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08-0946 (RC) Geotechnical Engineering ReportPYRAMID PROJECT MANAGEMENT, LLC ONE POST OFFICE SQUARE, SUITE 3100 BOSTON, MASSACHUSETTS. 02109 GEOTECHNICAL ENGINEERING REPORT PROPOSED PGA WEST STADIUM CLUBHOUSE REMODEL 56-150 PGA BOULEVARD LA QUINTA, CALIFORNIA May 23, 2008 CITY OF LA QUINT'A BUILDING & SAFETY DEPT. APPROVED FOR CONSTRUCTION DATE -1.k1* BY 4• •E&7 "1117101 i © 2008 Earth Systems Southwest Unauthorized use or copying of this document is strictly prohibited without the express written consent of Earth Systems Southwest. File No.: 11446-01 Doc. No.: 08-05-782 MAY 3 0-1 008 I U Earth Systems 11 Southwest 79-811B Country Club Drive Bermuda Dunes, CA 92203 (760)345-1588 (800)924-7015 FAX (760) 345-7315 May 23, 2008 Pyramid Project Management, LLC One Post Office Square, Suite 3100 Boston, Massachusetts 02109 Attention: Mr. William Tom Project: Proposed PGA West Stadium Clubhouse Remodel 56-150 PGA Boulevard La Quinta, California Subject: Geotechnical Engineering Report File No.: 11446-01 Doc. No.: 08-05-782 We take pleasure in presenting this geotechnical engineering report prepared for the proposed remodel project of the PGA West Stadium Clubhouse located at 56-150 PGA Boulevard in the City of La Quinta; Riverside County, 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. 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 April 18, 2008. Other services that may be required, such as plan review and grading observation, are additional services and will be billed according to our Fee Schedule in effect at the time services are provided. Unless requested in writing, the client is responsible for distributing this report to the appropriate governing agency or other members of the design team. We appreciate the opportunity to provide our professional services. Please contact our office if there are any questions or comments concerning this report or its recommendations. Respectfully submitted, . EARTH SYSTE S SOUTHWEST Reviewed by, Karl A. Harmon QPOFE$SON Craig S. Hill CE 67812i�;�. Q� p` HAR,ygl� E 38234 SER/kah/csh/ajf Na67812 Z Distribution: 6/Pyramid Project Man ent, LLC a . 1/RC File 2/BD File„_ 0 j \ CE 38234 / EXP 3/3IW- 1 TABLE OF CONTENTS Page EXECUTIVE SUMMARY Soil Conditions...................................................................................................4 Section 1 INTRODUCTION............................................................................................1 Groundwater......................................................................................................4 1.1 Project Description.............................................................................................1 Geologic Setting.................................................................................................4 1.2 Site Description.................................................................................................. l 1.3 Purpose and Scope of Services..........................................................................1 3.4.1 Seismic Hazards.....................................................................................5 Section 2 METHODS OF INVESTIGATION...............................................................3 3.4.2 Secondary Hazards.................................................................................6 2.1 Field Exploration...............................................................................................3 3.4.3 Site Acceleration and Seismic Coefficients...........................................6 2.2 Laboratory Testing.............................................................................................3 CONCLUSIONS..............................................................................................8 Section 3 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...........................................6 Section 4 CONCLUSIONS..............................................................................................8 Section 5 RECOMMENDATIONS.................................................................................9 SITE DEVELOPMENT AND GRADING...................................................................9 5.1 Site Development — Grading..............................................................................9 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...................................................................................15 Section 6 LIMITATIONS AND ADDITIONAL SERVICES....................................16 6.1 Uniformity of Conditions and Limitations......................................................16 6.2 Additional Services..........................................................................................17 REFERENCES...........................................................................................................18 APPENDIX A Figure 1 — Site Location Map Figure 2 — Boring Location Map Table 1 — Fault Parameters Terms and Symbols used on Boring Logs Soil Classification System Logs of Borings APPENDIX B Laboratory Test Results EARTH SYSTEMS SOUTHWEST 11 EXECUTIVE SUMMARY Earth Systems Southwest has prepared this executive summary solely to provide a general overview of the report. The report itself should be relied upon for information about the findings, conclusions, recommendations, and other concerns. The site is located at 56-150 PGA Boulevard in the City of La Quinta, Riverside County, California. The proposed development will include a new 38' to 7" long by 8' to 12' high retaining wall at the southeast comer of the existing clubhouse, a second 57' to 10" long by 8' to 12' high retaining wall at the south end of the existing clubhouse, and a new veranda/patio arrayed along a portion of the east facade of the existing clubhouse. We understand that the proposed retaining structures will include both restrained and cantilevered walls, constructed of reinforced concrete and masonry supported with shallow foundations. 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 demolition of existing structures, clearing and grubbing of vegetation, site grading, building pad preparation, underground utility installation, street and parking lot construction, and concrete driveway and sidewalks placement. Based on the non-uniform nature and hydrocollapse potential of the near surface soils, remedial site grading is recommended to provide uniform support for the foundations. ✓Laboratory testing of the site soils indicate low levels of sulfate and chloride. ion content, therefore normal concrete mixes may be used. However, indications are that the onsite soils exhibit moderate resistivity resulting in a severe corrosion potential for buried metal pipes. Underground utilities and buried metal pipes will require corrosion protection from the surrounding soil. We consider the most significant geologic hazard to the project to be the potential for moderate to severe seismic shaking that is likely to occur during the design life of the proposed structures. The project site is located in the highly seismic Southern California region within the influence of several fault systems that are considered to be active or potentially active. Structures should be designed in accordance with the values and parameters given within the 2007 California Building Code (CBC) and ASCE 7-05. The seismic design parameters are presented in the following table and within the report. EARTH SYSTEMS SOUTHWEST SUMMARY OF RECOMMENDATIONS : Design Item �� Reeommen~ded k 8 { a r Y%, F��J rParamet�er�k PA Foundations Refereffi7ceLS.1*',,�c'tion Allowable Bearing Pressure Continuous wall footings Pad Column footings 1,500 psf/ 2,000 psf� 5.4 Foundation Type Spread Footing 5.4 Bearing Materials Engineered fill i Allowable Passive Pressure 300 psf ' 5.4 Active Pressure 35 pcf ' 5.6 At -rest Pressure 55 Pcf ' 5.6 Allowable Coefficient of Friction 0.30 5.4 Soil Expansion Potential Very low EI < 20 3.1 Geologic and Seismic Hazards Liquefaction Potential Low! 3.4.2 Significant Fault and Magnitude San Andreas, M7.7 3.4.1 Fault Type and Distance A, 7.8 km 3.4.1 Seismic Design Category D 5.8 Site Class D 5.8 Maximum Considered Earthquake CE Short Period