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06-2055 (OFC) Geotechnical Engineering ReportKLEINE BUILDING AND DEVELOPMENT, INC. 41-910 BOARDWALK, SUITE A10 PALM DESERT, CALIFORNIA 92211 GEOTECHNICAL ENGINEERING REPORT PROPOSED CORPORATE CENTER SOUTHEAST CORNER OF CORPORATE CENTRE DRIVE AND COMMERCE COURT LA QUINTA, CALIFORNIA August 11, 2003 © 2003 Earth Systems Southwest Unauthorized use or copying of this document is strictly prohibited without the express written consent of Earth Systems Southwest. File No.: 09285-01 03-07-830 4R 0Earth Systems �7e Southwest August 11, 2003 Kleine Building and Development, Inc. 41-910 Boardwalk, Suite A10 Palm Desert, California 92211 Attention: Mr. Neil Kleine 79-811B Country Club Drive Bermuda Dunes, CA 92201 (760) 345-1588 (800)924-7015 FAX (760) 345-7315 File No.: 09285-01 03-07-830 Project: Proposed Corporate Professional Center Southwest corner of Corporate Centre Drive and Commerce Court La Quinta, California Subject: GEOTECHNICAL ENGINEERING REPORT Reference: Slad� demon _Engineering, Geotechnical Investigation for La ,Quinta Corporate Center, LQuinta, California, dated October 13, 1999, Project No.: 99-10-167. Dear Mr. Kleine: We take pleasure to present this Geotechnical Engineering Report prepared for the proposed commercial buildings to be located on south side of Corporate Centre Drive and east of Commerce Court in the City of La Quinta, California. This report presents our findings and recommendations for site grading and preliminary foundation design, incorporating the information provided to our office. The site is suitable for the proposed development provided the recommendations in this report are followed in design and construction. In general, the upper soils should be compacted to improve bearing capacity and reduce settlement. The site is subject to strong ground motion from the San Andreas Fault. Testing of near surface soils indicates a low sulfate content, however test results on soils in the vicinity of site indicate moderate sulfate content. Based upon soil chemical analyses, there is a severe to a very severe potential for corrosivity. This report should stand as a whole, and no part of the report should be excerpted or used to the exclusion of any other part. This report completes our scope of services in accordance with our agreement, dated July 1, 2003. Other services that may be required, such as plan review and grading observation, are additional services and will be billed according to our Fee Schedule in effect at the time services are provided. Unless requested in writing, the client is responsible to distribute this report to the appropriate governing agency or other members of the design team. August 11, 2003 - 2 - File No.: 09285-01 03-07-830 We appreciate the opportunity to provide our professional services. Please contact our office if there are any questions or comments concerning this report or its recommendations. Respectfully submitted, EARTH SYSTEMS SOUTHWEST Reviewed by, so G'j� / KARL A. 00. Karl Harmon LU HARMON N 4gS.ill EG2243 n: No. EG 2243 CE 38234 SER/cds/csh/nrm CERTIFIED ENGINEERING Q N� GEOLOGIST 9TF OF CAS -%I< Distribution: 6/Mr. Neil Kleine 1/SJC File 2/1313 File EARTH SYSTEMS SOUTHWEST Q�OF S/pN Q�O Or1 L.. S ZIr9gl F2 2v l l2 2m m LU cn No. 266 cr-Exp. 6-30-04 F'OTECHW-' \ 9TFOF CA \F\) 3 TABLE OF CONTENTS Page Section1 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 Seconda Hazards......................................................................................6 -- - _rY 3.4.3 Site Acceleration and Seismic Coefficients ............................................... .e 7 Section4 CONCLUSIONS.....................................................................................................9 Section 5 RECOMMENDATIONS......................................................................................11 SITE DEVELOPMENT AND GRADING......................................................................11 5.1 Site Development - Grading..................................................................................11 5.2 Excavations and Utility Trenches..........................................................................12 5.3 Slope Stability of Graded Slopes...........................................................................13 STRUCTURES................................................................................................................13 5.4 Foundations...........................................................................................................13 5.5 Slabs-on-Grade......................................................................................................14 5.6 Mitigation of Soil Corrosivity on Concrete...........................................................15 5.7 