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05-0116 (SFD) Geotechnical Engineering Report� s i f' i f . f• i, C Cn _ r N O OD Iti i • JUL .1 8 2008. By Consulting�Engineersbr d.Geologists- t_ O... j 1 t 1 1 1 1 1. 1 1 1 1 MR. BLAINE GRIMES P.O. BOX 5005 LA QUINTA, CALIFORNIA 92248 GEOTECHNICAL ENGINEERING REPORT PROPOSED SINGLE-FAMILY RESIDENCE 46-461 ROADRUNNER LANE LA QUINTA, CALIFORNIA November 22, 2005 FFE 1 2006 IUI © 2005 Earth Systems SouthwestBy Unauthorized use or copying of this document is strictly prohibite __ without the express written consent of Earth Systems Southwest. File No.: 10405-01 05-12-704 �j Earth Systems 1/ Southwest 79-811 B Country Club Drive Bermuda Dunes, CA 92203 (760) 345-1588 (800)924-7015 FAX (760) 345-7315 November 22, 2005 Mr. Blaine Grimes P.O. Box 5005 La Quinta, California 92248 Subject: Geotechnical Engineering.Report Project: Proposed Single -Family Residence 46-461 Roadrunner Lane La Quinta, California Dear Mr. Grimes: File No.: 10405-01 05-12-704 Earth Systems Southwest (ESSW) is pleased to present this geotechnical engineering report prepared for the proposed single-family residence to be located at 46-461 Roadrunner Lane in the City of La Quinta, Riverside County, California. The property is legally described as Assessors Parcel Number (APN) 600-041-015-7. 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. Extensive cuts are proposed in order to achieve finish pad grades, along with a series of retaining walls. The site is subject to strong ground motion from the San Andreas fault. This report should stand as a whole and no part of the report should be excerpted or used to the exclusion of any other part. This report completes our scope of services in accordance with our agreement:. dated October 27, 2005. Other services that may be required, such as plan review and grading observation, are additional services and will be billed according to our Fee Schedule in effect at the time services are provided. Unless requested in writing, the client is responsible for distributing this report to the appropriate governing agency or other members of the design team. We appreciate the opportunity to provide our professional services. Please contact our office if there are any questions or comments concerning this report or its recommenda_ions. Respectfully submitted, EARTH SYSTEMS SOUTHWEST o�pFESSIpNq tiC �2' �c 2 Crai S. Hill g �' `" ` m �', N No. 2266 T CE 38234 Cr EXP. 6-30- SER/rk/csh/ajf r,; � sT�F�TECNN��' Distribution: 6/Mr. Blaine Grimes SrE Oo� 1/RC File 2/BD File EARTH SYSTEMS SOUTHWEST i ' TABLE OF CONTENTS ' Page EXECUTIVESUMMARY........................................................................................... ii 1 Section 1 INTRODUCTION............................................................................................1 1.1 Project Description.............................................................................................1 1.2 Site Description..................................................................................................1 ' 1.3 Purpose and Scope of Work...............................................................................2 Section 2 METHODS OF INVESTIGATION.......................................... _ ................... 3 2.1 Field Exploration.........................................................................._...................3 2.2 Laboratory Testing........................................................................ _ ................... 3 Section3 DISCUSSION.............................................................................._...................4 ' 3.1 Soil Conditions............................................................................._....................4 3.2 Groundwater................................................................................._...................4 3.3 Geologic Setting............................................................................_...................4 3.4 Geologic Hazards.........................................................................._...................5 3.4.1 Seismic Hazards................................................................_...................5 3.4.2 Secondary Hazards............................................................ _ ................... 6 3.4.3 Site Acceleration and Seismic Coefficients...................... _ ................... 7 Section4 CONCLUSIONS........................................................................._...................8 ' Section 5 RECOMMENDATIONS............................................................_...................9 SITE DEVELOPMENT AND GRADING............................................... _ ................... 9 5.1 Site Development — Grading......................................................... _................... 5.2 Excavations and Utility Trenches................................................. _................. 10 5.3 Slope Stability of Graded Slopes.....................................................................10 STRUCTURES......................................................................................... _ ................. 11 5.4 Foundations.......................................................................................................11 5.5 Slabs-on-Grade.................................................................................................12 5.6 Retaining Walls.................................................................................................13 5.7 Mitigation of Soil Corrosivity on Concrete.....................................................14. 5.8 Seismic Design Criteria...................................................................................14 ' Section 6 LIMITATIONS AND ADDITIONAL SERVICES....................................16 6.1 Uniformity of Conditions and Limitations.......................................................16 6.2 Additional Services..........................................................................................17 ' REFERENCES...........................................................................................................18 APPENDIX A Figure 1 — Site Location Map Figure 2 — Boring Location Map Table 1 — Fault Parameters ' Terms and Symbols used on Boring Logs Soil Classification System Logs of Borings Seismic Analysis Result APPENDIX B 1 Laboratory Test Results EARTH SYSTEMS SOUTHWEST November 22, 2005 ' Section 1 INTRODUCTION 1 GEOTECHNICAL ENGINEERING REPORT PROPOSED SINGLE-FAMILY RESIDENCE 46-461 ROADRUNNER LANE LA QUINTA, CALIFORNIA 1.1 Project Description File No.: 10405-01 05-12-704 This geotechnical engineering report has been prepared for the proposed single family residence ' to be located at 46-461 Roadrunner Lane in the City of La Quinta, Riverside County, California. The proposed residence will be a two-story structure. We understand that the proposed structure will be of wood frame and masonry block. The extension of the wood -frame portion of the house will have a stucco finish. The structure should be supported by conventional shallow continuous or pad footings connected with grade beams, or a structural mat foundation. Site development will include, clearing and grubbing of vegetation, site grading, building pad 1 preparation, underground utility installation, and concrete driveway and sidewalks placement. Based on the existing sloping profile of the site and proposed pad elevations, cuts within the building pad will range from 2.5 to 10.5 feet to achieve the pad grade. For uniform bearing conditions, additional 3 feet of over -excavation and recompaction has been recommended below the pad grade. ■ Retaining walls up to about 11 feet in height are also proposed near the western and northern property limits. Grading plans show that the retained backfill will be almost level. Exterior walls of the house along its western and northern edges will also serve as retaining walls. We used maximum column loads of 30 kips and a maximum wall loading of 2 kips per linear foot as a basis for the foundation recommendations. All loading is assumed to be dead plus actual live load. If actual structural loading exceeds