Spectral Response, SS 1.50 g 5.8 Second Spectral Response, S1 0.60 g 5.8 Site Coefficient, Fa 1.00 5.8 Site Coefficient, F„ 1.50 5.8 Slabs Building Floor Slabs On engineered fill 5.5 Modulus of Subgrade Reaction 200, ci 5.5 Existing Site Conditions Existing Fill N/A Soil Corrosivity low sulfates low chlorides Severe resistivity 5.7 Groundwater Depth Presently > 60 feet, Historic z 50 feet 3.2 Estimated Fill and Cut excludes over -excavation Fill —12 feet Cut < 5 feet 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 May 23, 2008 GEOTECHNICAL ENGINEERING REPORT PROPOSED PGA WEST STADIUM CLUBHOUSE REMODEL 56-150 PGA BOULEVARD LA QUINTA, CALIFORNIA Section 1 INTRODUCTION 1.1 Project Description File No.: 11446-01 Doc. No.: 08-05-782 This geotechnical engineering report has been prepared for the proposed remodeling project of the PGA West Stadium Clubhouse within The Club at PGA West at 56-150 PGA Boulevard in the City of La Quinta, Riverside County, California.. The proposed development will include a new 38' to 7" long by 8' to 12' high retaining wall at the southeast comer of the existing clubhouse, a second 57' to 10" long by 8' to 12' high retaining wall at the south end of the existing clubhouse, and a new veranda/patio arrayed along a portion of the east facade of the existing clubhouse. We understand that the proposed retaining structures will include both restrained and cantilevered walls, constructed of reinforced concrete and masonry supported with shallow foundations. Site development will include demolition of existing structures, clearing and grubbing of vegetation, site grading, building pad preparation, underground utility installation, street and parking lot construction, and concrete driveway and sidewalks placement. Based on existing site topography and ground conditions, site grading is expected to consist of limited cuts and fills to obtain design grades (excluding over -excavation). We used maximum column loads of 30 kips and a maximum wall loading of 2.0 kips per linear foot as a basis for the foundation recommendations. Loading was provided by the project structural engineer. 1.2 Site Description The proposed remodeling project and additions will be constructed at the site of the existing PGA West Stadium Clubhouse. The project site presently consists of the clubhouse with associated surrounding landscape vegetation and hardscapes. The site location is shown on Figure 1 in Appendix A. There are underground utilities near and within the proposed building area. These utility lines include, but are not limited to, domestic water, natural gas, electric, sewer, telephone, cable, and irrigation lines. 1.3 Purpose and Scope of Services 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 services included the following: EARTH SYSTEMS SOUTHWEST May 23, 2008 2 File No.: 11446-01 Doc. No.: 08-05-782 ➢ A general reconnaissance of the site. ➢ Shallow subsurface exploration by drilling three exploratory borings to depths ranging from about 21.5 to 51.5 feet below existing grade. ➢ Laboratory testing of selected soil samples obtained from the exploratory borings. ➢ A review of selected published technical literature pertaining to the site and previous geotechnical reports prepared by ESSW for other sites within The Club at PGA West. ➢ An engineering analysis and evaluation of the acquired data from the exploration and testing programs. ➢ A summary of our fmdings 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: ➢ A corrosive study to determine cathodic protection of concrete or buried pipes. ➢ An environmental assessment. ➢ An investigation for the presence or absence of wetlands, hazardous or toxic materials in the soil, surface water, groundwater, or air on, below, or adjacent to the subject property. The client did not direct ESSW to provide any service to investigate or detect the presence of 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 the amplification of the same. Client acknowledges that mold is ubiquitous to the environment, with mold amplification occurring when building materials are impacted by moisture. 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 not be held responsible for the occurrence or recurrence of mold amplification. EARTH SYSTEMS SOUTHWEST May 23, 2008 3 File No.: 11446-01 Doc. No.: 08-05-782 Section 2 METHODS OF INVESTIGATION 2.1 Field Exploration Three exploratory borings were drilled to depths ranging from about 21.5 to 51.5 feet below the existing ground surface to observe the soil profile and to obtain samples for laboratory testing. The borings were drilled on April 25, 2008 using 8 -inch outside diameter hollow -stem augers, powered by a Simco 2800 truck -mounted drilling rig. The boring 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 automatic hammer, dropping 30 inches in general accordance with ASTM D 1586. Recovered soil samples were sealed in containers and returned to the laboratory. Bulk samples were also obtained from auger cuttings, representing a mixture of soils encountered at the depths noted. The final logs of the borings represent our interpretation of the contents of the field logs and the results of laboratory testing performed on the samples obtained during the subsurface exploration. The final logs are included in Appendix A of this report. The stratification lines represent the approximate boundaries between soil types, although the transitions may be gradational. 2.2 Laboratory Testing Samples were reviewed along with field logs to select those that would be analyzed further. Those selected for laboratory testing include. soils that would be exposed and used during grading and those deemed to be within the influence of the proposed structure. Test results are presented in graphic and tabular form in Appendix B of this report. The tests were conducted in general accordance with the procedures of the American Society for Testing and Materials (ASTM) or other standardized methods as referenced below. Our testing program consisted of the following: ➢ In-situ Moisture Content and Unit Dry Weight for the ring samples. ➢ Maximum density tests to evaluate the moisture -density relationship of typical soils encountered. ➢ Particle Size Analysis to classify and evaluate soil composition. The gradation characteristics of selected samples were made by hydrometer and sieve analysis procedures. ➢ Consolidation (Collapse Potential) to evaluate the compressibility and hydroconsolidation (collapse) potential of the soil. ➢ Chemical Analyses (Soluble Sulfates and Chlorides, pH, and Electrical Resistivity) to evaluate the potential adverse effects of the soil on concrete and steel. EARTH SYSTEMS SOUTHWEST May 23, 2008 4 File No.: 11446-01 Doc. No.: 08-05-782 Section 3 DISCUSSION 3.1 Soil Conditions The field exploration indicates that site soils consist predominately of Silty Sand with interbedded lenses and layers Sand, Silt and Clay (Unified Soils Classification System symbols of SM, SP -SM, ML, and CL). The boring logs provided in Appendix A include more detailed descriptions of the soils encountered. The near surface soils are visually classified to be in the very low expansion (EI < 20). Site soils are classified as Type C in accordance with Cal0SHA. In and climatic regions, granular soils may have a potential to collapse upon wetting. Collapse (hydroconsolidation) may occur when the soluble cements (carbonates) in the soil matrix dissolve, causing the soil to densify from its loose configuration from deposition. Consolidation testing indicates 0.1 to 0.6% collapse upon inundation and collapse is therefore considered a slight to moderate site risk. The hydroconsolidation potential is commonly mitigated by recompaction of a zone beneath building pads. 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 60 to 80 feet based on 1986 water well data obtained from the Coachella Valley Water District and ESSW's knowledge of the area. 