayish olive, dense, damp, trace roots to 1/4" diameter 7,9,13 ML 98 14 SANDY SILT: grayish olive, dense, damp, very fine to fine grained, trace roots 4,6,5 85 36 CL SILTY CLAY: moderate olive brown, stiff, wet, very fine grained, some laminated silt layers, trace roots 5,7,8 SM SILTY SAND: grayish olive, medium dense, moist, fine to medium grained with trace coarse grained 5,8,9 SM/ML SANDY SILT: grayish olive, medium dense, moist, very fine grained Total Depth 21.5 feet No groundwater encountered Earth Systems IWIS Southwest 79-811 B Country Club Drive, Bermuda Dunes, CA 92201 Phone (760) 345-1588 FAX (760) 345-7315 Boring No: B-8 Drilling Date: August 1, 2003 Project Name: Coral Mountain, La Quinta; CA Drilling Method: 8" Hollow Stem Auger File Number: 09305-01 Drill Type: CME 45 with cathead Boring Location: See Figure 2 Logged By: Karl Hewes v S1�1ample Type Penetration '� 3,'��. Description of Units Page 1 of 1 yResistance � a U p •`—' Note: The stratification lines shown represent the Y o T �D o ap proximate boundary between soil and/or rock types Graphic Trend p m (Blows/6") q U and the transition may be gradational. Blow Count Dry Density 3,3,4 , SM 95 5 SILTY SAND: grayish olive, medium dense,.dry, very fine grained, trace roots to 1/8" 3,4,5 105 14 SM/ML SILTY SAND: grayish olive, loose, damp, very fine to fine grained, trace roots to 1/8" 5,7,12 medium dense, becomes slightly less silty, trace roots to 5 1/4" 7.17,20 113 3 SP -SM SAND WITH SILT: light grayish olive, medium , dense 10 6,8,13 ML SILT: grayish olive, dense, moist, with clay and sand, very fine grained, non plastic 15 7,10,12 SM/ML SANDY SILT: moderate olive brown, medium dense, damp, very fine to fine grained 20 Total Depth 18.5 feet No groundwater encountered 25 30 35 en .Earth Systems �W Southwest 79-811 B Country Club Drive, Bermuda Dunes, CA 92201 Phone (760) 345-1588 FAX (760) 345-7315 Boring No: B-9 SILT: grayish olive, loose, damp, very fine grained, Drilling Date: August 1, 2003 Project Name: Coral Mountain, La Quinta, CA 6,5,4 Drilling Method: 8" Hollow Stem Auger File Number: 09305-01 96 3 trace thin roots, trace small marine shells Drill Type: CME 45 with cathead Boring Location: See Figure 2 5,6,7 Logged By: Karl Hewes SM/ML Sample Type Penetration _ Description of Units Page 1 of 1 Resistance E Q¢ o Y Note: The stratification lines shown represent the p CL N Y p �, SILT: grayish olive, loose to medium dense, damp ... c approximate boundary between soil and/or rock types Graphic Trend p a a o (Blows/6") mei Q U and the transition may be gradational. Blow Count D Density Dry h' -5 - 10 20 25 30 35 40 ML SILT: grayish olive, loose, damp, very fine grained, 6,5,4 96 3 trace thin roots, trace small marine shells 5,6,7 SM/ML 90 10 SILTY SAND: moderate olive brown, medium dense, moist, trace thin clay layers, non plastic trace 4,5,7 MLroots 77 19 to 1/8" diameter SILT: grayish olive, loose to medium dense, damp 5,7,8 73 29 • 4,6,8 SM/ML SANDY SILT: grayish olive; medium dense, damp, very fine to fine grained 4,4,6 SM SILTY SAND: light grayish olive, fine grained Total Depth 21.5 feet No groundwater encountered t' 0 Earth Systems 1r/ Southwest ML 79-811 B Country Club Drive, Bermuda Dunes, CA 92201 23 18 12 SILT: grayish olive, medium dense, damp, very fine grained, trace roots to 1/4" diameter, one piece of rsted, frletal debris . less silly, some orange staining moderate olive brown, very