these assumed values, we would need to reevaluate the given recommendations. ■ 1.2 Site Description ' The proposed lot is irregularly shaped and located at the northwest corner of Cortez Lane and Roadrunner Lane in La Quinta, California. The site location is shown on Figure 1 in Appendix A. ' The project site is presently vacant. The site has a descending gradient sloping from northwest to south/south-east. The grade change is in the order of about 17 feet. Vegetation consists of some dried weeds and scattered grass. Active irrigation lines exist on the lot. The property is fenced along its northern and western boundaries. The history of past use and development of the property was not investigated as part of our scope ' of services. Buried remnants, such as old foundations, slabs, or septic systems, may exist on the site. There are 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 1 lines. rEARTH SYSTEMS SOUTHWEST 4 November 22, 2005 2 File No.: 10405-01 1 05-12-704 ' 1.3 Purpose and Scope of.Work The purpose for our services was to evaluate the site soil conditions and to prcvide professional opinions and recommendations regarding the proposed development of the si _e. The scope of ., work included the following: ' ➢ A general reconnaissance of the site. ➢ Shallow subsurface exploration by drilling three exploratory borings to depths ranging from 14 to 31.5 feet below existing grade. ' ➢ Laboratory testing of selected soil samples obtained from the explorator" borings. ➢ A review of selected published technical literature pertaining to the site.. ➢ An engineering analysis and evaluation of the acquired data from th . exploration and testing programs. ➢ A summary of our findings and recommendations in this written report. ' This report contains the following: ➢ Discussions on subsurface soil and groundwater conditions. ➢ Discussions on regional and local geologic conditions. ' ➢ Discussions on geologic and seismic hazards. ➢ Graphic and tabulated results of laboratory tests and field studies. ➢ Recommendations regarding: • Site development and grading criteria. • Excavation conditions and buried utility installations. • 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. ' Not Contained in This Report: Although available through Earth Systems Southwest, the current scope of our services does not include: 1 ➢ A corrosive study to determine cathodic protection of concrete or buried pipes. ➢ An environmental assessment. ➢ An investigation for the presence or absence of wetlands, hazardous of toxic materials in 1 the soil, surface water, groundwater, or air on, below, or adjacent to the subject property. The client did not direct ESSW to provide any service to investigate or detect the presence of 1 moisture, mold, or other biological contaminates in or around any structure, or any service that was designed or intended to prevent or lower the risk or the occurrence of tide amplification of the same. Client acknowledges that mold is ubiquitous to the environment, with mold ' amplification occurring when building materials are impacted by moisture. Client further acknowledges that site conditions are outside of ESSW's control and that mold amplification will likely occur or continue to occur in the presence of moisture. As such, ESSW cannot and shall 1 not be held responsible for the occurrence or recurrence of mold amplification. ' EARTH SYSTEMS SOUTHWEST November 22, 2005 3 Fire No.: 10405-01 ' 05-12-704 Section 2 METHODS OF INVESTIGATION 2.1 Field Exploration Three exploratory borings were drilled to depths ranging from 14 to 31.5 feet below the existing ' ground surface to observe the soil profile and to obtain samples for laboratory testing. The borings were drilled on November 1, 2005 using 8 -inch outside diameter hollow -stem augers, powered by a Mobile B61 truck -mounted drilling rig. The boring locations are shown on the ' boring location map, Figure 2, in Appendix A. The locations shown are approx (mate, 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 automatic hammer, dropping 30 inches in general accordance with ASTM D 1586. Recovered soil sampl; s were sealed in containers and returned to the laboratory. Bulk samples were also obtained from auger cuttings, representing a mixture of soils encountered at the depths noted. ' The final logs of the borings represent our interpretation of the contents of the field logs and the results of laboratory testing performed on the samples obtained during the subsurface exploration. The final logs are included in Appendix A of this report. The .stratification lines represent the approximate boundaries between soil types, although the transitions may be gradational. I2.2 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: 1 ➢ In-situ Moisture Content and Unit Dry Weight for the ring samples. ➢ Maximum density tests to evaluate the moisture -density relationship of typical soils encountered. ' ➢ Particle Size Analysis to classify and evaluate soil composition. The gradation characteristics of selected samples were made by hydrometer and sieve analysis procedures. ' ➢ Consolidation (Collapse Potential) to evaluate the compressibility and. hydroconsolidation (collapse) potential of the soil. ' ➢ Chemical Analyses (Soluble Sulfates and Chlorides, pH, and Electrical Resistivity) to evaluate the potential adverse effects of the soil on concrete and steel. EARTH SYSTEMS SOUTHWEST L November 22, 2005 4 File No. 10405-01 05-12-704 Section 3 DISCUSSION 3.1 Soil Conditions The field exploration indicates that site soils consist generally of sands with s:.lt, and silty sands (Unified Soils Classification System symbols of SP -SM and SM.). ' 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-1-13 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 0.6% to 0.7% collapse upon inundation and collapse is therefore considered a low 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 _natter (PM10) can create an air quality hazard if dust is blowing. Watering the surface, planting grass or ' landscaping, or placing hardscape normally mitigates this hazard. 3.2 Groundwater ' Free groundwater was not encountered in the borings during exploration. The depth to groundwater in the area is believed to be about 99 feet (El -39 feet) based on 1986 water well data obtained from the Coachella Valley Water District. However, there is uncertainty in the accuracy of short-term water level measurements. Groundwater levels nay 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. Groundwater should not be a factor in design or construction at this site. 3.3 Geologic Setting Regional Geology: The site lies within the Coachella Valley, a part of the Colorado Desert geomorphic province. A significant feature within the Colorado Desert geornorphic province is ' the Salton Trough. The Salton Trough is a large northwest -trending structural depression that extends approximately 180 miles from the San Gorgonio Pass to the Gulf of California. Much of this depression in the area of the Salton Sea is below sea level. The Coachella Valley forms the northerly part of the Salton Trough. Th.,- Coachella Valley contains a thick sequence of Miocene to Holocene sedimentary deposits. Mo-zntains 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 GeolgW: The project site is located less than 0.25 miles north of th.- Whitewater River channel and 70 feet above mean sea level in the central part of the Coachella Valley: The EARTH SYSTEMS SOUTHWEST ' November 22, 2005 5 File No.: 10405-01 05-12-704 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. The depth to crystalline basement rock beneath the site is estimated to be in excess of 2000 feet (Envicom, 1976). 