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 however groundwater should not be a factor in design or construction at this site. 3.3 Geologic Setting Regional Geology: The site lies within the Coachella Valley, a part of the Colorado Desert geomorphic province. A significant feature within the Colorado Desert geomorphic province is the Salton Trough. The Salton Trough is a large northwest -trending structural depression that extends approximately 180 miles from the San Gorgonio Pass to the Gulf of California. Much of this depression in the area of the Salton Sea is below sea level. The Coachella Valley forms the northerly part of the Salton Trough. The Coachella Valley contains a thick sequence of Miocene to Holocene sedimentary deposits. Mountains surrounding the Coachella Valley include the Little San Bernardino Mountains on the northeast, foothills of the San Bernardino Mountains on the northwest, and the San Jacinto and Santa Rosa Mountains on the southwest. These mountains expose primarily Precambrian metamorphic and Mesozoic granitic rocks. The San Andreas fault zone within the Coachella Valley consists of the Garnet 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 at the base of the Santa Rosa Mountains approximately 6 miles west of the Whitewater River channel and approximately 10 feet below mean sea level in the western 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. EARTH SYSTEMS SOUTHWEST May 23, 2008 3.4 Geologic Hazards File No.: 11446-01 Doc. No.: 08-05-782 Geologic hazards that may affect the region include seismic hazards (ground shaking,surface fault rupture, soil liquefaction, and other secondary earthquake -related hazards), slope instability, flooding, ground subsidence, and erosion. A discussion follows on the specific hazards to this site.. 3.4.1 Seismic Hazards Seismic Sources: Several active faults or seismic zones lie within 62 miles (100 kilometers) of the project site as shown on Table 1 in Appendix A. The primary seismic hazard to the site is strong ground shaking from earthquakes along the San Andreas and San Jacinto faults. The Maximum Magnitude Earthquake (Mmax) listed is from published geologic information available for each fault (Cao et al., CGS, 2003). The Mmax corresponds to the maximum earthquake believed to be tectonically possible. Surface Fault Rupture: The project site does not lie within a currently delineated State of California, Alquist-Priolo Earthquake Fault Zone (Hart, 1997). Well -delineated fault lines cross through this region as shown on California Geological Survey (CGS) maps (Jennings, 1994); however, no active faults are mapped in the immediate vicinity of the site. Therefore, active fault rupture is unlikely to occur at the project. site. While fault rupture would most likely occur along previously established fault traces, future fault rupture could occur at other locations. Historic Seismicity: Six historic seismic events (5.9 M or greater) have significantly affected the Coachella Valley in the last 100 years. They are as follows: • Desert Hot Springs Earthquake — On December 4, 1948, a magnitude 6.5 ML (6.0 MW) earthquake occurred east of Desert Hot Springs. This event was strongly felt in the Coachella Valley. • 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 Coachella Valley and caused structural damage, as well as injuries. • Joshua Tree Earthquake — On April 22, 1992, a magnitude 6.1 ML (6.1Mw) earthquake occurred in the mountains 9 miles east of Desert Hot Springs. Structural damage and minor injuries occurred in the Coachella Valley area as a result of this earthquake. • Landers and Big Bear Earthquakes — Early on June 28, 1992, a magnitude 7.5 Ms (7.3Mw) earthquake occurred near Landers, the largest seismic event in Southern California for 40 years. Surface rupture occurred just south of the town of Yucca Valley and extended some 43 miles toward Barstow. About three hours later, a magnitude 6.6 Ms (6.4Mw) earthquake occurred near Big Bear Lake. No significant structural damage from these earthquakes was reported in the Coachella Valley. • Hector Mine Earthquake — On October 16, 1999, a magnitude 7.1Mw earthquake occurred on the Lavic Lake and Bullion Mountain faults north of Twentynine Palms. While this event was widely felt, no significant structural damage has been reported in the Coachella Valley. Seismic Risk: While accurate earthquake predictions are not possible, various agencies have conducted statistical risk analyses. In 2002, the California Geological Survey (CGS) and the United States Geological Survey (USGS) completed the latest generation of probabilistic seismic hazard maps. We have used these maps in our evaluation of the seismic risk at the site. The Working Group of California Earthquake Probabilities (WGCEP, 1995) estimated a 22% EARTH SYSTEMS SOUTHWEST May 23, 2008 6 File No.: 11446-01 Doc. No.: 08-05-782 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 that is about 7.8 km from the site and is considered as Fault Type A (CGS). 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 of any part of the San Andreas fault. The last rupture occurred about 1690 AD, based on dating by the USGS near Indio (WGCEP, 1995). This segment has also ruptured on about 1020, 1300, and 1450 AD, with an average recurrence interval of about 220 years. The San Andreas fault may rupture in multiple segments, producing a higher magnitude earthquake. Recent paleoseismic studies suggest that the San Bernardino Mountain Segment to the north and the Coachella Segment may have ruptured together in 1450 and 1690 AD (WGCEP, 1995). 3.4.2 Secondary Hazards Secondary seismic hazards related to ground shaking include soil liquefaction, ground subsidence, tsunamis, and seiches. The site is far inland, so the hazard from tsunamis is non- existent. At the present time, no water storage reservoirs are located in the immediate vicinity of the site. Therefore, hazards from seiches are considered negligible at this time. Soil Liquefaction: Liquefaction is the loss of soil strength from sudden shock (usually earthquake shaking), causing the soil to become a fluid mass. In general, for the effects of liquefaction to be manifested at the surface, groundwater levels must be within 50 feet of the 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 low because the depth of groundwater beneath the site exceeds 50 feet. No free groundwater was encountered in our exploratory borings. In addition, the project lies in a zone designated by Riverside County for high susceptibility sediments, but intermediate groundwater depths (50 to 100 feet) resulting in low liquefaction potential. Ground Subsidence: The potential for seismically induced ground subsidence is considered to be low at the site. Dry sands tend to settle and densify when subjected to strong earthquake shaking. The amount of subsidence is dependent on relative density of the soil, ground motion, and earthquake duration. Uncompacted fill areas may be susceptible to seismically induced settlement. Slope Instability: The site is relatively flat. Therefore, potential hazards from slope instability, landslides, or debris flows are considered negligible. 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) EARTH SYSTEMS SOUTHWEST May 23, 2008 7 File No.: 11446-01 Doc. No.: 08-05-782 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 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/data. Estimate of PGA from 2002 CGS/USGS Probabilistic Seismic Hazard Maps/Data Equivalent Return Risk Period (years) PGA (g) t 10% exceedance in 50 years 475 0.48 Notes: I Based on Site Class B/C and soil amplification factor of 1.0 for Site Class D. 2007 CBC Seismic Coefficients: The California Building Code (CBC) seismic design parameters criteria are based on a Design Earthquake that has an earthquake ground motion 2/3 of the lesser of 2% probability of occurrence in 50 years or 150% of mean deterministic limit. 