fine grained, sandy Phone (760) 345-1588 FAX (760) 345-7315 Boring No: B-10 sM SILTY SAND: light olive gray, medium dense, Drilling Date: August 1, 2003 Project Name: Coral Mountain; La Quinta, CA Drilling Method: 8" Hollow Stem Auger File Number: 09305-01 damp, fine grained, trace medium grained, trace Drill Type: CME 45 with cathead Boring Location: See Figure 2 Logged By: Karl Hewes v Sample Type,.; Penetration— Description of Units Page 1 of 1 arj Resistance 0 E U p a .o Note: The stratification lines shown represent the q (Blows/6") 7,12,13 a e approximate boundary between soil and/or rock types Graphic Trend medium dense, slightly finer grained m pkv U and the transition may be gradational. Blow Count Dry Density -5 10 15 20 25 30 —,35 40 4,8,9 5,7,12 5,10,18 8,17,21 ML 96 109 108 23 18 12 SILT: grayish olive, medium dense, damp, very fine grained, trace roots to 1/4" diameter, one piece of rsted, frletal debris . less silly, some orange staining moderate olive brown, very fine grained, sandy sM SILTY SAND: light olive gray, medium dense, damp, fine grained, trace medium grained, trace roots to 1/4" diameter 4,5,6 slightly darker to light grayish olive, loose 7,12,13 medium dense, slightly finer grained Total Depth 18.5 feet No groundwater encountered L Earth Systems �O, ' Southwest 5 10 15 20 25 30 35 40 79-811B Country Club Drive, Bermuda Dunes, CA 92201 Phone (760) 345-1588 FAX (760) 345-7315 Boring No: B41 SILTY SAND: grayish olive, medium dense, dry, Drilling Date: August 1, 2003 Project Name: Coral Mountain, La Quinta, CA 6,8,9 Drilling Method: 8" Hollow Stem Auger File Number: 09305-01 104 2 fine grained with trace medium grained, trace very thin roots, marine shells Drill Type: CME 45 with cathead Boring Location: See Figure 2 8'17'23 Logged By: Karl Hewes ML Sample Type Penetration 6 :_'' Description of Units Page 1 of] cJ' Resistance _ rn U c p a •= aci Note: The stratification lines shown represent the trace clay, non plastic, trace small voids, trace thin Y in T " o c approximate boundary between soil and/or rock types Graphic Trend O = a O (Blows/6") 2 roots, trace small marine shells p j and the transition may be gradational. Blow Count D Density �Y 5 10 15 20 25 30 35 40 SM/ML SILTY SAND: grayish olive, medium dense, dry, 6,8,9 104 2 fine grained with trace medium grained, trace very thin roots, marine shells 8'17'23 ML 99 6 SILT: light olive, dense, dry, very fine grained, trace clay, non plastic, trace small voids, trace thin 7,20,29 gM 98 2 roots, trace small marine shells SILTY SAND: moderate olive brown, dense, dry, very fine grained, some orange staining, trace thin roots 7,26,30 grayish olive 7,9,12 T. SM SILTY SAND: grayish olive, medium dense, dry, very silty, very fine to fine grained 10,12,12 less silty, some orange staining Total Depth 21.5 feet No groundwater encountered Earth Systems rMSF' Southwest 5 10 15 20 - 25 - 30 - 35 40 79-811 B Country Club Drive, Bermuda Dunes, CA 92201 Phone (760) 345-1588 FAX (760) 345-7315 Boring No: B -I2 ML 96 5 SILT: grayish olive dense dry, very fine grained, trace clay interlayers, non plastic, small marine Drilling Date: August 1, 2003 Project Name: Coral Mountain, La Quinta, CA 'Drilling Method: 8" Hollow Stem Auger File Number: 09305-01 96 5 shells, trace very thin roots moderate olive brown, sandy, trace laminations Drill Type: CME 45 with cathead Boring Location: See Figure 2 Logged By: Karl