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 hazardsa, slope instability, flooding, ground subsidence, and erosion. A discussion follows on the specific hazards to this ' site. 3.4.1 Seismic Hazards ' Seismic Sources: Several active faults or seismic zones lie within 62 miles (100 kilometers) of the project site as shown on Table 1 in Appendix A. The primary seismic hazard to the site is strong ground shaking from earthquakes along the San Andreas faults. The Maximum Magnitude Earthquake (Morax) listed is from published geologic information available for each fault (Cao et al., CGS, 2003). The Morax corresponds to the maximum earthquake believed to be tectonically possible. Surface Fault Rupture: The project site does not lie within a currently delineated State of California, Alquist-Priolo Earthquake Fault Zone (Hart, 1997). Well -delineated fault lines cross through this region as shown on California Geological Survey (CGS) maps (Jennings, 1994); however, no active faults are mapped in the immediate vicinity of the site. Th,-refore, active fault rupture is unlikely to occur at the project site. While fault rupture would most likely occur along previously established fault traces, future fault rupture could occur at other locations. Historic Seismicity: Six historic seismic events (5.9 M or greater) have significantly affected the Coachella Valley in the last 100 years. They are as follows: • Desert Hot Springs Earthquake — On December 4, 1948, a magnituce 6.5 ML (6.OMw) earthquake occurred east of Desert Hot Springs. This event was strongly felt in the Palm ' Springs area. • Palm Springs Earthquake — A magnitude 5.9 ML (6.2MW) earthquake =occurred on July 8, 1986 in the Painted Hills, causing minor surface creep of the Banning Segment of the San ' Andreas fault. This event was strongly felt in the Palm Springs area and caused structural damage, as well as injuries. • Joshua Tree Earthquake — On April 22, 1992, a magnitude 6.1 ML (6.1Mw) earthquake ' occurred in the mountains 9 miles east of Desert Hot Springs. Structura; damage and minor injuries occurred in the Palm Springs area as a result of this earthquake. • Landers and Big Bear Earthquakes — Early on June 28, 1992, a magnitude 7.5 Ms (7.3MW) ' earthquake occurred near Landers, the largest seismic event in Southern California for 40 years. Surface rupture occurred just south of the town of Yucca Valley and extended some 43 miles toward Barstow. About three hours later, a magnitude 6.6 Ms (6.4MW) 1 earthquake occurred near Big Bear Lake. No significant structural damage from these earthquakes was reported in the Palm Springs area. • Hector Mine Earthquake — On October 16, 1999, a magnitude 7.1MW earthquake occurred on ithe Lavic Lake and Bullion Mountain faults north of Twentynine Palms. While this event was widely felt, no significant structural damage has been reported in the Coachella Valley. EARTH SYSTEMS SOUTHWEST I November 22, 2005 6 File No.: 10405-01 05-12-704 Seismic Risk: While accurate earthquake predictions are not possible, various agencies have conducted statistical risk analyses. In 2002, the California Geological Surv:y (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 ris:{ at the site. The Working Group of California Earthquake Probabilities (WGCEP, 1995) estimated a 22% conditional probability that a magnitude 7 or greater earthquake may occur between 1994 and ' 2024 along the Coachella segment of the San Andreas fault. The primary seismic risk at the site is a potential earthquake along the San Andreas fault. Geologists believe that the San Andreas fault has characteristic earthquakes that result from rupture of each fault segment. The estimated characteristic earthquake is ma,piitude 7.7 for the Southern Segment of the fault (USGS, 2002). This segment has the longest --lapsed time since ' rupture of any part of the San Andreas fault. The last rupture occurred about 1690 AD, based on dating by the USGS near Indio (WGCEP, 1995). This segment has also ruptured on about 1020, 1300, and 1450 AD, with an average recurrence interval of about 220 years. The San Andreas fault may rupture in multiple segments, producing a higher magnitude earthquake. Recent paleoseismic studies suggest that the San Bernardino Mountain Segment to, the north and the Coachella Segment may have ruptured together in 1450 and 1690 AD (WGCEP, 1995). 3.4.2 Secondary Hazards Secondary seismic hazards related to ground shaking include soil licuefaction, 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 w-Ahin 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 considered negligible because the depth of groundwater beneath the site exceeds 50 feet. No free groundwater was encountered in our exploratory borings. In addition, the project does not lie within the Riverside County designated liquefaction hazard zone. ' Ground Subsidence: The potential for seismically induced ground subsidence is considered to be moderate at the site. Dry sands tend to settle and densify when subjected to strong earthquake shaking. The amount of subsidence is dependent on relative density of the soil, ground motion, ' and earthquake duration. Uncompacted fill areas may be susceptible to seismically induced settlement. Based on Tokimatsu and Seed methodology, we estimate that about 2 inches of total ground subsidence may occur in the upper 31.5 feet of soils for the Desig-i Basis Earthquake ' ground motion. Slope Instability: The site will be relatively flat after grading. Therefore, po_ential hazards from slope instability, landslides or debris flows are considered negligible. ' Floodins: The project site does not lie within a designated FEMA 10) -year flood plain. However, the site is located within a designated FEMA 500 -year flood plain. Hence, the project ' site may be in an area where sheet flooding and erosion could occur. If sigaificant changes are proposed for the site, appropriate project design, construction, and maintenance can minimize the site sheet flooding potential. EARTH SYSTEMS SOUTHWEST November 22, 2005 7 File No.: 10405-01 05-12-704 3.4.3 Site Acceleration and Seismic Coefficients Site Acceleration: The potential intensity of ground motion may be estimated by the horizontal peak ground acceleration (PGA), measured in "g" forces. Included in Table 1 are deterministic estimates of site acceleration from possible earthquakes at nearby faults. Ground motions are dependent primarily on the earthquake magnitude and distance to the seismogenic (rupture) zone. Accelerations are also dependent upon attenuation by rock and soil deposits, direction of rupture, and type of fault. For these reasons, ground motions may vary considerably in the same general area. This variability can be expressed statistically by a standard deviation about a mean relationship. The PGA alone is an inconsistent scaling factor to compare to the CBC Z factor and is generally a poor indicator of potential, structural damage during an earthquake. Important factors influencing the structural performance are the duration and frequency of strong ground motion, local subsurface conditions, soil -structure interaction, and structural details The following table provides the probabilistic estimate of the PGA taken from the 2002 CGS/USGS seismic hazard maps. Estimate of PGA from 2002 CGS/USGS Prohahilistie Seismic F4n7.nrd Mnnc Risk TPeriod Equivalent Return (years) PGA' t 10% exceedance in 50 years f 475 0.60 lvotes: 1. Based on a Soil Profile Type Sp. 2001 CBC Seismic Coefficients: The California Building Code (CBC) seismic design criteria are based on a Design Basis Earthquake (DBE) that has an earthquake ground motion with a 10% probability of occurrence in 50 years. The PGA estimate given above is provided for information on the seismic risk inherent in the CBC design. The seismic and site 'coefficients given in Chapter 16 of the 2001 California Building Code are provided in Section 5.8 of this report and below. 