Pavements......................................................................:.......................................15 Section 6 LIMITATIONS AND ADDITIONAL SERVICES...........................................17 6.1 Uniformity of Conditions and Limitations............................................................17 6.2 Additional Services................................................................................................18 REFERENCES...............................................................................................................19 APPENDIX A Site Location Map Boring Location Map Table 1 Fault Parameters Logs of Borings APPENDIX B Laboratory Test Results EARTH SYSTEMS SOUTHWEST C T August 11, 2003 File No.: 09285-01 03-07-830 GEOTECHNICAL ENGINEERING REPORT PROPOSED CORPORATE PROFESSIONAL CENTER SOUTHEAST CORNER OF CORPORATE CENTRE DRIVE AND COMMERCE COURT LA QUINTA, CALIFORNIA Section 1 INTRODUCTION 1.1 Project Description This Geotechnical Engineering Report has been prepared for a Corporate Professional Center development located along the south side of Corporate Centre Drive and east of Commerce Court in the City of La Quinta, California. This property encompasses approximately 1.2 acres of currently undeveloped land. This acreage is a part of a larger parcel of undeveloped land that continues to the east. A geotechnical investigation and report was completed on this larger parcel by Sladden Engineering and is referenced in our cover letter. Applicable data from that report has been included herein. Specific details regarding the proposed development were not provided to our office as of the writing of this report. We understand that the proposed development will consist of two, one story buildings with a square footage footprint of 5,910 and 8,142 as shown on the preliminary site plan dated May 29, 2003. Site development will include site grading, building pad preparation, underground utility installation, parking lot construction, driveway lanes, curb and sidewalk placement. Based upon existing site topography site grading is anticipated to be minimal, for site drainage improvement. We used maximum column loads of 50 kips and a maximum wall loading of 2.5 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 project site is irregular in shape and is located on the south side of Corporate Centre Drive and east of Commerce Court in the City of La Quinta, California. The site location is shown on Figure 1 in Appendix A. The project site presently consists of near level undeveloped land, with no surface evidence of structures. As a result of land leveling previous grading activities the site is essentially barren of vegetation. The Whitewater Channel alignment is located across from Corporate Centre Drive. The history of past use and development of the property was not investigated as part of our scope of services. No direct evidence of past development was observed on the site during our reconnaissance. Nonetheless, some previous development of the site is possible. Buried remnants such as old foundations, slabs, or septic systems may exist on the site. EARTH SYSTEMS SOUTHWEST August 11, 2003 - 2 - File No.: 09285-01 03-07-830 1.3 Purpose and Scope of Work The purpose for our services was to evaluate the site soil conditions and to provide professional opinions and recommendations regarding the proposed development of the site. The scope of work included the following: ➢ A general reconnaissance of the site. ➢ Shallow subsurface exploration by drilling 4 exploratory borings to depths ranging from 16.5 to 51.5 feet. ➢ Laboratory testing of selected soil samples obtained from the exploratory borings. ➢ Review of selected published technical literature pertaining to the site. ➢ Engineering analysis and evaluation of the acquired data from the exploration and testing programs. ➢ A summary of our findings and recommendations in this written report. This report contains the following: ➢ Discussions on subsurface soil and groundwater conditions. ➢ Discussions on regional and local geologic conditions. ➢ Discussions on geologic and seismic hazards. ➢ Graphic and tabulated results of laboratory tests and field studies. ➢ Recommendations regarding: • Site development and grading criteria, • Excavation conditions and buried utility installations, • Structure foundation type and design, • Allowable foundation bearing capacity and expected total and differential settlements, • Concrete slabs -on -grade, • Lateral earth pressures and coefficients, • Mitigation of the potential corrosivity of site soils to concrete and steel reinforcement, • Seismic design parameters, • Preliminary pavement structural sections. Not Contained In This Report: Although available through Earth Systems Southwest, the current scope of our services does not include: ➢ A corrosive