Hewes v Sample Type .Penetration 95 6 _ '� 3' Description of Units Page I of 1 o Resistance E � Q a •o Note: The stratification lines shown represent the P Q Y a (Blows/6") Q " e approximate boundary between soil and/or rock types Graphic Trend m En SILT: moderate olive brown, dense, dry, trace clay t j and the transition may be gradational. Blow Count Dry Density 5 10 15 20 - 25 - 30 - 35 40 7,14,15 ML 96 5 SILT: grayish olive dense dry, very fine grained, trace clay interlayers, non plastic, small marine 8,13,16 96 5 shells, trace very thin roots moderate olive brown, sandy, trace laminations 9,21,31 ML 95 6 SILT: light olive brown, hard, dry, no to very low plasticity, trace small voids, trace thin roots, some 5,9,8 ML laminations SILT: moderate olive brown, dense, dry, trace clay laminations, non plastic, very fine grained, trace small marine shells 8,9,13 SM SILTY SAND: light olive gray, medium dense, dry, T. fine grained 8.8.11 grayish olive Total Depth 18.5 feet No groundwater encountered Earth Systems r-%1Zftw? ' Southwest 5 10 15 20 25 30 35 40 79-811 B Country Club Dive, Bermuda Dunes, CA 92201 Phone (760) 345-1588 FAX (760) 345-7315 Boring No: B-13 ML SILT: grayish olive, medium dense, dry, very fine Drilling Date: August 1, 2003 Project Name: Coral Mountain, La Quinta, CA Drilling Method: 8" Hollow Stem Auger File Number: 09305-01 89 4 grained, trace clay laminations, trace small voids, trace thin roots, trace small marine shells Drill Type: CME 45 with cathead Boring Location: See Figure 2 Logged By: Karl Hewes v Sample Type Penetration a � Description of Units Page 1 of 1 aResistance CO U q 0 CL •o Y Note: The stratification lines shown represent the y p �, a " e approximate boundary between soil and/or rock types Graphic Trend a m � 0 (Blows/6") rn A j and the transition may be gradational. Blow Count Dry Density 5 10 15 20 25 30 35 40 ML SILT: grayish olive, medium dense, dry, very fine 5,8,8 89 4 grained, trace clay laminations, trace small voids, trace thin roots, trace small marine shells 7,21,31 SM 95 z SILTY SAND: moderate olive brown, dense, dry, very fine grained, trace thin roots, some orange 17,29,36 MUCL 99 5 staining CLAYEY SILT: moderate olive brown, hard, dry, low plasticity, trace small voids, trace decomposed roots to 1/4 " diameter, some laminated clay 15,25,37 SM SILTY SAND: grayish olive, very dense, dry, very fine to fine grained, trace very thin roots, trace small marine shells 8,12,13 ML SILT: grayish olive,dense, dry, very fine grained, some orange staining Total Depth 16.5 feet t No groundwater encountered Earth Systems W'Sout west CPT No: CPT-1 CPT Vendor: Holguin Fahan & Associates uJ Project Name: Coral Mountain Truck Mounted Electric ILL Project No.: 0305-01 Cone with 23-ton reaction x Location: See Site Exploration Plan Date: 4/15/2003 a W Friction Ratio (%) Tip Resistance, Qc (tsf) G' aphic Log (SBT) Interpreted Soil Stratigraphy Robertson & Campanella ('89) Density/Consistency 8 6 4 2 0 40 80 120 160 200 240 0; 12 Silty Sand to Sandy Silt dense Sandy Silt to Clayey Silt dense Sandy Silt to Clayey Silt very dense Sandy Silt to Clayey Silt very dense 5_ Clayey Silt to Silty Clay hard Silty Sand to Sandy Silt very dense Silty Sand to Sandy Silt very dense Silty Sand to Sandy Silt very dense Silty Sand to Sandy Silt very dense 10 Sandy Silt to Clayey Silt very dense Sandy Silt to Clayey Silt very dense Silty Sand to Sandy Silt very