2001 CBC Seismic Coefficients for Chapter 16 Seismic Provisions Seismic Hazard Zones: The site does not lie within a liquefaction, landslide, or fault rupture hazard area or zone established by the 2002 Riverside County General Plan. Riverside County has not been mapped by the California Seismic Hazard Mapping Act (Ca. PRC 2690 to 2699). EARTH SYSTEMS SOUTHWEST Reference Seismic Zone: 4 Figure 16-2 Seismic Zone Factor, Z: 0.4 Table 16-I Soil Profile Type: SD Table 16-J Seismic Source Type: A Table 16-U Closest Distance to Known Seismic Source: 8.0 km = 5.0 miles (San Andreas fault) Near Source Factor, Na: 1.08 Table 16-S Near Source Factor, Nv: 1.36 Table 16-T Seismic Coefficient, Ca: 0.47 = 0.44Na Table 16-Q Seismic Coefficient, Cv: 0.87 = 0.64Nv Table 16-R Seismic Hazard Zones: The site does not lie within a liquefaction, landslide, or fault rupture hazard area or zone established by the 2002 Riverside County General Plan. Riverside County has not been mapped by the California Seismic Hazard Mapping Act (Ca. PRC 2690 to 2699). EARTH SYSTEMS SOUTHWEST November 22, 2005 8 File No.: 10405-01 ' 05-12-704 Section 4 CONCLUSIONS ' The following is a summary of our conclusions and professional opinions based on the data obtained from a review of selected technical literature and the site evaluation. ' General: ➢ From a geotechnical perspective, the site is suitable for the proposed development, ' provided the recommendations in this report are followed in the design and construction of this project. ' Geotechnical Constraints and Mitigation: ➢ The primary geologic hazard is severe ground shaking from earthquakes originating on nearby faults. A major earthquake above magnitude 7 originating on the local segment of the San Andreas fault zone would be the critical seismic event that may affect the site within the design life of the proposed development. Engineered design and earthquake - resistant construction increase safety and allow development of seismic areas. ➢ The project site is in seismic Zone 4, is of soil profile Type SD, and is about 8.0 km from a Type A seismic source as defined in the California Building Code.. A qualified ' professional should design any permanent structure constructed on the site. The minimum seismic design should comply with the 2001 edition of the California Building Code. ' ➢ Ground subsidence .from seismic events or hydroconsolidation is a potential hazard in the Coachella Valley area. Adherence to the grading and structural recommendations in this report should reduce potential settlement problems from seismic forces, heavy rainfall or ' irrigation, flooding, and the weight of the intended structures. The soils are susceptible to wind and water erosion. Preventative measures to reduce ' seasonal flooding and erosion should be incorporated into site grading plans. Dust control should also be implemented during construction. Site grading should be in strict compliance with the requirements of the South Coast Air Quality Management District (SCAQMD). ➢ Other geologic hazards, including fault rupture, liquefaction, seismically induced flooding, and landslides, are considered low or negligible on this site. ' ➢ We have estimated that about 2 inches of seismically induced subsidence may occur in the upper 31.5 feet for the design basis earthquake ground motion. Refer section 5.0 for ' grading and foundation design recommendations. ➢ Extensive cuts are proposed across the site. Upon excavation, the soils within the building and structural areas will require moisture conditioning, additional over -excavation and ' recompaction to improve bearing capacity and reduce the potential for differential settlement from static loading. Soils can be readily cut by normal grading equipment. iEARTH SYSTEMS SOUTHWEST 1 November 22, 2005 9 File No.: 10405-01 05-12-704 Section 5 RECOMMENDATIONS SITE DEVELOPMENT AND GRADING 5.1 Site Development — Grading A representative of Earth Systems Southwest (ESSW) should observe site clearing, grading, and ' the bottoms of excavations before placing fill. Local variations in soil conditions may warrant increasing the depth of recompaction and over -excavation. Clearing and Grubbing: At the start of site grading, existing vegetation,, large roots, 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: Based on the grading plan provided to our office. current elevations within the proposed building pad range from about 70.5 at the northwestern end to 62 at the southern end. Since the proposed pad grade elevation is 60.2, cuts depths will. vary from approximately 2.5 to 10.5 feet. A uniform thickness of engineered fill shoLld be achieved, as elevations across the building pad are the same. In the event that the proposes. grades are altered, our office should be contacted to review and revise, if needed, grading recommendations. In order to provide a uniform bearing surface for the foundations, we recommend additional over -excavation and recompaction of soils in the building area once the initial cuts are made. The soils within the building pad and foundation areas should be over -excavated to a minimum of 3 feet below the proposed pad grade or a minimum of 2 feet below the footing level (whichever is lower). The over -excavation should extend for 5 feet beyonc the outer edge of exterior footings along that portion of the house that parallels Roadrunner Lane. The bottom of the sub -excavation should be scarified, moisture conditioned and recompac:ed to at least 90% relative compaction (ASTM D 1557) for an additional depth of 6 inches. It may be possible for the grading contractor to make a partial over -excavation or compact from the finish grade elevation. The success of this method is dependant upon adequate moist --ire penetration and compaction effort. In any event, a representative of ESSW should verify the depths of moisture penetration and density by testing. Retaining Wall Subgrade Preparation: Retaining walls 3 to 6 feet in height are proposed near the ' western and northern property lines. The soils within the retaining wall four_dation areas should be over -excavated to at least 2 feet below bottom of footing. The lateral extent of the over - excavation needs to 5 feet beyond the face of the footing, where permissible. ' Auxiliary Structures Subgrade Preparation: Auxiliary structures such as. garden walls should have the foundation subgrade prepared similar to the retaining wall subgrade recommendations ' given above. The lateral extent of the over -excavation needs to extend only 2 feet beyond the face of the footing. 1 EARTH SYSTEMS SOUTHWEST November 22, 2005 10 File No.: 10405-01 05-12-704 Subgxade Preparation: In areas to receive fill, pavements or hardscape, the subgrade should be scarified, moisture conditioned and compacted to at least 90% relative compaction (ASTM D 1557) for a depth of 1 foot below finished subgrades. Compaction should be verified by testing. Engineered Fill Soils: The native soil is suitable for use as engineered fill and utility trench backfill, provided it is free of significant organic or deleterious matter. The native soil should be placed in maximum 8 -inch lifts (loose) and compacted to at least 90% relative compaction (ASTM D 1557) near its optimum moisture content. Compaction should be -erified by testing. Rocks larger than 6 inches in greatest dimension should be removed from fill or backfill material. 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 evalLate 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 5 tc 10 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 be less than 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 CaIOSHA requirements. Our site exploration and knowledge of the general area indicates there is a potential for caving of site excavations (utilities, footings, etc.). Excavations within sandy soil should be kept moist, but not saturated, to reduce the potential of caving or sloughing. Where excavations over 4 feet deep are planned, lateral bracing or appropriate cut slopes of 1.5:1 (horizontal:vertical) should be provided. No surcharge loads from stockpiled soils or construction materials should be allowed within a horizontal distance measured from the top of the excavation slope and equal to the depth of the excavation. Utility Trenches: Backfill of utilities within roads or public right-of-ways Should be placed in conformance with the requirements of the governing agency (water dis:rict, 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. EARTH SYSTEMS SOUTHWEST ' November 22, 2005 11 File No.: 10405-01 05-12-704 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). STRUCTURES ' The foundations and structures should be designed to accommodate the estimated seismically induced settlement as a means of mitigating the ground subsidence from the settling of dry sands as described in Section 3.4. '5.4 Foundations 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. 