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 2007 California Building Code are provided in Section 5.8 of this report. Seismic Hazard Zones: The site lies in a moderate liquefaction potential zone designated by the 2003 Riverside County Integrated Project because of intermediate groundwater (50-100 feet), and high susceptibility sediments. This portion of Riverside County has not been mapped by the California Seismic Hazard Mapping Act (Ca. PRC 2690 to 2699). EARTH SYSTEMS SOUTHWEST May 23, 2008 Section 4 CONCLUSIONS File No.: 11446-01 Doc. No.: 08-05-782 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 underlying geologic condition for seismic design is Site Class D. The site is about 7.8 km from a Type A seismic source as defined in the California Geological Survey. A qualified professional should design any permanent structure constructed on the site. The minimum seismic design should comply, with the 2007 edition of the California Building Code. ➢ Ground subsidence from seismic events or hydroconsolidation is a potential hazard in the Coachella Valley area. Adherence to the grading and structural recommendations in this report should reduce potential settlement problems from seismic forces, heavy rainfall or irrigation, flooding, and the weight of the intended structures. ➢ The soils are susceptible to wind and water erosion. Preventative measures to reduce seasonal flooding and erosion should be incorporated into site grading plans. Dust control should also be implemented during construction. Site grading should be in strict compliance with the requirements of the South Coast Air Quality Management District (SCAQMD). ➢ Other geologic hazards, including fault rupture, liquefaction, seismically induced flooding, and landslides, are considered low or negligible on this site. ➢ The upper soils were found to be relatively loose to medium dense and are unsuitable in their present condition to support structures, fill, and hardscape. The soils within the building and structural areas will require moisture conditioning, over -excavation, and recompaction to improve bearing capacity and reduce the potential for differential settlement from static loading. Soils can be readily cut by normal grading equipment. EARTH SYSTEMS SOUTHWEST May 23, 2008 9 File No.: 11446-01 Doc. No.: 08-05-782 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 landscape 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 demolition and 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). Footing Subgrade Preparation: Because of the relatively non-uniform and under -compacted nature of the site soils, we recommend recompaction of subgrade soils in the proposed building areas. The existing surface soils within the building pad and foundation areas should be over - excavated to a minimum of 3 feet below existing grade or a minimum of 2 feet below the footing level (whichever is lower). Existing adjacent structures must be protected in place during over - excavation and footing subgrade preparations. Work may require piecemeal preparation methods such as "s.lot-cuts" or "checker -boarding" techniques during the remedial grading along existing structures. Where possible, 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 one foot. Auxiliary Structures Subgrade Preparation: Auxiliary structures such as garden walls should have the foundation subgrade prepared similar to the building pad recommendations given above. The lateral extent of the over -excavation needs to extend only 2 feet beyond the face of the footing. Subgrade Preparation: In areas to receive fill, pavements, or hardscape, the subgrade should be scarified, moisture conditioned, and compacted to at least 90% relative compaction (ASTM D 1557) for a depth of one -foot below finished subgrades or one foot below the bottom of the foundation, whichever is deeper. Compaction should be verified by testing. Engineered Fill Soils: The native soil is suitable for use as engineered fill and utility trench backfill, provided it is free of significant organic or deleterious matter. The native soil should be placed in maximum 8 -inch lifts (loose) and compacted to at least 90% relative compaction (ASTM D 1557) near its optimum moisture content. Compaction should be verified by testing. EARTH SYSTEMS SOUTHWEST May 23, 2008 10 File No.: 11446-01 Doc. No.: 08-05-782 .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 20 percent for the upper excavated or scarified site soils. This estimate is based on compactive effort to achieve an average relative compaction of about 92% and may vary with contractor methods. Subsidence is estimated to range from 0.1 to 0.2 feet. Losses from site clearing and removal of existing site improvements may affect earthwork quantity calculations and should be considered. Site Drainage: Positive drainage should be maintained away from the structures (5% for 5 feet minimum) to prevent ponding and subsequent saturation of the foundation soils. Gutters and downspouts should be considered as a means to convey water away from foundations if adequate drainage is not provided. Drainage should be maintained for paved areas. Water should not pond on or near paved areas. 5.2 Excavations and Utility Trenches Excavations should be made in accordance with CalOSHA requirements. Our site exploration and knowledge of the general area indicates there is a potential for caving of site excavations (utilities, footings, etc.). Excavations within sandy soil should be kept moist, but not saturated, to reduce the potential of caving or sloughing. Where excavations over 4 feet deep are planned, lateral bracing or appropriate cut slopes of 1.5:1 (horizontal:vertical) should be provided. No surcharge loads from stockpiled soils or construction materials should be allowed within a horizontal distance measured from the top of the excavation slope and equal to the depth of the excavation. Utility Trenches: Backfill of utilities within roads or public right-of-ways should be placed in conformance with the requirements of the governing agency (water district, public works department, etc.). Utility trench backfill within private property should be placed in conformance with the provisions of this report. In general, service lines extending inside of property may be backfilled with native soils compacted to a minimum of 90% relative compaction. Backfill operations should be observed and tested to monitor compliance with these recommendations. 5.3 Slope Stability of Graded Slopes Unprotected, permanent graded slopes should not be steeper than 3:1 (horizontal:vertical) to reduce wind and rain erosion. Protected slopes with ground cover may be as steep as 2:1. However, maintenance with motorized equipment may not be possible at this inclination. Fill slopes should be overfilled and trimmed back to competent material. Slope stability calculations are not presented because of the expected minimal slope heights (less than 5 feet). EARTH SYSTEMS SOUTHWEST May 23, 2008 11 File No.: 11446-01 Doc. No.: 08-05-782 STRUCTURES In our professional opinion, structure foundations can be supported on shallow foundations bearing on a zone of properly prepared and compacted soils placed as recommended in Section 5.1. The recommendations that follow are based on very low expansion category soils. 5.4 Foundations Footing design of widths, depths, and reinforcing are the responsibility of the Structural Engineer, considering the structural loading and the geotechnical parameters given in this report. A minimum footing depth of 12 inches below lowest adjacent grade should be maintained. A representative of ESSW should observe foundation excavations before placement of reinforcing steel or concrete. Loose soil or construction debris should be removed from footing excavations before placement of concrete. 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). V➢ Continuous wall foundations, 12 -inch minimum width and 12 inches below grade: 1500 psf for dead plus design live loads Allowable increases of 200 psf per each foot of additional footing width and 300 psf fof each additional 0.5 foot of footing depth may be used up to a maximum value of 2500 psf. V ✓� 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 300 psf per each foot of additional footing width and 400 psf f9r each additional 0.5 foot of footing depth may be used up to a maximum value of 2500 psf.,/ \/A one-third ('/3) increase in the bearing pressure may be used when calculating resistance to wind or seismic loads. The allowable bearing values indicated are based on the anticipated maximum loads stated in Section 1.1 of this report. If the anticipated loads exceed these values, the geotechnical engineer must reevaluate the allowable bearing values and the grading requirements. ,/Minimum reinforcement for continuous wall footings should be two No. 4 steel reinforcing bars, one placed near the top and one placed near the bottom of the footing. This reinforcing is not intended to supersede any structural requirements provided by the structural engineer. Expected Settlement: Estimated total static settlement should be less than one -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. 