dense Silty Sand to Sandy Silt dense Sandy Silt to Clayey Silt medium dense Silty Sand to Sandy Silt very dense 15 Silty Sand to Sandy Silt very dense Silty Sand to Sandy Silt very dense Silty Sand to Sandy Silt very dense Silty Sand to Sandy Silt dense 20 Silty Clay to Clay hard Clay very stiff Sandy Silt to Clayey Silt loose Sandy Silt to Clayey Silt medium dense an Silt to Clayey Silt medium dense Silty Sand to Sandy Silt medium dense 25 Silty Sand to Sandy Silt dense Silty Sand to Sandy Silt medium dense Silty Sand to Sandy Silt medium dense Clayey Silt to Silty Clay hard 30 Clay very stiff Silty Clay to Clay stiff Silty Clay to Clay stiff Sandy Silt to Clayey Silt medium dense Sand to Silty Sand medium dense Sand to Silty Sand very dense r 35 Sand to Silty Sand dense Silty Sand to Sandy Silt medium dense Sandy Silt to Clayey Silt loose Silty Clay to Clay stiff 40 Clay stiff Clay very stiff Silty Clay to Clay stiff Clay very stiff Silty Clay to Clay hard 45 Silty Sand to Sandy Silt medium dense Silty Sand to Sandy Silt medium dense Silty Sand to Sandy Silt dense Sand to Silty Sand very dense Sand to Silty Sand very dense Sand to Silty Sand very dense End of Sounding @ 50.5 feet 50 Earth Systems P w Iu z CPT No: CPT -2 CPT Vendor: Holguin Fahan & Associates, Project Name: Coral Mountain Truck Mounted Electric Project No.: 0305-01 Cone with 23 -ton reaction Location: See Site Exploration Plan Date: 4/15/2003 ~ a I 0 Gra nic Lo SB Friction Ratio (%) Tip Resistance, Qc (tsf) G' 9 Interpreted Soil Stratigraphy g 6 4 2 0 40 80 120 160 200 240 0' 12 Robertson & Campanella ('89) Density/Consistency Silty Sand to Sandy Silt dense Sandy Silt to Clayey Silt medium dense Sandy Silt to Clayey Silt very loose Silty Sand to Sandy Silt very dense Silty Sand to Sandy Silt very dense Silty Sand to Sandy Silt very dense Sandy Silt to Clayey Silt dense Sandy Silt to Clayey Silt very dense Sandy Silt to Clayey Silt dense Clayey Silt to Silty Clay hard Clayey Silt to Silty Clay hard Sandy Silt to Clayey Silt dense Sandy Silt to Clayey Silt dense Sandy Silt to Clayey Silt dense Clayey Silt to Silty Clay hard Overconsolidated Soil medium dense Clay hard Sandy Silt to Clayey Silt medium dense Silty Sand to Sandy Silt dense Silty Sand to Sandy Silt dense Sandy Silt to Clayey Silt dense Sandy Silt to Clayey Silt dense Clayey Silt to Silty Clay hard Clayey Silt to Silty Clay hard Clayey Silt to Silty Clay hard Overconsolidated Soil medium dense Overconsolidated Soil medium dense Overconsolidated Soil medium dense Overconsolidated Soil medium dense Clayey Silt to Silty Clay hard Sandy Silt to Clayey Silt dense Sandy Silt to Clayey Silt medium dense Silty Sand to Sandy Silt medium dense Silty Sand to Sandy Silt medium dense Sandy Silt to Clayey Silt medium dense Sandy Silt to Clayey Silt medium dense Sandy Silt to Clayey Silt medium dense Sandy Silt to Clayey Silt medium dense Clayey Silt to Silty Clay hard Clay very stiff Clay very stiff Sandy Silt to Clayey Silt loose Silty Sand to Sandy Silt dense Sandy Silt to Clayey Silt medium dense Sandy Silt to Clayey Silt medium dense Clay hard Clay stiff Clay very stiff Clay stiff Clay stiff End of Sounding @ 51.0 feet FC F__ .