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 compacted soils as described in Section 5.1. Allowable bearing pressures are net (weight of footing and soil surcharge may be neglected). ' ➢ Continuous wall and grade beam connected pad foundations, 12 -inch minimum width and 12 inches below grade: 1500 psf for dead plus design live loads Allowable increases of 150 psf per each foot of additional footing width and 150 psf for each additional 0.5 foot of footing depth may be used up to a maximum value of 2,000 psf. ' ➢ Isolated footings are not recommended. However, in the event that isolated footings are provided, the foundations should use grade beam footings to tie floor slabs and isolated columns to continuous footings, designed to accommodate the estimated differential settlement of 1 -inch in a 20 -foot span (1:240 angular distortion ratio). A one-third (1/3) 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. IEARTH SYSTEMS SOUTHWEST November 22, 2005 12 File No.: 10405-01 05-12-704 ' Expected Settlement: Estimated total static settlement should be less than 1 inch, based on footings founded on firm soils as recommended. Differential settlement between exterior and interior bearing members should be less than '/z inch, expressed in a post -construction angular ' distortion ratio of 1:480 or less. Settlement induced from ground subsidence may be about 2 inches total in t= -ie upper 31.5 feet ' expressed in a post -construction angular distortion ratio of 1:240 or less. Additionally, utility connections to the structure should be flexible, able to accommodate this movement. 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 wa=ls. An allowable coefficient of friction of 0.35 of dead load may be used. An allowable�assive 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 to 0.23 of dead load forces. 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 any required backfill adjacent 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 .he slab. For these areas, an impermeable membrane (10 -mil thickness) should underlie the floor slabs. The ' membrane should be covered with 2 inches of sand to help protect it during construction and to aid in concrete curing. The sand should be lightly moistened just prior to placing the concrete. Low -slump concrete should be used to help reduce the potential for concrete shrinkage. The effectiveness of the membrane is dependent upon its quality, the method A overlapping, its protection during construction, and the successful sealing of the membrane around utility lines. The following minimum slab recommendations are intended to address geotechnical concerns ' such as potential variations of the subgrade and are not to be construed as superseding any structural design. ' Slab Thickness and Reinforcement: Slab thickness and 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 250 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 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. IEARTH SYSTEMS SOUTHWEST November 22, 2005 13 File No.: 10405-01 05-12-704 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 ' %2 -inch dowels at 18 -inches on center or a thickened keyed -joint to resist vertical deflection at the joint. All construction joints in exterior flatwork should be sealed to reduce the potential of moisture or foreign material intrusion. These procedures will reduce the potential for randomly ' oriented cracks, but may not prevent them from occurring. Curing and Quality Control: The contractor should take precautions to reduce the potential of curling of slabs in this and desert region using proper batching, placement, and curing methods. Curing is highly affected by temperature, wind, and humidity. Quality control procedures may be used, including trial batch mix designs, batch plant inspection, and on-site special inspection and ' testing. Typically, for this type of construction and using 2500 -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 1 Granular Backfill Passive Pressure 375 pcf - level ground Active Pressure (cantilever walls) Use when wall is permitted to rotate 0.1 % of wall height 37 pcf - level ground At -Rest Pressure restrained walls 55 pcf - level ground Dynamic Lateral Earth Pressure 2 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 1N V 105: 1. 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. Drainaie: 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 EARTH SYSTEMS SOUTHWEST November 22, 2005 14 File No.: 10405-01 05-12-704 ' 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. Backfill and Subgrrade 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. For-ndation subgrade preparation should be as specified in Section 5.1. 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 a low sulfate ion concentration (3 ppm) and a low chloride ion concentration (19 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 Califomia Building Code does not require any special provisions for concrete for these low concer_trations as tested. ' Normal concrete mixes may be used. A minimum concrete cover of three (3) inches should be provided around steel reinforcing or embedded components exposed to native soil or landscape water. Additionally, the concrete ' should be thoroughly vibrated during placement. Electrical resistivity testing of the soil (5,200 ohm -cm) suggests that the site soils may present a moderate potential for metal loss from electrochemical corrosion processes. Corrosion protection of steel can be achieved by using epoxy corrosion inhibitors, asphalt coatings, cathodic protection, or encapsulating with densely consolidated concrete. ' The information provided above should be considered preliminary. These values can potentially change based on several factors, such as importing soil from another job site and the quality of construction water used during grading and subsequent landscape irrigation. Earth Systems does not practice .corrosion engineering. We recommend that a qualified corrosion engineer evaluate the corrosion potential on metal construction materials and concrete ' at the site to provide mitigation of corrosive effects, if further guidance is desired. 5.8 Seismic Design Criteria This site is subject to strong ground shaking due to potential fault movements along the San Andreas 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 November 22, 2005 15 _pile No.: 10405-01 ' 05-12-704 2001 CBC Seismic Coefficients for Chapter 16 Seismic Provisions Reverence Seismic Zone: 4 Figure 16-2 Seismic Zone Factor, Z: 0.4 Table 16-I Soil Profile Type: SD Table 16-J ' Seismic Source Type: A Table 16-U Closest Distance to Known Seismic Source: 8.0 km = 5.0 miles (San Andreas fault) Near Source Factor, Na: 1.08 Table 16-S ' Near Source Factor, Nv: 1.36 Table 16-T Seismic Coefficient, Ca: 0.47 = 0.44Na Table 16-Q Seismic Coefficient, Cv: 0.87 = 0.64Nv Table 16-R ' The CBC seismic coefficients are based on scientific knowledge, engineering judgment, and compromise. - If further information on seismic design is needed, a site-specific probabilistic seismic analysis should be conducted. The intent of the CBC lateral force requirements is to provide a structural design that will resist ' collapse to provide reasonable life safety from a major earthquake, but may experience some structural and nonstructural damage. A fundamental tenet of seismic design is that inelastic yielding is allowed to adapt to the seismic demand on the structure. In other words, damage is ' allowed. The CBC lateral force requirements should be considered a minimum design. The owner and the designer should evaluate the level of risk and performance that is acceptable.. Performance based criteria could be set in the design. The design engineer should exercise 1 special care so that all components of the design are fully met with attention to providing a continuous load path. An adequate quality assurance and control program is urged during project construction to verify that the design plans and good construction practices are. followed. This is ' especially important for sites lying close to the major seismic sources. ' EARTH SYSTEMS SOUTHWEST November 22, 2005 16 File No.: 10405-01 ' 05-12-704 ' Section 6 LIMITATIONS AND ADDITIONAL SERVICES 