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 0.30 of dead load may be used. An allowable passive equivalent fluid pressure of 300 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 EARTH SYSTEMS SOUTHWEST May 23, 2008 12 File No.: 11446-01 Doc. No.: 08-05-782 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 Sub rg ade: Concrete slabs -on -grade and flatwork should be supported by compacted soil placed in accordance with Section 5.1 of this report. Vapor Retarder: In areas of moisture sensitive floor coverings, an appropriate vapor retarder should be installed to reduce moisture transmission from the subgrade soil to the slab. For these areas, an impermeable membrane (10 -mil thickness) should underlie the floor slabs. The membrane should be covered with 2 inches of sand to help protect it during construction and to aid in concrete curing. The sand should be lightly moistened just prior to placing the concrete. Low -slump concrete should be used to help reduce the potential for concrete shrinkage. The effectiveness of the membrane is dependent upon its quality, the method of overlapping, its protection during construction, and the successful sealing of the membrane around utility lines. The following minimum slab recommendations are intended to address geotechnical concerns such as potential variations of the subgrade and are not to be construed as superseding any structural design. The design engineer and/or project architect should ensure compliance with SB800 with regards to moisture and moisture vapor. 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 to resist potential cracking. Concrete floor slabs may either be monolithically placed with the foundations or doweled after footing placement. The thickness and reinforcing given are not intended to supersede any structural requirements provided by the structural engineer. The project architect or geotechnical engineer should continually observe all reinforcing steel in slabs during placement of concrete to check for proper location within the slab. Control Joints: Control joints should be provided in all concrete slabs -on -grade at a maximum spacing of 36 times the slab. thickness (12 feet maximum on -center, each way) as recommended by American Concrete Institute (ACI) guidelines. All joints should form approximately square patterns to reduce the potential for randomly oriented contraction cracks. Contraction joints in the slabs should be tooled at the time of the pour or saw cut ('/4 of slab depth) as soon as practical and not more than 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. EARTH SYSTEMS SOUTHWEST May 23, 2008 13 File No.: 11446-01 Doc. No.: 08-05-782 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 We understand that proposed development plans for the remodel project include both restrained and cantilevered retaining walls including combinations of both. Special consideration should be given to design and construction sequencing where the surface area above the retained portion of the wall, particularly floor slabs, may be affected by settlement and wall rotation. 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 Granular Backfill Passive Pressure 300 pcf - level ground Active Pressure (cantilever walls) Use when wall is permitted to rotate 0.1 to 0.2% of wall 35 pcf - level ground height for granular backfill At -Rest Pressure restrained walls 55 pcf - level ground Dynamic Lateral Earth Pressure Acting at 0.6H, 15 pcf Where H is height of backfill in feet Base Lateral Sliding Resistance Base 0.30 load x Coefficient of Friction: Notes: 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. Drainage: A backdrain or an equivalent system of backfill drainage should be incorporated into the retaining wall design, whereby collected water is conveyed to an approved point of discharge. 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 EARTH SYSTEMS SOUTHWEST May 23, 2008 14 File No.: 11446-01 Doc. No.: 08-05-782 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 SubQrade 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. Sulfate and other salts can attack the cement within concrete causing weakening of the cement matrix and eventual deterioration by raveling. This attack can be in the form of a physical attack or chemical attack whereby there may be a chemical reaction between the sulfate and the cement used in the concrete. According to ACI 318 as referenced by the 2007 California Building Code, if sulfate concentrations exceed 1000 ppm there will be special requirements. For this project, the results of those samples tested. suggest a low sulfate ion concentration (50 ppm). Normal concrete mixes may be used. Electrical resistivity is a process whereby metal (ferrous) objects in direct contact with soil may be subject to attack by electrochemical corrosion. This typically pertains to buried metal pipes, valves, culverts, etc. made of ferrous metal. To avoid this type of corrosion or to slow the process, buried metal objects are generally protected with waterproof resistant barriers, i.e. epoxy corrosion inhibitors, asphalt coatings, cathodic protection, or encapsulating with densely consolidated concrete. Electrical resistivity testing of the soil suggests that the site soils may present a severe potential for metal loss from electrochemical corrosion processes. Chloride ions can cause corrosion of reinforcing steel. For this project, the results of those samples tested suggest a low chloride ion concentration (87 ppm). ACI 318 is referenced by the California Building Code, and provides commentary relative to the effects of chlorides present in the soil; from both internal and external sources. It is possible that long term saturation of foundations with chloride rich water could allow the chloride access to the reinforcing steel. A minimum concrete cover of cast -in-place concrete should be in accordance with Section 7.7 of the 2007 edition of ACI 318. Additionally, the concrete should be thoroughly vibrated during placement. 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. EARTH SYSTEMS SOUTHWEST May 23, 2008 15 File No.: 11446-01 Doc. No.: 08-05-782 5.8 Seismic Design Criteria This site is subject to strong ground shaking due to potential fault movements along the San Andreas, San Jacinto and other regional faults. Engineered design and earthquake -resistant construction increase safety and allow development of seismic areas. The minimum seismic design should comply with the 2007 edition of the California Building Code and ASCE 7-05 using the seismic coefficients given in the table below. 2007 CBC (ASCE 7-05) Seismic Parameters 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 may evaluate the level of risk and performance that is acceptable. Performance based criteria could be set in the design. The design engineer should exercise special care so that all components of the design are fully met with attention to providing a continuous load path. An adequate quality assurance and control program is urged during project construction to verify that the design plans and good construction practices are followed. This is especially important for sites lying close to the major seismic sources. Estimated peak horizontal site accelerations based upon a probabilistic analysis (10% probability of occurrence in 50 years) is approximately 0.48 g for a stiff soil site. Actual accelerations may be more or less than estimated. Vertical accelerations are typically 1/3 to % of the horizontal accelerations, but can equal or exceed the horizontal accelerations, depending upon the local site effects and amplification. EARTH SYSTEMS SOUTHWEST Reference i Seismic Category: D Table 1613.5.6 /Seismic Class: D Table 1613.5.2 Maximum Considered Earthquake (MCE) Ground Motion /Short Period Spectral Response SS: 1.50 g Figure 1613.5 / 1 second Spectral Response, S,: 0.60 g Figure 1613.5 Site Coefficient, Fa: 1.00 