-5- 110 15 F 20 25 30 35 40 145 Ir 50 Earth Systems out west P w ILLProject z CPT No: CPT -3 CPT Vendor: Holguin Fahan & Associates Project Name: Coral Mountain Truck Mounted Electric No.: 0305-01 Cone with 23 -ton reaction Location: See Site Exploration Plan Date: 4/15/2003 E- I Lu Friction Ratio (%) Tip Resistance, Qc (ts� Graphic Log (SBT) Interpreted Soil Stratigraphy g 6 4 2 0 40 80 120 160 200 240 0 12 Robertson & Campanella ('89) Density/Consistency Sandy Silt to Clayey Silt very dense Silty Sand to Sandy Silt very dense Sand to Silty Sand very dense Silty Sand to Sandy Silt very dense Silty Sand to Sandy Silt very dense Clayey Silt to Silty Clay hard Silty Clay to Clay hard Clayey Silt to Silty Clay hard Sandy Silt to Clayey Silt very dense Sandy Silt to Clayey Silt very dense Overconsolidated Soil medium dense Silty Clay to Clay hard Silty Sand to Sandy Silt very dense Silty Sand to Sandy Silt dense Sandy Silt to Clayey Silt medium dense Sandy Silt to Clayey Silt medium dense Sandy Silt to Clayey Silt medium dense Clayey Silt to Silty Clay hard Clayey Silt to Silty Clay hard Silty Clay to Clay hard Clayey Silt to Silty Clay hard Sandy Silt to Clayey Silt medium dense Sandy Silt to Clayey Silt medium dense Silty Sand to Sandy Silt medium dense Sandy Silt to Clayey Silt medium dense Silty Sand to Sandy Silt dense Sand to Silty Sand very dense Sand to Silty Sand very dense Sand to Silty Sand very dense Silty Sand to Sandy Silt dense Sandy Silt to Clayey Silt medium dense Silty Sand to Sandy Silt dense Sand to Silty Sand very dense Silty Sand to Sandy Silt dense Sandy Silt to Clayey Silt medium dense Clayey Silt to Silty Clay hard Sandy Silt to Clayey Silt medium dense Sandy Silt to Clayey Silt medium dense Sandy Silt to Clayey Silt medium dense Silty Sand to Sandy Silt medium dense Silty Sand to Sandy Silt medium dense Sandy Silt to Clayey Silt medium dense Clayey Silt to Silty Clay hard Overconsolidated Soil medium dense Overconsolidated Soil medium dense Sand to Clayey Sand dense Silty Clay to Clay hard Clayey Silt to Silty Clay hard Clayey Silt to Silty Clay hard Overconsolidated Soil medium dense End of Sounding @ 50.9 feet - 5 _ 10 15 20 25 30 35 40 45 50 Earth Systems out west CPT No: CPT -4 CPT Vendor: Holguin Fahan & Associates Lu Project Name: Coral Mountain Truck Mounted Electric ILu Project No.: 0305-01. Cone with 23 -ton reaction x Location: See Site Exploration Plan Date: 4/15/2003 a W Friction Ratio (%) Tip Resistance, Qc (tst) Graphic Log (SBT) Interpreted Soil Stratigraphy I g 6 4 2 0 40 80 120 160 200 240 0 12 Robertson & Campanella ('89) Density/Consistency Overconsolidated Soil very dense Clayey Silt to Silty Clay very stiff Sandy Silt to Clayey Silt loose Sandy Silt to Clayey Silt very loose -5- Clayey Silt to Silty Clay very stiff Sandy Silt to Clayey Silt dense Silty Sand to Sandy Silt very dense of Silty Sand to Sandy Silt very dense Silty Sand to Sandy Silt very dense 10 Silty Sand to Sandy Silt dense Clayey Silt to Silty Clay hard Silty Clay to Clay very stiff Clay firm Clay firm 15 Silty Clay to Clay hard •t Sand very dense . Sandy Silt to Clayey Silt dense Sandy Silt to Clayey Silt medium dense Clay very stiff - f 20 Clay very stiff Silty Clay to Clay very stiff ' Sandy Silt to Clayey Silt very loose Silty Sand to Sandy Silt medium dense Sandy Silt to Clayey Silt medium dense Sandy Silt to Clayey Silt medium dense " - 25 Silty Sand to Sandy Silt dense ' Silty.Sand to Sandy Silt very dense Silty Sand to Sandy Silt .very dense ' Silty Sand to Sandy Silt medium dense 30 Silty Sand to Sandy Silt dense 0 ' Clayey Silt to Silty Clay hard Clayvery stiff - Silty Clay