6.1 Uniformity of Conditions and Limitations ' Our findings and recommendations in this report are based on select g p ed points of field ' exploration, laboratory testing, and our understanding of the proposed project. Furthermore, our findings and recommendations are based on the assumption that soil conditions do not vary significantly from those found at specific exploratory locations. Variations in soil or ' groundwater conditions could exist between and beyond the exploration points. The nature and extent of these variations may not become evident until construction. Variations in soil or groundwater may require additional studies, consultation, and possible revisions to our ' recommendations. Findings of this report are valid as of the issued date of the report. However, changes in ' conditions of a property can occur with passage of time, whether they are from natural processes or works of man, on this or adjoining properties. In addition, changes in applicable standards occur, whether they result from legislation or broadening of knowledge. Accordingly, findings of this report may be .invalidated wholly or partially by changes outside our control. Therefore, this report is subject to review and should not be relied upon after a period of one year. ' In the event that any changes in the nature, design, or location of structures are planned, the conclusions and recommendations contained in this report shall not be considered valid unless the changes are reviewed and the conclusions of this report are modified or verified in writing. ' This report is issued with the understanding that the owner or the owner's representative has the responsibility to bring the information and recommendations contained herein to the attention of ' the architect and engineers for the project so that they are incorporated into the plans and specifications for the project. The owner or the owner's representative also has the responsibility to verify that the general contractor and all subcontractors follow such recommendations. It is ' T 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. II EARTH SYSTEMS SOUTHWEST November 22, 2005 17 File No.: 10405-01 05-12-704 ' Although available through ESSW, the current scope of our services does not include an environmental assessment or an investigation for the presence or absence of wetlands, hazardous or toxic materials in the soil, surface water, groundwater, or air on, below, or adjacent to the subject property. 6.2 Additional Services ' This report is based on the assumption that an adequate program of client consultation, construction monitoring, and testing will be performed during the final design and construction ' phases to check compliance with these recommendations. Maintainir_g ESSW as the geotechnical consultant from beginning to end of the project will provide continuity of services. The geotechnical engineering firm providing tests and observations shall assume the responsibility of Geotechnical Engineer of Record. Construction monitoring and testing would be additional services provided by our firm. The costs of these services are not included in our present fee arrangements, but can be obtained from our office. The recommended review, tests, and observations include, but are not necessarily limited to, the following: ' • Consultation during the final design stages of the project. ' • A review of the building and grading plans to observe that recommendations of our report have been properly implemented into the design. • Observation and testing during site preparation, grading, and placemen-- of engineered fill as required by CBC Sections 1701 and 3317 or local grading ordinances. ' • Consultation as needed during construction. -000- Appendices as cited are attached and complete this report. 1 EARTH SYSTEMS SOUTHWEST November 22, 2005 REFERENCES ile No.: 10405-01 05-12-704 Abrahamson, N., and Shedlock, K., editors, 1997, Ground motion attenuLtion relationships: Seismological Research Letters, v. 68, no. 1, January 1997 special issue, 256 p. American Concrete Institute (ACI), 2004, ACI Manual of Concrete Practice, Paris 1 through 5. American Society of Civil Engineers (ASCE), 2003, Minimum Design Loads for Buildings and Other Structures, ASCE 7-02 California Department of Water Resources, 1964, Coachella Valley Investigation, Bulletin No. 108, 146 pp. California Geologic Survey (CGS), 1997, Guidelines for Evaluating and relitigating 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. Envicom Corporation and the County of Riverside Planning Department, 19'16, Seismic Safety and Safety General Plan Elements Technical Report, County of Riverside. Ferguson Engineering, Precise Grading Plan, Lot 16, Tract 2667, Sheets 1 & 2, nDt dated. Frankel, A.D., et al., 2002, Documentation for the 2002 Update of the National Seismic Hazard Maps, USGS Open -File Report 02-420. Hart, E.W., 1997, Fault -Rupture Hazard Zones in California: California Division of Mines and Geology Special Publication 42. ' International Code Council (ICC), 2002, California Building Code, 2001 Edition_ Jennings, CW, 1994, Fault Activity Map of California and Adjacent Areas: California Division of Mines and Geology, Geological Data Map No. 6, scale 1:750,000. Petersen, M.D., Bryant, W.A., Cramer, C.H., Cao, T., Reichle, M.S., Frankel, A.D., Leinkaemper, ' J.J., McCrory, P.A., and Schwarz, D.P., 1996, Probabilistic Seismic Hazard Assessment for the State of California: California Division of Mines and Geology Open -File Report 96-08. Proctor, R. J., 1968, Geology of the Desert Hot Springs - Upper Coachella Valley Area, California Division of Mines and Geology, DMG Special Report 94. ' 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. 1 EARTH SYSTEMS SOUTHWEST November 22, 2005 19 File No.: 10405-01 05-12-.704 Rogers, T.H., 1966, Geologic Map of California - Santa Ana Sheet, California Division of Mines and Geology Regional Map Series, scale 1:250,000. Structural Engineers Association of California (SEAOC), 1996, Recommended Lateral Force Requirements and Commentary. Tokimatsu, K, and Seed, H.B.; 1987, Evaluation of Settlements in Sands Due To Earthquake Shaking, ASCE, Journal of Geotechnical Engineering, Vol. 113, No. 8, August 1987. Wallace, R. E., 1990, The San Andreas Fault System, California: U.S. Geological Survey Professional Paper 1515, 283 p. 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., EARTH SYSTEMS SOUTHWEST 11 ' APPENDIX A Figure 1 — Site Location Map Figure 2 — Boring Location Map Table 1 — Fault Parameters Terms and Symbols used on Boring Logs ' Soil Classification System Logs of Borings Seismic Analysis Result ' EARTH SYSTEMS SOUTHWEST O O :;t CD N M M 7 I M M 0 0 0 t - M M 116°17'15"W 116°16'30"W 116°15'45"W 566000 567000 568000 569000 �.� 'AVENUE 1 .a '1 � r �'_. \ •. '/ L�� .. `li� ..-� -O+ :j ell •'1/ENU.E:� PatTt. C` _ , y2 49 1 MMES 1r1Ck�F- S� J/'�. T•�•� 3htrf!w♦ J.:.�� I � I I � \ �••1 J t� ty , ?ERr4i }rt l�Y t -e 3N olnZ 1, \ g , � r h.•�:,;._y.. 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J{ ,..:. fs •1. c i'tal!_ ri� liF.t.f i'r p R A �`�{1 •-r �• .. Y� " wie 1 Pr;rk"y J 1 Et /'. 1 '.1 F+4 a•.. >t? :. t A1Y i .s.co L ft v� `' s• e a it 'tir .. �Y'r t,t •r � .«� tft MDi1,1i �a�s`tt • D :v;p. A. �� {+iy • r�pp �J:�� HI'� � I ��YROkI��IA :,! �1�ei'At •� t !. Trailer Park ■ ka7::. ' K,. t .°. •- .-•1:, .aa'w•a' fj - ♦ Y�,T ♦• hxR♦-sM•�la4iauIt L'"'_ - I! ' a1♦ }i' k - 1a.. `..�, .\F•er '. .i N. BX Wf.'i j'• !• I .r�sw. et __ '. I "C � i' I2tlht', E � Czi15a(Y.: 'aaa B: ,IiYts�-.i�sy •••t w �. Y.le1•.R��11 D• 'Q �' t 1 :ss 3r•x• 0 gNUEli.re ws ,48 J:eat: p � li JL vrk all •. +. � _ .>j,rac it �" �WpJI-• - .. � 1 : iii+ - ..�'�' i+r ��sa - d c. W i.i Sr,s 1b9 • 1'J r I � � a:r�t•ra �; m . :. y a, J . j�'- 'Q N f ;tlFi"f.rtea . S` S VV rl - fY• 1 ��, Oai.�iTclw ra rablt' tt'Ir ' \. (( y _ _ i t\e - - J ••.Ayif •4tffte�•+T ax 3j i I,'�! :- �Y, �• - .. �• `� r,. A .1 - fwe •i t.i+r-� SYS} -x'� r f I� ` P '� �Jt r•\,D�'.=tMYatti••V IaiYrr-'�. 1Ne(1 i•rssrt•r49 sl :*I.. t 3;2• t. - f ��, •�.. L Arai]'.�"�*•i..k'%``.;fk.!:;�'j.l•. 