study to determine cathodic protection of concrete or buried pipes. ➢ An environmental assessment. ➢ Investigation for the presence or absence of wetlands, hazardous or toxic materials in the soil, surface water, groundwater, or air on, below, or adjacent to the subject property. EARTH SYSTEMS SOUTHWEST C' August 11, 2003 - 3 - File No.: 09285-01 03-07-830 Section 2 METHODS OF INVESTIGATION 2.1 Field Exploration Four exploratory borings were drilled to depths ranging from 16.5 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 using 8 -inch outside diameter hollow -stem augers powered by a CME -45 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, hammer manually activated by rope and cathead, dropping 30 inches in general accordance with ASTM D 1586. Recovered soil samples were sealed in containers and returned to the laboratory. A bulk sample was also obtained from auger cuttings, representing a mixture of soils encountered at the depths noted. The final logs of the borings represent our interpretation of the contents of the field logs and the results of laboratory testing performed on the samples obtained during the subsurface exploration. The final logs are included in Appendix A of this report. The stratification lines represent the approximate boundaries between soil types although the transitions, however, may be gradational. 2.2 Laboratory Testing Samples were reviewed along with field logs to select those that would be analyzed further. Those selected for laboratory testing include soils that would be exposed and used during grading, and those deemed to be within the influence of the proposed structure. Test results are presented in graphic and tabular form in Appendix B of this report. The tests were conducted in general accordance with the procedures of the American Society for Testing and Materials (ASTM) or other standardized methods as referenced below. Our testing program consisted of the following: ➢ In-situ Moisture Content and Unit Dry Weight for the ring samples (ASTM D 2937). ➢ Particle Size Analysis (ASTM D 422) to classify and evaluate soil composition. The gradation characteristics of selected samples were made by hydrometer and sieve analysis procedures. ➢ Consolidation (Collapse Potential) (ASTM D 2435 and D 5333) to evaluate the compressibility and hydroconsolidation (collapse) potential of the soil. ➢ Chemical Analyses (Soluble Sulfates & Chlorides, pH, and Electrical Resistivity). EARTH SYSTEMS SOUTHWEST August 11, 2003 - 4 - File No.: 09285-01 03-07-830 Section 3 DISCUSSION 3.1 Soil Conditions The field exploration indicates that loose fill soils mantle the upper 3 to 5 feet of the site and consist primarily of fine-grained sand with buried construction debris. Below the fill material native soil consists of fine-grained silty sand with thin clay and silt interbeds to a maximum depth of approximately 51.5 feet below the ground surface. The upper sandy fill material was found to be in a moist to wet (B-3), varying from loose to a medium dense condition. In general, cleaner sands tend to be dry to moist and the fine-grained soils with a higher silt content tend to retain moisture. The native upper fine sandy soil represents wind blown aeolian sand; while the more fine grain interbedded sandy silts and clay represent lakebed sediments. The boring logs provided in Appendix A include a more detailed descriptions of the soils encountered. The soils are visually classified to be in the very low expansion (EI < 20) category in accordance with Table 18A -I -B of the California (Uniform) 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. A consolidation test indicates 1.8 % collapse upon inundation and is considered a medium site risk. The hydroconsolidation potential is commonly mitigated by recompaction of a zone beneath building pads. The site lies within a recognized blow sand hazard area. Fine particulate matter (PM10) can create an air quality hazard if dust is blowing. Watering the surface, planting grass or landscaping, or hardscape normally mitigates this hazard. 3.2 Groundwater Free groundwater was not encountered in the borings during exploration, or was encountered in the previous exploration in the general vicinity. 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 geomorphic province is the Salton Trough. The Salton Trough is a large northwest -trending structural depression that extends from San Gorgonio Pass, approximately 180 miles to the Gulf of California. Much of this depression in the area of the Salton Sea is below sea level. The Coachella Valley forms the northerly part of the Salton Trough. The Coachella Valley contains a thick sequence of sedimentary deposits that are Miocene to recent in age. Mountains surrounding the Coachella Valley include the Little San Bernardino Mountains on the northeast, EARTH SYSTEMS SOUTHWEST L August 11, 2003 - 5 - File No.: 09285-01 03-07-830 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 Geology: The project site is located in the southern portion of the Coachella Valley near the eastern flanks of the Santa Rosa Mountains. The project is located in an area that was once covered by the ancient Lake Cahuilla. The sediments in this area of the valley consist generally of fine to medium grained sands which are wind blown (aeolian) and finer grained soil such as clays and silts that are lake bed (lacustrine) in origin. 