to Clay very stiff Sand to Silty Sand medium dense Silty Sand to Sandy Silt .medium dense ,. _ 35 Sand to Silty Sand medium dense Sand to Silty Sand medium dense Silty Sand to Sandy Silt medium dense Clayey Silt to Silty Clay hard 40 Clay very stiff Clay very stiff Silty Clay to Clay stiff - - Silty Clay to Clay stiff Silty Clay to Clay stiff 45 Silty Clay to Clay stiff Clay very stiff Overconsolidated Soil medium dense Sand to Clayey Sand dense Silty Sand to Sandy Silt dense 50 Silty Sand to Sandy Silt dense End of Sounding @ 50.9 feet t Earth Systems ou F, W IUJI = CPT No: CPT -5 CPT Vendor: Holguin Fahan & Associates Project Name: Coral Mountain Truck Mounted Electric Project No.: 0305-01 Cone with 23 -ton reaction Location: See Site Exploration Plan Date: 4/15/2003 0- W Friction Ratio (%) Tip Resistance, Qc (tsf) Graphic Log (SBT) Interpreted Soil Stratigraphy g 6 4 2 0 40 80 120 160 200 240 0 12 Robertson & Campanella ('89) Density/Consistency Sandy Silt to Clayey Silt very dense Overconsolidated Soil dense Silty Clay to Clay hard Sandy Silt to Clayey Silt dense Overconsolidated Soil dense Overconsolidated Soil very dense Sandy Silt to Clayey Silt very dense Sandy Silt to Clayey Silt very dense Sand to Silty Sand very dense Sand to Silty Sand very dense Sand to Silty Sand very dense Sand to Silty Sand very dense Sand to Silty Sand very dense Silty Sand to Sandy Silt dense Silty Sand to Sandy Silt very dense Silty Sand to Sandy Silt very dense Silty Sand to Sandy Silt very dense Clayey Silt to Silty Clay hard Clayey Silt to Silty Clay hard Sandy Silt to Clayey Silt medium dense Sandy Silt to Clayey Silt dense Silty Sand to Sandy Silt very dense Silty Sand to Sandy Silt very dense Silty Sand to Sandy Silt very dense Silty Sand to Sandy Silt very dense Sand to Silty Sand very dense Sand to Silty Sand very dense Sand to Silty Sand very dense Sand to Silty Sand dense Sand to Silty Sand very dense Sand to Silty Sand very dense Clayey Silt to Silty Clay hard Silty Sand to Sandy Silt medium dense Silty Sand to Sandy Silt very dense Silty Sand to Sandy Silt dense Silty Sand to Sandy Silt dense Silty Sand to Sandy Silt dense Sandy Silt to Clayey Silt medium dense Silty Sand to Sandy Silt medium dense Silty Sand to Sandy Silt medium dense Silty Sand to Sandy Silt medium dense Clayey Silt to Silty Clay hard Silty Clay to Clay hard Clay very stiff Clay hard Clay very stiff Clay very stiff Clay very stiff Clay very stiff Clay very stiff End of Sounding @ 50.7 feet ,,::; -5 _ 10 15 20 25 _ 30 35 40 45 _ LJ 50 File No.: 09305-01 August 15, 2003 UNIT DENSITIES AND MOISTURE CONTENT ASTM D2937 & D2216 Job Name: Coral Mountain Unit Moisture USCS Sample Depth Dry Content Group Location (feet) Density (pcf) (%) Symbol B 1 1 75 2 ML B 1 3 89 5 ML BI 5 94 5 ML B1 10 97 9 ML B2 0 93 1 SM B2 2 99 1 SM/ML B2 4 102 1 SP -SM B3 1 88 B3 3 101 B3 5 96 r B4 0 105 B4 2 94 B4 4 105 B4 7 96 B4 12 97 B5 1 98 B5 3 98 B5 5 93 B6 0 98 B6 2 86 B6 4 83 B7 1 83 B7 3 94 B7 5 98 B7 10 85 EARTH SYSTEMS SOUTHWEST 0 SM 0 SM 1 SM 1 ML 3 ML 1 SP -SM 2 ML 16 CL 0 SM 2 SM 12 ML 6 ML 16 ML 29 ML� 24 ML 20 ML 14 ML 36 CL File -No.: 09305-01 August 15, 2003 UNIT DENSITIES AND MOISTURE CONTENT ASTM D2937 & D2216 Job Name: Coral Mountain B8 2 Unit Moisture USCS Sample Depth Dry Content Group Location (feet) Density (pcf) N Symbol B8 2 95 5 SM . B8 4 105 14 SM/ML B8 7 113 3 SP -SM - B9 1 96 3 ML B9 3 90 10 SM/ML B9 5 77 