566000 116017'15"W 567000 568000 116016'30"W 116°15'45"7Y • Figure 1• Site Location Map 46-461 Roadrunner Lane La Quinta, California O0 m' Earth System's Southwest 22/05 1 1 • File No.: 10405-01 569000 • 116016'27"W 567200' 567250 567300 567350 CD ?: tt _� G Ro�drunner.Lane » t 7 Roudel LanCD e o n`n 4,0 CD i 1 w ell O 'y.. ��.+.. t Lgy'+ t:J ii}?_j i.,.7+ • [L_•}T, rI O CD `n 567200 567250 567300 567350 ' 116016'27"W 1 0 30 60 120 180 24'1 300 Feet ' Figure 2 LEGEND Boring Location Map S Boring Location 46-461 Roadrunner Lane La Quinta, California 1 Site Boundary Earth Systems '0 Southwest 11/22/05 File No.: 10405-01 46-461 Roadrunner Lane, La Quinta, CA 10405-01 Table 1 Fault Parameters & neterministir Estimates nfMPan PPalr f_'rnnnd AerPlPratinn !P(_A\ Fault Name or Seismic Zone Distance from Site (nii) (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 5.0 8.0 SS A 7.7 24 220 199 0.46 San Andreas - Mission Crk. Branch 5.3 8.6 SS A 7.2 25 220 95 0.38 San Andreas - Banning Branch 5.3 8.6 SS A 7.2 10 220 98 0.38 Blue Cut 13.7 22.0 SS C 6.8 1 760 30 0.17 Burnt Mtn. 17.2 27.7 SS B 6.5 0.6 5000 21 0.12 San Jacinto (Hot Spgs - Buck Ridge) 17.6 28.3 SS C 6.5 .2 354 70 0.12 Eureka Peak 18.0 29.0 SS B 6.4 0.6 5000 19 0.11 San Jacinto -Anna 22.0 35.4 SS A 7.2 12 250 91 0.14 San Jacinto -Coyote Creek 22.3 35.9 SS B 6.8 4 175 41 0.11 Morongo 28.7 46.2 SS C 6.5 0.6 1170 23 0.07 Pinto Mountain 30.2 48.5 SS B 7.2 2.5 499 74 0.11 Emerson So. - Copper Mtn. 31.2 50.3 SS B 7.0 0.6 5000 54 0.09 Landers 32.2 51.9 SS B 7.3 0.6 5000 83 0.11 Pisgah -Bullion Mtn. -Mesquite Lk 33.2 53.5 SS B 7.3 0.6 5000 89 0.10 San Jacinto - Borrego 35.6 57.3 SS B 6.6 4 175 29 0.06 San Jacinto -San Jacinto Valley 37.0 59.5 SS B 6.9 12 83 43 0.07 North Frontal Fault Zone (East) 38.5 62.0 RV B 6.7 0.5 1727 27 0.08 Earthquake Valley 40.6 65.4 SS B 6.5 .2 351 20 0.05 Brawley Seismic Zone 41.2 66.3 SS B 6.4 25 24 42 0.05 Johnson Valley (Northern) 43.0 69.2 SS B 6.7 0.6 5000 35 0.06 Calico - Hidalgo 44.7 71.9 SS B 7.3 0.6 5000 95 0.08 Elsinore -Julian 44.7 72.0 SS A 7.1 5 340 76 0.07 Elsinore -Temecula 48.4 77.9 SS B 6.8 5 240 43 0.05 Lenwood-Lockhart-Old Woman Sprgs 48.9 78.7 SS B 7.5 0.6 5000 145 0.08 Elmore Ranch 49.4 79.5 SS B 6.6 1 225 29 0.05 North Frontal Fault Zone (West) 49.7 80.0 RV B 7.2 1 1314 50 0.08 Elsinore -Coyote Mountain 51.8 83.3 SS B 6.8 4 625 39 0.05 Superstition Mtn. (San Jacinto) 53.6 86.2 SS B 6.6 5 500 24 0.04 Superstition Hills (San Jacinto) 54.4 87.5 SS B 6.6 4 250 23 0.04 Helendale - S. Lockhardt 56.9 91.5 SS B 7.3 0.6 5000 97 0.06 San Jacinto -San Bernardino 59.1 95.1 SS B 6.7 12 100 36 0.04 Elsinore -Glen Ivy 61.9 99.6 SS B 6.8 5 340 36 0.04 iv oLes: 1. Jennings (1994) and California Geologic Survey (CGS) (2003) 2. CGS (2003), SS = Strike -Slip, RV = Reverse, DS = Dip Slip (normal), BT = Blind Thrust 3. 2001 CBC, where Type A faults: Mmax > 7 & slip rate >5 mm/yr & Type C faults: Mmax <6.5 & slip rate < 2 mm/yr 4. CGS (2003) 5. The estimates of the mean Site PGA are based on the following attenuation relationships: Average of: (1) 1997.Boore, Joyner & Fumal; (2)1997 Sadigh et al; (3) 1997 Campbell , (4) 1997 Abrahamson & Silva (mean plus sigma values are about 1.5 to 1.6 times higher) Based on Site Coordinates: 33.711 N Latitude, 116.274 W Longtude and Site Soil Type D EARTH SYSTEMS SOUTHWEST 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 DESCRIPTIVE SOIL CLASSIFICATION SOIL GRAIN SIZE U.S. STANDARD SIEVE 12" 3" 3/4" 4 10 40 200 GRAVEL SAND BOULDERS COBBLES COARSE FINE COARSE MEDIUM FINE S LT CLAY 305 76.2 19.1 4.76 2.00 0.42 n n74 n nng SOIL GRAIN SIZE IN MILLIMETERS RELATIVE DENSITY OF GRANULAR SOILS (GRAVELS, SANDS, AND NON -PLASTIC SILTS) Very Loose *N=0-4 RD=0-30 Easily push a 1/2 -inch reinforcing rod by hand Loose N=5-10 RD=30-50 Push a 1/2 -inch reinforcing rod by hand Medium Dense N=11-30 RD=50-70 Easily drive a 1/2 -inch reinforcing rod with hammer Dense N=31-50 RD=70-90 Drive a 1/2 -inch reinforcing rod 1 foot wife difficulty by a hammer Very Dense N>50 RD=90-100 Drive a 1/2 -inch reinforcing rod a few inches with hammer *N=Blows per foot in the Standard Penetration Test at 60% theoretical energy. For the 3 -inch diameter Modified California sampler, 140 -pound weight, multiply the blow count by 0.63 (about 2/3) to estimate N. If automatic hammer is used, multiply a factor of 1.3 to 1.5 to estimate N. RD=Relative Density (%). C=Undrained shear strength (cohesion). CONSISTENCY OF COHESIVE SOILS (CLAY OR CLAYEY SOILS) Very Soft *N=0-1 *C=0-250 psf Squeezes between fingers Soft N=2-4 C=250-500 psf Easily molded by finger pressure Medium Stiff N=5-8 C=500-1000 psf Molded by strong finger pressure Stiff N=9-15 C=1000-2000 psf Dented by strong finger pressure Very Stiff N=16-30 C=2000-4000 psf Dented slightly by finger pressure Hard N>30 C>4000 Dented slightly by a pencil point or thumonail MOISTURE DENSITY Moisture Condition: An observational term; dry, damp, moist, wet, saturated. Moisture Content: The weight of water in a sample divided by the weight of dry soil in the soil sarnple LOG KEY SYMBOLS expressed as a percentage. PLASTICITY Dry Density: The pounds of dry soil in a cubic foot. DESCRIPTION FIELD TEST MOISTURE CONDITION RELATIVE PROPORTIONS Dry .....................Absence of moisture, dusty, dry to the touch Trace ............. miror amount (<5%) Damp................Slight indication of moisture with/some ...... sig-iificant amount Moist.................Color change with short period of air exposure (granular soil) modifier/and ... suTiicient amount to The thread can barely be rolled. Below optimum moisture content (cohesive soil) infijence material behavior Wet....................High degree of saturation by visual and touch (granular soil) (Typically >30%) Modified California Sampler Above optimum moisture content (cohesive soil) The thread can be rerolled several times Saturated .......... Free surface water LOG KEY SYMBOLS PLASTICITY Bulk, Bag or Grab Sample DESCRIPTION FIELD TEST Nonplastic A 1/8 in. (3 -mm) thread cannot be rolled Standa®d Penetration at any moisture content. Split Spoon Sampler Low The thread can barely be rolled. (2° outs cle diameter) Medium The thread is easy to roll and not much time is required to reach the plastic limit. ' Modified California Sampler High The thread can be rerolled several times (3 outs de diameter) after reaching the plastic limit. No Recovery GROUNDWATER LEVEL Water Level (measured or after drilling) Terms and Symbols used on Boring I Water Level (during drilling) ll 1 i_l GRAPHIC LETTERSYMBOL MAJOR DIVISIONS SYMBOL TYPICAL DESCRIPTIONS Well -graded gravels, gravel -sand GW mixtures, little or no fines CLEAN rrrrrlr' GRAVELS GRAVEL AND :' :r:'!�� :'.• GP Poorly -graded gravels, gravel -sand GRAVELLY +r+'�+ + +--+:r+. mixtures. Little or no fines SOILS r•.r•.r,.r..r,.�..r.. GM S'Ity gravels, gravel -sand -silt COARSE More than 50% of GRAVELS ......:::::: mixtures GRAINED SOILS coarse fraction WITH FINES retained on No. 4 GC Clayey gravels, gravel -sand -clay sieve mixtures SW Well -graded sands, gravelly sands, SAND AND CLEAN SAND . . little or no fines SANDY SOILS Little or no fines):.. (.: SP Poorly -graded sands, gravelly More than 50% of sands, little or no fines material is larger than No. 200 sieve sizeSM Sity sands, sand -silt mixtures SAND WITH FINE More than 50% of (appreciable coarse fraction amount of fines) : passing No. 4 sieve SC Clayey sands, sand -clay mixtures Inorganic silts and very fine sands, ML rock four, silty low clayey fine sands or clayey silts with slight plasticity Inorganic clays of low to medium FINE-GRAINED LIQUID LIMIT LESS THAN 50 CL plasticity, gravelly clays, sandy SOILS clays, silty clays, lean clays OL i anic silts and organic silty Cg 9 clays of low plasticity SILTS AND Ir organic silty, micaceous, or CLAYS MH datomaceous fine sand or silty soils More than 50% of material is smaller LIQUID LIMIT CH Inorganic clays of high plasticity, than No. 200 GREATER fat clays sieve size THAN 50 ............ ............ Organic clays of medium to high ............ ............ OH plasticity, organic silts HIGHLY ORGANIC SOILS J'.Y.Y.YJ'J'J'J'Y.YJ' PT P Peat, humus, swam soils with yryyyyrrrrr high organic contents .rrrrrrrrrrr VARIOUS SOILS AND MAN MADE MATERIALS Fill Materials MAN MADE MATERIALS Asphalt and concrete Soil Classification System Earth Systems =� Southwest Earth Systems Southwest 79-811 B Country Club Drive, Bermuda Dunes, CA 92203 • Ynone(/b I).54.