Table 1613.5.3(1) /Site Coefficient, F': 1.50 Table 1613.5.3(2) Design Earthquake Ground Motion Short Period Spectral Response, SDs 1.00 g A second Spectral Response, SDI 0.60 g 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 may evaluate the level of risk and performance that is acceptable. Performance based criteria could be set in the design. The design engineer should exercise special care so that all components of the design are fully met with attention to providing a continuous load path. An adequate quality assurance and control program is urged during project construction to verify that the design plans and good construction practices are followed. This is especially important for sites lying close to the major seismic sources. Estimated peak horizontal site accelerations based upon a probabilistic analysis (10% probability of occurrence in 50 years) is approximately 0.48 g for a stiff soil site. Actual accelerations may be more or less than estimated. Vertical accelerations are typically 1/3 to % of the horizontal accelerations, but can equal or exceed the horizontal accelerations, depending upon the local site effects and amplification. EARTH SYSTEMS SOUTHWEST May 23, 2008 16 File No.: 11446-01 Doc. No.: 08-05-782 Section 6 LIMITATIONS AND ADDITIONAL SERVICES 6.1 Uniformity of Conditions and Limitations Our findings and recommendations in this report are based on selected points of field exploration, laboratory testing, and our understanding of the proposed project. Furthermore, our findings and recommendations are based on the assumption that soil conditions do not vary significantly from those found at specific exploratory locations. Variations in soil or groundwater conditions could exist between and beyond the exploration points. The nature and extent of these variations may not become evident until construction. Variations in soil or groundwater may require additional studies, consultation, and possible revisions to our recommendations. Findings of this report are valid as of the issued date of the report. However, changes in conditions of a property can occur with passage of time, whether they are from natural processes or works of man, on this or adjoining properties. In addition, changes in applicable standards occur, whether they result from legislation or broadening of knowledge. Accordingly, findings of this report may be invalidated wholly or partially by changes outside our control. Therefore, this report is subject to review and should not be relied upon after a period of one year. In the event that any changes in the nature, design, or location of structures are planned, the conclusions and recommendations contained in this report shall not be considered valid unless the changes are reviewed and the conclusions of this report are modified or verified in writing. This report is issued with the understanding that the owner or the owner's representative has the responsibility to bring the information and recommendations contained herein to the attention of the architect and engineers for the project so that they are incorporated into the plans and specifications for the project. The owner or the owner's representative also has the responsibility to verify that the general contractor and all subcontractors follow such recommendations. It is further understood that the owner or the owner's representative is responsible for submittal of this report to the appropriate governing agencies. As the Geotechnical Engineer of Record for this project, Earth Systems Southwest (ESSW) has striven to provide our services in accordance with generally accepted geotechnical engineering practices in this locality at this time. No warranty or guarantee is express or implied. This report was prepared for the exclusive use of the Client and the Client's authorized agents. ESSW should be provided the opportunity for a general review of final design and specifications in order that earthwork and foundation recommendations may be properly interpreted and implemented in the design and specifications. If ESSW is not accorded the privilege of making this recommended review, we can assume no responsibility for misinterpretation of our recommendations. EARTH SYSTEMS SOUTHWEST May 23, 2008 17 File No.: 11446-01 Doc. No.: 08-05-782 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. Maintaining ESSW as the geotechnical consultant from beginning to end of the project will provide continuity of services. The geotechnical engineering firm providing tests and observations shall assume the responsibility of Geotechnical Engineer of Record. Construction monitoring and testing would be additional services provided by our firm. The costs of these services are not included in our present fee arrangements, but can be obtained from our office. The recommended review, tests, and observations include, but are not necessarily limited to, the following: • Consultation during the final design stages of the project. • A review of the building and grading plans to observe that recommendations of our report have been properly implemented into the design. • Observation and testing during site preparation, grading, and placement of engineered fill as required by CBC Sections 1704.7 and Appendix J or local grading ordinances. • Consultation as needed during construction. •1• Appendices as cited are attached and complete this report. EARTH SYSTEMS SOUTHWEST May 23, 2008 18 File No.: 11446-01 Doc. No.: 08-05-782 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), 2004, ACI Manual of Concrete Practice, Parts 1 through 5. American Concrete Institute (2004) "Building Code Requirements for Structural Concrete (ACI 318-05) and Commentary (ACI 318R-05)." American Society of Civil Engineers (ASCE), 2006, Minimum Design Loads for Buildings and Other Structures, ASCE 7-05. California Department of Water Resources, 1964, Coachella Valley Investigation, Bulletin No. 108, 146 pp. 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. 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), 2007, California Building Code, 2007 Edition. Jennings, C.W, 1994, Fault Activity Map of California and Adjacent Areas: California Division of Mines and Geology, Geological Data Map No. 6, scale 1:750,000. Petersen; M.D., Bryant, W.A., Cramer, C.H., Cao, T., Reichle, M.S., Frankel, A.D., Leinkaemper, J.J., McCrory, P.A., and Schwarz, D.P., 1996, Probabilistic Seismic Hazard Assessment for the State of California: California Division of Mines and Geology Open -File Report 96-08. Riverside County Planning Department, 2002, Geotechnical Element of the. Riverside County General Plan — Hearing Draft. Rogers, T.H., 1966, Geologic Map of California - Santa Ana Sheet, California Division of Mines and Geology Regional Map Series, scale 1:250,000. EARTH SYSTEMS SOUTHWEST May 23, 2008 19 File No.: 11446-01 Doc. No.: 08-05-782 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. United States Department of Homeland Securities, FEMA Map Center, flood map number 0602451625C, Riverside CO, dated November 20, 1996. 