19 ML B9 10 73 29 ML 1310 0 96 23 ` ML B10 2 109 18 ML 1310' 4 108 12 ML 1311 1 104 2 SM/ML B l l 3 99 6 ML ` 1311 5 98 2 SM B12 0 96 5 ML B12 2 96 5 ML B12 5 95 6 ML B13 1 89 4 ML B13 3 95 2 SM B13 5 99 5 ML B13 10 107 3 SM EARTH SYSTEMS SOUTHWEST File No.: 09305-01 August 15, 2003 PARTICLE SIZE ANALYSIS ASTM D-422 Job Name: Coral Mountain Sample ID: B4 @ 7' Feet Description: Very Sandy Silt (ML) Sieve Percent ' Size Passing 1-1/2" 100 1" 100 3/4" 100 1'/2" 100 3/8" 100 #4 100 #8 100 #16 100 % Gravel: 0 #30 100 % Sand: 44 #50 98 % Silt: 45 #100 81 % Clay (3 micron): 10 #200 55 (Clay content by short hydrometer method) , 100 90 80 70 J I w 60 °' S0 c v 40 30- 20 10 0-- 100 10 1 0.1 0.01 0.001 Particle Size ( mm) EARTH SYSTEMS SOUTHWEST File No.: 09305-01 August 15, 2003 PARTICLE SIZE ANALYSIS ASTM D-422 Job Name: Coral Mountain Sample ID: Bl @ 0-5' Feet Description: Sandy Silt (ML) Sieve Percent Size Passing 1-1/2" 100 1" 100 3/4" 100 1/2" 100 3/8" 100 #4 100 #8 100 #16 100 % Gravel: 0 #30 99 % Sand: 27 #50 97 % Silt: 56 #100 89 % Clay (3 micron): 17 #200 73 (Clay content by short hydrometer method) 100 90 80 70 •. °G° 60 N R 50 c a ' V 40 30 20 10 0-- 100 10 1 0.1 0.01 , 0.001 Particle Size (mm) EARTH SYSTEMS SOUTHWEST • File No.: 09305-01 August 15, 2003 PARTICLE SIZE ANALYSIS ASTM D-422 Job Name: Coral Mountain Sample ID: B12 @ 0-5' Feet Description: Sandy Silt (ML) Sieve Percent Size Passing 1-1 /2" 100 1,t 100 3/4" 100 1/2" 100 ' 3/8" 100 #4 100 #8 100 #16 100 % Gravel: 10 #30 100 % Sand: 31 #50 99 % Silt: 50 " #100 92 % Clay (3 micron): 19 #200. 69 (Clay content by short hydrometer method) ' 100 90 80 70 °S 60 50 G Q) U 40 30 20 10 0 100 10 1 0.1 Particle Size ( mm) EARTH SYSTEMS SOUTHWEST, 0.01 0.001 • File No.: 09305-01 August 15, 2003 CONSOLIDATION TEST ASTM D 2435 & D 5333 Coral Mountain Initial Dry Density: #VALUE! BI @ 10' Feet Initial Moisture, %: 8.61/o .; Silt (ML) Specific Gravity (assumed): 2.67 Ring Sample Initial Void Ratio: #VALUE! Hydrocollapse: 0.6% @ 2.0 ksf % Change in Height vs Normal Presssure Diagram 2 1 0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 -11 -12 —9—Before Saturation ="zwr"V� Hydrocollapse ■ After Saturation —Rebound 0.1 1.0 r EARTH SYSTEMS SOUTHWEST 0 File No.: 09305-01 August 15, 2003 CONSOLIDATION TEST ASTM D 2435 & D 5333 Coral Mountain Initial Dry Density: 74.5 pcf B6 @ 4' Feet Initial Moisture, %: 29.5% Slit (ML) Specific Gravity (assumed): 2.67 Ring Sample Initial Void Ratio: 1.237 Hydrocollapse: 0.6% @ 2.0 ksf %. Change in Height vs Normal Presssure Diagram 2 0 -1 -2 -3 -5 -6 -7 -8 -9 -10 -11 -12 I 8 Before Saturation lapse ■ After Saturation Rebound 0.1 1.0 EARTH SYSTEMS SOUTHWEST File No.: 09305-01 August 15, 2003 CONSOLIDATION TEST ASTM D 2435 Coral Mountain Initial Dry Density: 82.6 pcf 137 @ 10' Feet Initial Moisture, %: 36.3% Silty Clay (CL) Specific Gravity (assumed): 2.67 Ring Sample Initial Void Ratio: 1.019 % Change in Height vs Normal Presssure Diagram --* Before Saturation ■ After Saturation —SIE --Rebound 2 1 0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 -11 -12 File No.: 09305-01 August 15, 2003 CONSOLIDATION TEST ASTM D 2435 & D 5333 Coral Mountain Initial Dry Density: 86.4 pcf 139 @ 10' Feet Initial Moisture, %: 28.7% Silt (ML) Specific Gravity (assumed): 2.67 Ring Sample Initial Void Ratio: 0.929 Hydrocollapse: 0.5% @ 2.0 ksf 2 1 0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 -11 -12 0.1 % Change in Height vs Normal Presssure Diagram —*—Before Saturation °' zz- ^l:Hydrocollapse ■ After Saturation -.