-I3zs5, Pax(touj Boring No: B-1 SP -SM Drilling Date: November: 1, 2005 Project Name: 46-461 Roadrunner Lane, La Quinta, CA Drilling Method: 8" Ho]ow Stem Auger, File Number: 10405-01 Drill Type: Cal Pac Mobile B61 w/Auto Hammer Boring Location: See Figure 2 Logged By: Dirk Wiggins v Sample Typew Penetration o 94 5 Description of Units Page I of 1 a Resistance U A g o y Note: The stratification lines shown represent the 5 Y q o approximate boundary between soil and/or rock types Graphic Trend A0. 0 (Blows/6") 6 medium dense, moist A U and the transition may be gradational. Blow Count Dry Density -5 - 10 - 15 -20 -25 -30 - 35 -40 -45 -50 - 55 -60 SP -SM SAND WITH SILT: pale yellowish brown, loose, moist, fine to medium grained 4,5,4 94 5 2,2,5 90 5 3,8,11 104 6 medium dense, moist 6,9,15 105 6 7,12,20 111 8 dense Total Depth 21.5 feet No Groundwater Encountered Backfilled with cuttings 01 1 1 1 1 1 1 1 1 1 1 1 1 1 Earth Systems 0Southwest 79-811 B Country Club Drive, Bermuda Dunes, CA 92203 -5 - 10 - 15 - 20 - 25 - 30 - 35 -40 -45 - 50 - 55 - 60 rnone t/tv) 34�-166, rax (Iou) Boring No: B-2 SP -SM SAND WITH SILT: pale yellowish brown, medium Drilling Date: November 1, 2005 Project Name: 46-461 Roadrunner Lane, La Quinta, CA Drilling Method: 8" Hollow Stem Auger File Number: 10405-01 dense, moist, fine to medium grained Drill Type: Cal Pac Mobile B61 w/Auto Hammer Boring Location: See Figure 2 Logged By: Dirk Wiggins Sample Type Penetration °: Description of Units Page 1 of 1 o A Resistance 91 4 A a o Y Note: The stratification lines shown represent the x 4,6,10 q o approximate boundary between soil and/or rock types Graphic Trend A (Blows/6") q U and the transition may be gradational. Blow Count Dry Density -5 - 10 - 15 - 20 - 25 - 30 - 35 -40 -45 - 50 - 55 - 60 SP -SM SAND WITH SILT: pale yellowish brown, medium dense, moist, fine to medium grained 5,7,8 97 5 2,3,4 91 4 loose, damp 4,6,10 97 9 medium dense, mosit SM SILTY SAND: dark yellowish brown, medium 4,5,7 93 12 dense, damp to moist, fine to medium grained SP -SM SAND WITH SILT: pale yellowish brown, medium 5,8,15 105 7 dense, moist, fine to medium grained 6,9,12 6,11,14 moderate yellowish brown Total Depth 31.5 feet No Groundwater Encountered Backfilled with cuttings 0t 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Earth Systems Southwest 79-811B Country Club Drive, Bermuda Dunes, CA 92203 rnone titin s4.)-uaa, rax tiov� sv�-is u Boring No: B-3 Drilling Date: November 1, 2005 Project Name: 46-461 Roadrunner Lane, La Quinta, CA Drilling Method: 8" Ho_low Stem Auger File Number: 10405-01 Drill Type: Cal Pac Mobile B61 w/Auto Hammer Boring Location: See Figure 2 Logged By: Dirk Wiggi:as Sample o Type Penetration N °-''.�. D@SCrlpilOn Of Units Page 1 of 1 o `n r 8 " y v Resistance t q o • 2 Note: The stratification lines shown represent Gee Ac' q o approximate boundary between soil and/or rock types Graphic Trend N(Blows/6") q U and the transition may be gradational. Blow Count Dry Density -5 - 10 -20 -25 - 30 - 35 -40 -45 - 50 - 55 -60 7,10,11 2,3,4 2,4,5 SP -SM 100 90 84 6 7 ]0 SAND WITH SILT: moderate yellowisl- brown, medium dense, damp, fine to medium grained, trace of mica loose dark yellowish brown, loose, with lenses of silty sand, Poor Recovery Total Depth 14 feet No Groundwater Encountered Backfilled with cuttings I= 1 APPENDIX B Laboratory Test Results EARTH SYSTEMS SOUTHWEST File No.: 10405-01 Nov.mber 22, 2005 Lab No.: 05-0687 UNIT DENSITIES AND MOISTURE CONTENT ASTM D2937 & D2216 Job Name: 46-461 Roadrunner Lane, La Quinta 1 ' Unit Moisture USCS Sample Depth Dry Content Group Location (feet) Density ( cf) (%) Symbol BI 2.5 94 5 SP -SM BI 5 90 5 SP -SM BI 10 104 6 SP -SM BI 15 105 6 SP -SM ' BI 20 111 8. SP -SM B2 2.5 97 5 SP -S\4 ' B2 5 91 4 SP -SM B2 10 97 9 SP -SM B2 .15 93 12 Sm ' B2 20 105 7 SP -SM B3 2.5 100 6 SP -SM ' B3 7.5 90 7 SP -SM B3 12.5 84 10 SP -CM 1 EARTH SYSTEMS SOUTHWEST File No.: 10405-01 Job Name: 46-461 Roadrunner Lane, La Quinta Lab Number: 05-0687 AMOUNT PASSING NO. 200 SIEVE ff-M 5 5 SP -SM EARTH SYSTEMS SOUTHWEST November 22, 2005 ASTM D 1140 Fines USCS Sample Depth Content Group Location (feet) N Symbol ff-M 5 5 SP -SM EARTH SYSTEMS SOUTHWEST November 22, 2005 ASTM D 1140 1 1" 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 UP ill�ilill IN IN III HIM IN 01111111111111111 Mill ilillimilill III111 MIN lllilloililill 1111111 11110 ililillimililill I oil III E liiiilmiiiiii IN mill IN iiiiiiimiiiii I NEI 1 11 III 111EIlI11111 100 10 1 0.1 0.01 0.001 Particle Size ( mm) EARTH SYSTEMS SOUTHWEST . File No.: 10405-01 November 22, 2005. Lab No.: 05-0687 PARTICLE SIZE ANALYSIS ASTM D-422 Job Name: 46-461 Roadrunner Lane, La Quinta Sample ID: B2 @ 1-4 Feet Description: Sand F (SP -SM) 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: 90 #50 93 % Silt: 4 #100 50 % Clay (3 micron): 6 #200 10 (Clay content by short hydrometer method) 1 UP ill�ilill IN IN III HIM IN 01111111111111111 Mill ilillimilill III111 MIN lllilloililill 1111111 11110 ililillimililill I oil III E liiiilmiiiiii IN mill IN iiiiiiimiiiii I NEI 1 11 III 111EIlI11111 100 10 1 0.1 0.01 0.001 Particle Size ( mm) EARTH SYSTEMS SOUTHWEST File No.: 10405-01 November 22, 2005 Lab No.: 05-0687 CONSOLIDATION TEST ASTM E 2435 & D 5333 46-461 Roadrunner Lane, La Quinta Initial Dry Density: 86.4 pcf B-1 @ 5 feet Initial Moisture, %: 5.4% Sand w/Silt (SP -SM) Specific Gravity (assumed): 2.67 Ring Sample Initial Void Ratio: 0.929 Hydrocollapse: 0.7% @ 2.0 ksf 2 1- 0 -1 - 2 y ao -3 a� -4 a� oc c� -5 4 U -6 ej i.. 61 -7 a -8 -9 -10 -11 -12 0.1 %Change in Height vs Normal Presssure Diagram —^@—Before Saturation —^y—Hydrocollapse ® After Saturation — 0 Rebound 1.0 Vertical Effective Stress, ksf EARTH SYSTEMS SOUTHWEST 10.0 1 1 1 1 1 1 1 1 1 1 1 File No.: 10405-01 Lab No.: 05-0687 November 22, 2005 CONSOLIDATION TEST ASTM D 2435 & D 5333 46-461 Roadrunner Lane, La Quinta B2 @ 15 Feet Silty Sand (SM) Ring Sample 2 1 0 1 2 °ou -3 x -4 a� on q R -5 U b -6 d v -7 a -8 -9 -10 -11 -12 0.1 Initial Dry Density: 88.2 pcf Initial Moisture, %: 11.6% Specific Gravity (assumed): 2.67 Initial Void Ratio: 0.889 Hydrocollapse: 0.6% @ 2.0 ksf % Change in Height vs Normal Presssure Diagram —Before Saturation —°°Hydrocollapse ® After Saturation ---*—Rebound 1.0 Vertical Effective Stress, ksf EARTH SYSTEMS SOUTHWEST e n 10.0 1 File No.: 10405-01 November 22, 2005 Lab No.: 05-0687 MAXIMUM DENSITY / OPTIMUM MOISTURE ASTM D 1537-91 (Modified) Job Name: 46-461 Roadrunner Lane, La Quinta Proc•-,dure Used: A Sample ID: 1 Preparation Method: Moist Location: B2 @ 1-4 Feet Rammer Type: Mechanical Description: Yellowish Brown Sand w/Silt (SP- Lab Number: 05-0687 SM) Sieve Size % Retained Maximum Density: 103 pcf 3/4" 0.0 Optimum Moisture: 12% 3/8" 0.5 #4 0.5 140 135 130 125 110 105 100 0 5 10 15 20 25 30 35 Moisture Content, percent EARTH SYSTEMS SOUTHWEST 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 File No.: 10405-01 Nov -,tuber 22, 2005 Lab No.: 05-0687 Degree of Corrosivity Soluble SOIL CHEMICAL ANALYSES Low Sulfates 1000 - 2000 mg/Kg (ppm) [0.1-0.2%] Modera-:e Job Name: 46-461 Roadrunner Lane, La Quinta 2000 - 20,000 mg/Kg (ppm) [0.2-2.0%] Severe Job No.: 10405-01 > 20,000 m m >2.0% Very Severe Sample ID: B2 1-1000 ohm -cm Very Severe Sample Depth, feet: 1-4' DF RL Sulfate, mg/Kg (ppm): - 3 1 0.50 Chloride, mg/Kg (ppm): 19 1 0.20 pH, (pH Units): 8.15 1 0.41 Resistivity, (ohm -cm): 5,200 =v/A N/A Conductivity, (µmhos -cm): 1 2.00 Note: Tests performed by Subcontract Laboratory: Surabian AG Laboratory DF: Dilution Factor 105 Tesori Drive RL: Repenting Limit Palm Desert, California 92211 Tel: (760) 200-4498 General Guidelines for Soil Corrosivity Chemical Agent Amount in Soil Degree of Corrosivity Soluble 0 -1000 mg/Kg (ppm) [ 0-,1%] Low Sulfates 1000 - 2000 mg/Kg (ppm) [0.1-0.2%] Modera-:e 2000 - 20,000 mg/Kg (ppm) [0.2-2.0%] Severe > 20,000 m m >2.0% Very Severe Resistivity 1-1000 ohm -cm Very Severe 1000-2000 ohm -cm Severe 2000-10,000 ohm -cm Moderate 10,000+ ohm -cm Low EARTH SYSTEMS SOUTHWEST