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 APPENDIX A Figure 1 — Site Location Map Figure 2 — Boring Location Map Table 1 — Fault Parameters Terms and Symbols used on Boring Logs Soil Classification System Logs of Borings EARTH SYSTEMS SOUTHWEST Referencc: www.tcrrascrvcr-usa.com, 7 km SW oflndio, California, United States,, dated.July 1, 1980. C? 2 Figure 1 Site Location 56-150 PGA Boulevard PGA West Stadium Clubhouse Remodel La Quinta, Riverside County,California Approximate Scale: 1" = 2,000' Earth Systems 0 Southwest 0 2,000' 4,000' 05/23/08 1 File No.: 11446-01 y � 27 Figure 1 Site Location 56-150 PGA Boulevard PGA West Stadium Clubhouse Remodel La Quinta, Riverside County,California Approximate Scale: 1" = 2,000' Earth Systems 0 Southwest 0 2,000' 4,000' 05/23/08 1 File No.: 11446-01 Reference: DigitalGlobc aerial image. LFigure 2 LEGEND Boring Location 56-150 PGA Boulevard B-3 Approximate Boring Locations PGA West Stadium Clubhouse Remodel La Quinta, Riverside County,California Approximate Scale: V= 65' Earth Systems I MOMOMMMM%0Southwest 0 65' 130' 05/23/08 1 File No.: 11446-01 Southwest 79-811 U Country Club Drive, Bermuda Dimes, CA 92203 Phone (760) 345-1588, Fax (760) 345-7315 Boring No: B-1 Drilling Date: April 25, 2008 Project Mame: 56-150 PGA Boulevard, La Quinta, CA Drilling Method: 8" Hollow Stem Auger File Number: 11446-01 Drill Type:. Simco 2800 Boring Location: See Figure 2 Logged By: Dirk Wiggins Sample i Type Penetration _ y Description of Units Page t of t w O U _. oResistance £ q fl .o y Note: The stratification lines shown represent the w o T a �,� o approximate boundary between soil and/or rock types Graphic Trend A m' No (Blows/6") N q U and the transition may be gradational. Blow Dry Count Density Earth Systems 10 • • • 15 • • 20 • • • 25 • • 30 35 • • 40 • 45 • 50 • • 55 • • 60 SM/ML SILTY SAND TO SANDY SILT: pale yellowish brown, medium dense, moist, fine grained, sonic sandy silt, grass on surface 18,16,20 102 7 dense 5,12,15 101 5 medium dense damp, fine to medium grained 8,12,17 106 4 line grained, some medium grained sand 7,14,18 100 6 dense 3.2.2 -- 29 ML SILT: light olive gray to moderate yellowish brown, soil, moist to wct, sonic very fine grained sand, slightly clayey SM SILTY SAND: light olive gray, medium dense, moist, line grained 7,10,14 100 7 lenses of sandy silt 5,7,10 pale yellowish brown loose 11,16,19 pale to moderate yellowish brown, dense 10,15,11 medium dense, fine to medium grained 13,19,17 SP -SM SAND WITH SILT: moderate yellowish brown, dense, damp, fine to medium grained 4,5,6 ILI ML SANDY SILT: light olive gray, median dense, damp, line grained, lenses of clay and silty clay Total Depth 51.5 feet No Groundwater Encountered Earth Systems *►'�� Southwest -5 • 15 - 20 -25 - 30 - 35 -40 -45 50 • 55 • 60 �'. 79-811 B Country Club Drive, 13canuda DMICS, CA 92203 Phonc (760) 345-1588, Pax (760) 345-7315 Boring No: B-2 SM Drilling Date: April 25, 2008 Project Name: 56-150 PGA Boulevard, La Quinta, CA SILTY SAND: pale to moderate yellowish brown, dense, damp, fine grained Drilling Method: 8" Hollow Stcm Auger File Number: . 11446-01 Drill Type: Simco 2800 Boring Location: See Figure 2 Logged By: Dirk Wiggins 2 Sample Y Page 1 1 v yp Type Penetration 5 of Description of Units SP -SM "Resistance v q v u Y .y Note: The stratification lines shown represent the Q T �' a � o approximate boundary between soil and/or rock types Graphic Trend o . tBlows/6) CO yr ( rn p t:J and the Iransition may be gradational. Blow Dry 6,8,31 105 3 Count Density -5 • 15 - 20 -25 - 30 - 35 -40 -45 50 • 55 • 60 �'. SM 4 SILTY SAND: pale to moderate yellowish brown, dense, damp, fine grained 9,17,22 106 2 fine to medium grained 7,12,17 102 5 SP -SM SAND WITH SILT: pale yellowish brown, medium dense, damp, fisc grained 6,8,31 105 3 SM SILTY SAND: pale yellowish brown, dense, damp, fine grained 6,7,9 91 5 medium dense 5, 12,9 90 26 silt and clay lenses 6,11,26 CL 99 13 SILTY CLAY: moderate brown, very stiff, damp, lenses of sandy silt . light olive gray SM SILTY SAND: moderate yellowish brown, medium dense, clamp, Ll5.4,7 -- 6 fine to median grained, trace coarse grained, trace fine gravel Total Depth 31.5 feet No Groundwater Encountered Are kkl Earth Systems d Southwest Boring No: B-3 Drilling Date: April 25, 2008 Project Name: 56-150 PGA Boulevard, La Quinta, CA File Number: 11446-01 Boring Location: See Figure 2 Drill Type: Simco 2800 4 Sample Type Penetration Logged By: Dirk Wiggins Description of Units sn t c� Resistance U vi °c a A m 0 (Blows/6") V IS p v V 6,20,44 113 - 10 - 15 -20 -25 - 30 - 35 -40 -45 - 50 -'55 -60 79-811 B Country Club Drivc, Bennuda Dunes. CA 92203 Phone (760) 345-1588, Far (760) 345-7315 Drilling Date: April 25, 2008 SM Drilling Method: 8" Hollow Stem Auger SILTY SAND: dark yellowish brown, medium dense, damp, fine Drill Type: Simco 2800 Logged By: Dirk Wiggins Description of Units Page 1 or t Note: The stratification lines shown represent the approximate boundary between soil and/or rock types Graphic Trend and the trnnsition may be gradational. Blow Dry Count Density SM SILTY SAND: dark yellowish brown, medium dense, damp, fine 6,10,10 13 grained, lenses of sandy silt IS 6,20,44 113 7 dense, trace medium grained 6,9,12 T. 97 7 modemic yellowish brown, medium dense 6,10,15 117 7 black micas present 5.7.9 MUCL 31 CLAYEY SILT: dark yellowish brown, medium dense, damp, fine grained sand, lenses of silty clay Total Depth 21,5 feet No Groundwater Encountered PGA West Stadium Clubhouse Remodel, La Quinta, CA .11446-01 Table 1 Fault Parameters & Deterministic Estimates of Mean Peak Ground Acceleration (PGA) Fault Name or Seismic Zone Distance from Site (mi) (km) Gault Type Maximum Magnitude Mlitax (Mw) Avg Slip Rate (uunlyr) Avg Return Period (Yrs) Fault Length (km) Mean Site PGA (t;) Reference Notes: 1 (2) (3 4) 2 2) (2) (5 San Andreas - Southern 7.8 12.6 SS A 7.7 24 220 199 0.36 San Andreas - Banning Branch 9.9 15.9 SS A 7.2 10 220 98 0.27 San Andreas - Mission Crk. Branch 9.9 15.9 SS A 7.2 25 220 .95 0.27 San Jacinto (Hot Spgs - Buck Ridge) 14.4 23.1 SS C 6.5 2 354 70 0.14 Sart Jacinto-Anza 18.3 29.5 SS A 7.2 12 250 91 0.16 Blue Cut 18.5 29.7 SS C 6.8 1 760 30 0.13 San Jacinto-Coyotc Creek . 19.5 31.3 SS B 6.8 4 175 41 0.13 Burnt Mtn. 22.0 35.4 SS B 6.5 0.6 5000 21 0.10 Eureka Peak 22.9 36.9 SS B 6.4 0.6 5000 19 0.09 San Jacinto - Borrego 30.7 49.4 SS B 6.6 4 175 29 0.07 Morongo 33.2 53.4 SS C 6.5 0.6 1170 23 0.06 Pinto Mountain 34.8 56.0 SS B 7.2 2.5 499 74 0.09 Emerson So. - Copper Mtn. 35.9 57.7 SS B 7.0 0.6 5000 54 0.08 Earthquake Valley 36.8 59.3 SS B 6.5 2 351 20 0.06 Landers 37.1 59.7 SS B 7.3 0.6 5000 83 0.09 Pisgah -Bullion Mtn. -Mesquite Lk 37.2 59.8 SS B 7.3 0.6 5000 89 0.09 Brawley Seismic Zone 37.7 60.7 SS B 6.4 25 24 42 0.05 San Jacinto -San Jacinto Valley 38.4 61.9 SS B 6.9 12 83 43 0.07 Elsinore -Julian 41.4 66.6 SS A 7.1 5 340 76 0.07 North Frontal Fault Zone (East) 43.2 69.5 RV B 6.7 0.5 1727 27 0.07 Elmore Ranch 45.6 73.4 SS B 6.6 1 225 29 0.05 Elsinore -Coyote Mountain 47.1 75.8 SS B 6.8 4 625 39 0.05 Elsinore -Temecula 47.1 75.9 SS B 6:8 5 240 43 0.05 Johnson Valley (Northern) 47.9 77.1 SS 13 6.7 0.6 5000 35 0.05 Superstition Mtn. (San Jacinto) 48.8 78.6- SS B 6.6 5 500 24 0.05 Calico - Hidalgo 49.5 79.6 SS. B 7.3 0.6 5000 95 0.07 Superstition Hills (San Jacinto) 49.7 80.0 SS 13 6.6 4 250 23 0.05 Lenwood-Lockhart-Old Woman Sprgs 53.7 86.4 SS B 7.5 0.6 5000 145 0.07 North Frontal Fault Zone (West) 54.0 86.9 RV B 7.2 . 1 1314 50 0.08 Helendale - S. Lockhardt 61.3 98.7 SS B 7.3 0.6 5000 97 0.06 San Jacinto -San Bernardino 61.8 99.5 SS B 6.7 12 100 36 0.04 Weinert (Superstition Hills) 61.9 99.6 SS C 6.6 4 250 22 0.04 Notes: I. Jennings(1994)and California Geologic Survey (CGS) (2003) 2. CGS (20031 SS = Strike -Slip, RV =Reverse, DS =Dip Slip (normal), BT= Blind lhntst 3. 2001 CBC, where Type A faults: Mmax > 7 & slip rate >5 mm/yr & TYpc C faults: Mmax <6.5 & slip rate < 2 nun/yr 4. CGS (2003) 5. llrc estimates of the mean Site PGA are based on the following attenuation relationships: Average of: (1) 1997 Boore, Joyner & Pwnal; (2) 1997 Sadigh d al; (3) 1997 Campbell , (4) 1997 Abrahamson & Silva (mean plus sigma values are about 1.5 to 1:61itnes higher) Based on Site Coordinates: 33.642 N Latitude, 116.258 W Longlude and Site Soil Type D EARTH SYSTEMS SOUTHWEST DESCRIPTIVE SOIL CLASSIFICATION Soil classification is based on ASTM Designations D 2487 and D 2488 (Unified Soil Classification System). Information on each boring log is a compilation of subsurface conditions obtained from the field as well as from laboratory testing of selected samples. The indicated boundaries between strata on the boring logs are approximate only and may be transitional. SOIL GRAIN SIZE U.S. STANDARD SIEVE 12" 3" 3/4° 4 10 40 200 BOULDERS COBBLES GRAVEL SAND SILT CLAY COARSE FINE COARSE MEDIUM FINE 305 76.2 19.1 4.76 2.00 0.42 0.074 SOIL GRAIN SIZE IN MILLIMETERS 0.002 RELATIVE DENSITY OF GRANULAR SOILS (GRAVELS, SANDS, AND NON -PLASTIC SILTS) Very Loose "N=0-4 RD=0-30 Easily push a 1/2 -inch reinforcing rod by hand Loose N=5-10 RD=30-50 Push a 1/2 -inch reinforcing rod by hand Medium Dense N=11-30 RD=50-70 Easily drive a 1/2 -inch reinforcing rod with hammer Dense N=31-50 RD=70-90 Drive a 1/2 -inch reinforcing rod 1 foot with difficulty by a hammer Very Dense N>50 RD=90-100 Drive a 1/2 -inch reinforcing rod a few inches with hammer *N=Blows per