-*--Rebound 1.0 10.0 EARTH SYSTEMS SOUTHWEST File No.: 09305-01 August 15, 2003 CONSOLIDATION TEST ASTM D 2435 & D 5333 Coral Mountain Initial Dry Density: 99.5 pcf B13 @ 10' Feet Initial Moisture, %: 2.7% Silty Sand: F to M (SM) Specific Gravity (assumed): 2.67 Ring Sample Initial Void Ratio: 0.675 Hydrocollapse: 1.7% @ 2.0 ksf % Change in Height vs Normal Presssure Diagram Before Saturation c,. , .... 4Hydrocollapse ■ After Saturation SIE—Rebound . 1 0 i -2 -3 4 -5 -6- -7- -8 -8 -9 -10 -11 -12 0.1 1.0 10.0 EARTH SYSTEMS SOUTHWEST File No.: 09305-01 August 15, 2003 MAXIMUM DENSITY / OPTIMUM MOISTURE ASTM D 1557-91 (Modified) Job Name: Coral Mountain Procedure Used: A Sample ID: B 1 @ 0-5' Feet Preparation Method: Moist Location: Native Rammer Type: Mechanical Description: Olive Brown: Sandy Silt (ML) Sieve Size % Retained Maximum Density: 118.5 pcf 3/4" 0.0 Optimum Moisture: 12% 3/8" 0.0 #4 .0.0 140- 135-- 130- 125 40135130 0 5 10 15 20 25 30 Moisture Content, percent F EARTH SYSTEMS SOUTHWEST 125 w U d w 120 C.' A • L A 115 110 105 100 0 5 10 15 20 25 30 Moisture Content, percent F EARTH SYSTEMS SOUTHWEST Fite No.: 09305-01 August 15, 2003 MAXIMUM DENSITY / OPTIMUM MOISTURE ASTM D 1557-91 (Modified) Job Name: Coral Mountain Procedure Used: A Sample ID: B12 @ 0-5' Feet Preparation Method: Moist Location: Native Rammer Type: Mechanical Description: Olive Brown: Sandy Silt (ML) Sieve Size % Retained Maximum Density: 118 pcf 3/4" 0.0 Optimum Moisture: 13% 3/8" 0.0 #4 0.0 140- 135-- 130-- < ----- 40135130<----- Zero Air Voids Lines, sg =2.65, 2,70, 2,75 125 � w U a A 115- 110-- 105-- 100 15110.105100 0 5 10 15 20 25 - Moisture Content, percent EARTH SYSTEMS SOUTHWEST t Chemical Agent Amount in Soil Degree of Corrosivity Soluble 0 -1000 ppm File No.: 09305-01 Sulfates 1000 - 2000 ppm Moderate July 28, 2003 SOIL CHEMICAL ANALYSES Severe > 5000 PPM Very Severe Resistivity 1-1000 ohm -cm Very Severe Job Name: Coral Mountain Severe 2000-10,000 ohm -cm Moderate Job No.: 09305-01 10,000+ ohm -cm Low Sample ID: #1 #2+3 #4+5 #6+7 #8+9 Sample Depth, feet: 0=1' 0-1' 0-1' 0-1' 0-1' H: pN/A N/A N/A N/A . N/A Resistivity (ohm -cm): 2,600 70 810 3,000 330 (saturated soil ) Chloride (Cl), ppm: N/A N/A N/A N/A N/A Sulfate (SOA ppm: N.D. 15,236 1,502 N.D 11,837 Note: Tests performed by Subcontract Laboratory: M.J. Schiff & Associates, Inc. 431 W. Baseline Road Claremont, CA 91711 Tel: (909) 626-3316 General Guidelines for Soil Corrosivitv Chemical Agent Amount in Soil Degree of Corrosivity Soluble 0 -1000 ppm Low Sulfates 1000 - 2000 ppm Moderate 2000 - 5000 ppm Severe > 5000 PPM 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 t EARTH SYSTEMS SOUTHWEST Y f', R File No.: 09305-01 July 28, 2003 SOIL CHEMICAL ANALYSES Job Name: Coral Mountain Job No.: 09305-01 Sample ID: #10 Sample Depth, feet: 0-1' pH: N/A Resistivity (ohm -cm): 900 (saturated soil ) Chloride' (Cl), ppm: N/A Sulfate (SO4), ppm: 452 Note: Tests performed by Subcontract Laboratory: M.J. Schiff & Associates, Inc. 431 W. Baseline Road Claremont, CA 91711 Tel: (909) 626-3316 General Guidelines for Soil Corrosivitv Chemical Agent Amount in Soil Degree of Corrosivity Soluble 0 -1000 ppm Low Sulfates 1000 - 2000 ppm Moderate 2000 - 5000 ppm Severe > 5000 ppm 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