3.4 Geologic Hazards Geologic hazards that may affect the region include seismic hazards (ground shaking, surface fault rupture, soil liquefaction, and other secondary earthquake -related hazards), slope instability, flooding, ground subsidence, and erosion. A discussion follows on the specific hazards to this site. 3.4.1 Seismic Hazards Seismic Sources: Several active faults or seismic zones lie within 62 miles (100 kilometers) of the project site as shown on Table 1 in Appendix A. The primary seismic hazard to the site is strong groundshaking from earthquakes along the San Andreas and San Jacinto Faults. The Maximum Magnitude Earthquake (Mmax) listed is from published geologic information available for each fault (Cao, et. al, CGS, 2003). The Mmax corresponds to the maximum earthquake believed to be tectonically possible. Surface Fault Rupture: The project site does not lie within a currently delineated State of California, Alquist-Priolo Earthquake Fault Zone (Hart, 1997). Well -delineated fault lines cross through this region as shown on California Geological Survey (CGS)) maps (Jennings, 1994). Therefore, active fault rupture is unlikely to occur at the project site. While fault rupture would most likely occur along previously established fault traces, future fault rupture could occur at other locations. Historic Seismicity: Six historic seismic events (5.9 M or greater) have significantly affected the Coachella Valley the last 100 years. They are as follows: • Desert Hot Springs Earthquake - On December 4, 1948, a magnitude 6.5 ML (6.OMW) earthquake occurred east of Desert Hot Springs. This event was strongly felt in the Palm Springs area. • Palm Springs Earthquake - A magnitude 5.9 ML (6.2MW) earthquake occurred on July 8, 1986 in the Painted Hills causing minor surface creep of the Banning segment of the San Andreas Fault. This event was strongly felt in the Palm Springs area and caused structural damage, as well as injuries. • Joshua Tree Earthquake - On April 22, 1992, a magnitude 6.1 ML (6.1MW) earthquake occurred in the mountains 9 miles east of Desert Hot Springs. Structural damage and minor injuries occurred in the Palm Springs area as a result of this earthquake. • Landers & 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 EARTH SYSTEMS SOUTHWEST August 11, 2003 - 6 - File No.: 09285-01 03-07-830 occurred just south of the town of Yucca Valley and extended some 43 miles toward Barstow. About three hours later, a magnitude 6.6 Ms (6.4MW) earthquake occurred near Big Bear Lake. No significant structural damage from these earthquakes was reported in the Palm Springs area. • Hector Mine Earthquake - On October 16, 1999, a magnitude 7.1 MW earthquake occurred on the Lavic Lake and Bullion Mountain Faults north of 29 Palms. This event while widely felt, no significant structural damage has been reported in the Coachella Valley. Seismic Risk: While accurate earthquake predictions are not possible, various agencies have conducted statistical risk analyses. In 2002, the California Geological Survey (CGS) and the United States Geological Survey (USGS) published probabilistic seismic hazard maps. We have used these maps in our evaluation of the seismic risk at the site. The Working Group of California Earthquake Probabilities (WGCEP, 1995) estimated a 22% conditional probability that a magnitude 7 or greater earthquake may occur between 1994 to 2024 along the Coachella segment of the San Andreas Fault. The primary seismic risk at the site is a potential earthquake along the San Andreas Fault. Geologists believe that the San Andreas Fault has characteristic earthquakes that result from rupture of each fault segment. The estimated characteristic earthquake is magnitude 7.7 for the Southern Segment of the fault. This segment has the longest elapsed time since rupture than any other part of the San Andreas Fault (USGS, 2002). The last rupture occurred about 1690 AD, based on dating by the USGS near Indio (WGCEP, 1995). This segment has also ruptured on about 1020, 1300, and 1450 AD, with an average recurrence interval of about 220 years. The San Andreas Fault may rupture in multiple segments producing a higher magnitude earthquake. Recent paleoseismic studies suggest that the San Bernardino Mountain Segment to the north and the Coachella Segment may have both ruptured together in 1450 and 1690 AD (WGCEP, 1995). 