foot in the Standard Penetration Test at 60% theoretical energy. For the 3 -inch diameter Modified California sampler, 140 -pound weight, multiply the blow count by 0.63 (about 2/3) to estimate N. If automatic hammer is used, multiply a factor of 1.3 to 1.5 to estimate N. RD=Relative Density (%). C=Undrained shear strength (cohesion). CONSISTENCY OF COHESIVE SOILS (CLAY OR CLAYEY SOILS) Very Soft "N=0-1 "C=0-250 psf Squeezes between fingers Soft N=24 C=250-500 psf Easily molded by finger pressure Medium Stiff N=5-8 C=500-1000 psf Molded by strong finger pressure Stiff N=9-15 C=1000-2000 psf Dented by strong finger pressure Very Stiff N=16-30 C=2000-4000 psf Dented slightly by finger pressure Hard N>30 C>4000 Dented slightly by a pencil point or thumbnail MOISTURE DENSITY Moisture Condition: An observational term; dry, damp, moist, wet, saturated. Moisture Content: The weight of water in a sample divided by the weight of dry soil in the soil sample expressed as a percentage. Dry Density: The pounds of dry soil in a cubic foot. MOISTURE CONDITION RELATIVE PROPORTIONS Dry ..........:..........Absence of moisture, dusty, dry to the touch Trace ............. minor amount (<5%) Damp................Slight indication of moisture with/some...... significant amount Moist.................Color change with short period of air exposure (granular soil) modifier/and...sufficient amount to Below optimum moisture content (cohesive soil) influence material behavior Wet....................High degree of saturation by visual and touch (granular soil) (Typically >30%) Above optimum moisture content (cohesive soil) Saturated .......... Free surface water LOG KEY SYMBOLS PLASTICITY Bulk, Bag or Grab Sample DESCRIPTION FIELD TEST Nonplastic A 1/8 in. (3 -mm) thread cannot be rolled Standard Penetration Split Spoon Sampler Low at any moisture content. The thread can barely be rolled. (2' outside diameter) Medium The thread is easy to roll and not much Modified California Sampler time is required to reach the plastic limit. ' (3° outside diameter) High The thread can be rerolled several times after reaching the plastic limit. No Recovery GROUNDWATER LEVEL Water Level (measured or after drilling) Terms and Symbols used on Boring L 7 Water Level (during drilling) r GRAPHIC LETTERSYMBOL MAJOR DIVISIONS SYMBOL TYPICAL DESCRIPTIONS Well-graded gravels, gravel-sand CLEAN •':':':':':':': GW mixtures, little or no fines GRAVELS < 5% FINES GRAVEL AND r• r• r• �r• r. r. ■: r• +• +• ..• + +• .• .. GP Poorly-graded gravels, gravel-sand GRAVELLY +r++i 'r:'•. mixtures. Little or no fines SOILS w.•;r•r.•w••r• r• r• r• +....... +... +. +. GM Silty gravels, gravel-sand-silt COARSE More than 50% of GRAVELS . . .. _ •' mixtures GRAINED SOILS coarse fraction WITH FINES > 12% FINES ✓y-y retained on No. 4 sieve y y GC Clayey gravels, gravel-sand-clay mixtures �' �3�'sJs SW Well-graded sands, gravelly sands, SAND AND CLEAN SAND little or no fines SANDY SOILS (Little or no fines) <5% Poorly-graded sands, gravelly More than 50% of sands, little or no fines material is lar er than No. 200 sieve size SAND WITH FIN ES SM Silty sands, sand-silt mixtures More than 50% of (appreciable coarse fraction amount of fines) ap ssin9 No. 4 sieve 12% SC Clayey sands, sand-clay mixtures Inorganic silts and very fine sands, ML rock flour, silty low clayey fine sands or clayey silts with slight plasticity LIQUID LIMIT Inorganic clays of low to medium FINE-GRAINED LESS THAN 50 CL plasticity, gravelly clays, sandy SOILS clays, silty clays, lean clays OL Organic silts and organic silty clays of low plasticity SILTS AND CLAYS Inorganic silty, micaceous, or 061 MH diatomaceous fine sand or silty soils 50% or more ofLIQUID is smaller than No. 200 LIMITmaterial GREATER CHInorganic clays of high plasticity, fat clays XX sieve size THAN 50 Organic clays of medium to high ............ plasticity, organic silts yyyyyyyyyyyyV rarraaarrraro Peat, humus, swamp soils with HIGHLY ORGANIC SOILS rrrarryarrra PT organichi h contents 9 .rrrr.rr,rr,rrrr� VARIOUS SOILS AND MAN MADE MATERIALS Fill Materials MAN MADE MATERIALS Asphalt and concrete Soil Classification System Earth Systems Southwest APPENDIX B Laboratory Test Results EARTH SYSTEMS SOUTHWEST File No.: 11446-01 May 23, 2008 Lab No.: 08-0209 UNIT DENSITIES AND MOISTURE CONTENT ASTM D2937 & D2216 Job Name: 56-150 PGA Blvd. - Clubhouse, La Quinta, CA Sample Depth Location (feet) Unit Dry Density (pcf) Moisture Content N USCS Group Symbol SM/ML SM/ML SM/ML SM/ML ML ML B 1 B1 B 1 B 1 B 1 B 1 2.5 5 10 15 20 25 102 101 106 100 --- 100 7 5 4 6 29 7 SM/ML SM/ML SM/ML SM/ML ML ML B2 1 --- 4 SM B2 2.5 106 2 SM B2 5 102 5 SM . B2 10 105 3 SM B2 15 91 5 SM B2 20 90 26 ML B2 25 99 13 CL B2 30 --- 6 SM B3 1 --- 13 sm B3 3 --- 15 SM B3 5 113 7 SM B3 10 97 7 SM B3 15 117 7 SM B3 20 --- 31 ML/CL EARTH SYSTEMS SOUTHWEST File No.: 11446--01 May 23, 2008 Lab No.: 08-0209 PARTICLE SIZE ANALYSIS ASTM D-422 Job Name: 56-150 PGA Blvd. - Clubhouse, La Quinta, CA Sample ID: B1 t✓i 1-4 feet Description: Brown Clayey Silt and Sand (SM/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 #30 98 #50 93 #100 70 #200 50 % Gravel: 0 % Sand: 50 % Silt: 32 % Clay (3 micron): 18 (Clay content by short hydrometer method) 100 I� 90 - - - - - - --' 80 - - — -- - - I- - -- 70 _; __ - _- ._ - -_�_ ___.- _.. 60- H � I 50- — - — c 40- 30 0 30 20 ---- - --- _ __ - - - --- 10 - - - - - - - E . --- a - - 0 li I I 100 10 1. 0.1 0.01 0.001 Particle Size ( nun) EARTH SYSTEMS SOUTHWEST File No.: 11446-01 Lab No.: 08-0209 May 23, 2008 CONSOLIDATION TEST ASTM D 2435 & D 5333 56-150 PGA Blvd. - Clubhouse, La Quinta, CA Initial Dry Density: 101.7 pcf B -I @ 25 feet Initial Moisture, %: 7.3% Brown Silty Sandy (SM) Specific Gravity (assumed): 2.67 Initial Void Ratio: 0.640 Ring Sample 2 1 0 -I -8 -9 -10 Hydrocollapse: 0.6% @ 2.0 ksf % Change in Height vs Normal Presssure Diagram —1—Before Saturation --I Hydrocol lapse � — a After Saturation ---M Rebound 'I 1.0 Vertical Effective Stress, ksf EARTH SYSTEMS SOUTHWEST 10.0 File No.: 11446-01 Lab No.: 08-0209 May 23, 2008 CONSOLIDATION TEST ASTM D 2435 & D 5333 56-150 PGA Blvd. - Clubhouse, La Quinta, CA Initial Dry Density: 92.1 pcf B-2 @ 20 feet Initial Moisture, %: 26.1 % Silty Sand, fine grained (SM) Specific Gravity (assumed): 2.67 Initial Void Ratio: 0.810 Ring Sample 2 1 0 -1 -2 -8 Hydrocollapse: 0.1 % @ 2.0 ksf % Change in Height vs Normal Presssure Diagram —a—Before Saturation°'` `w` = Hydrocollapse 0 After Saturation i! Rebound 0. t 1.0 Vertical Effective Stress, ksf EARTH SYSTEMS SOUTHWEST 10.0 File No.: 11446-01 May 23, 2008 Lab No.: 08-0209 MAXIMUM DENSITY / OPTIMUM MOISTURE ASTM D 1557-91 (Modified) Job Name: 56-150 PGA Blvd. - Clubhouse, La Quinta, CA Procedure Used: A Sample ID: 1 Preparation Method: Moist Location: B 1 @ 1-4 feet Rammer Type: Mechanical Description: Brown Clayey Silt and Sand . Lab Numbe 08-0209 (SM/ML) Sieve Size % Retained Maximum Density: 127.5 pcf 3/4" 0.0 Optimum Moisture: 10.5% 3/8" 0.0 #4 0.0 140 135 130 125 110 105 100 0 5 10 15 20 25 Moisture Content, percent EARTH SYSTEMS SOUTHWEST 30 35 i�mum 5 10 15 20 25 Moisture Content, percent EARTH SYSTEMS SOUTHWEST 30 35 File No.: 11446-01 Corrosivity May 23, 2008 Lab No.: 08-0209 Degree of Corrosivit Soluble SOIL CHEMICAL ANALYSES Low Sulfates 1000 - 2000 mg/Kg (ppm) [0.1-0.2%] Job Name: 56-150 PGA Blvd. - Clubhouse, La Quinta, CA Job No.: 11446-01 > 20,000 mg/Kg (ppm) [>2.0%] Sample 1D: B1 1-1000 ohm -cm Sample Depth, feet: 1-4 DF RL Sulfate, mg/Kg (ppm): 50 1 0.50 Chloride, mg/Kg (ppm): 87 1 0.20 pH, (pH Units): 8.80 1 0.41 Resistivity, (ohm -cm): 1,625 N/A N/A Conductivity, (µmhos -cm): 11 2.00 Note: Tests performed by Subcontract Laboratory: Surabian AG Laboratory DF: Dilution Factor 105 Tesori Drive RL: Reporting Limit Palin Desert, California 92211 Tel: (760) 200-4498 General Guidelines for Soil Corrosivity Chemical Agent Amount in Soil Degree of Corrosivit Soluble 0 -1000 mg/Kg (ppm) [ 0-.1%] Low Sulfates 1000 - 2000 mg/Kg (ppm) [0.1-0.2%] Moderate 2000 - 20,000 mg/Kg (ppm) [0.2-2.0%] Severe > 20,000 mg/Kg (ppm) [>2.0%] Very Severe Resistivity 1-1000 ohm -cm Very Severe 1000-2000 ohm -cm Severe 2000-10,000 ohm -cm Moderate 10,000+ ohm -cm Low EAR'T'H SYSTEMS SOUTHWEST