3.4.2 Secondary Hazards Secondary seismic hazards related to ground shaking include soil liquefaction, ground subsidence, tsunamis, and seiches. The site is far inland so the hazard from tsunamis is non- existent. At the present time, no water storage reservoirs are located in the immediate vicinity of the site. Therefore, hazards from seiches are considered negligible at this time. Soil Liquefaction: Liquefaction is the loss of soil strength from sudden shock (usually earthquake shaking), causing the soil to become a fluid mass. In general, for the effects of liquefaction to be manifested at the surface, groundwater levels must be within 50 feet of the ground surface and the soils within the saturated zone must also be susceptible to liquefaction. The potential for liquefaction to occur at this site is 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 liquefaction hazard zone. Ground Subsidence: The potential for seismically induced ground subsidence is considered to be moderately high at the site. Dry sands tend to settle and densify when subjected to strong earthquake shaking. The amount of subsidence is dependent on relative density of the soil, ground motion, and earthquake duration. Uncompacted fill areas may be susceptible to seismically induced settlement. EARTH SYSTEMS SOUTHWEST August 11, 2003 - 7 - File No.: 09285-01 03-07-830 Slope Instability: The site is relatively flat. Therefore, potential hazards from slope instability, landslides, or debris flows are considered negligible. Flooding: The project site does not lie within a designated FEMA 100 -year flood plain. The project site may be in an area where sheet flooding and erosion could occur. If significant changes are proposed for the site, appropriate project design, construction, and maintenance can minimize the site sheet flooding potential. 3.4.3 Site Acceleration and Seismic Coefficients Site Acceleration: The potential intensity of ground motion may be estimated by the horizontal peak ground acceleration (PGA), measured in "g" forces. Included in Table 1 are deterministic estimates of site acceleration from possible earthquakes at nearby faults. Ground motions are dependent primarily on the earthquake magnitude and distance to the seismogenic (rupture) zone. Accelerations also are dependent upon attenuation by rock and soil deposits, direction of rupture, and type of fault. For these reasons, ground motions may vary considerably in the same general area. This variability can be expressed statistically by a standard deviation about a mean relationship. The PGA alone is an inconsistent scaling factor to compare to the CBC Z factor and is generally a poor indicator of potential structural damage during an earthquake. Important factors influencing the structural performance are the duration and frequency of strong ground motion, local subsurface conditions, soil -structure interaction, and structural details. Because of these factors, an effective peak acceleration (EPA) is used in structural design. The following table provides the probabilistic estimate of the PGA and EPA taken from the 2002 CGS/USGS seismic hazard maps. EARTH SYSTEMS SOUTHWEST August 11, 2003 - 8 - Estimate of PGA and EPA from 2002 CGS/USGS Prnhnhilictir g0kMiV Hazard Mane File No.: 09285-01 03-07-830 Risk Equivalent Return Period (years) I PGA (g) I Approximate EPA (g)' 10% exceedance in 50years 475 1 0.57 0.51 Notes: 1. Based on a soft rock site, SB/c and soil amplification factor of 1.0 for Soil Profile Type SD. 2. Spectral acceleration (SA) at period of 0.2 seconds divided by 2.5 for 5% damping, as defined by the International Building Code 2001 CBC (1997 UBC) Seismic Coefficients: The California Building Code (CBC) seismic design criteria are based on a Design Basis Earthquake (DBE) that has an earthquake ground motion with a 10% probability of occurrence in 50 years. The PGA and EPA estimates given above are provided for information on the seismic risk inherent in the CBC design. The seismic and site coefficients given in Chapter 16 of the 2001 California Building Code are provided below. 2001 CBC Seismic Coefficients for Chapter 16 Seismic Provisions Seismic Zone: 4 Seismic Zone Factor, Z: 0.4 Soil Profile Type: SD Seismic Source Type: A Closest Distance to Known Seismic Source 8.6 km = 5.4 miles Near Source Factor, Na: Near Source Factor, Nv: Seismic Coefficient, Ca: Seismic Coefficient, Cv: .,1-05 3L1. 0.46 = 0.44Na 0.84 = 0.64Nv Reference Figure 16-2 Table 16-I Table 16-J Table 16-U (San Andreas Fault - Southern) Table 16-S Table 16-T Table 16-Q 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 City of La Quinta General Plan. Riverside County has not been mapped by the California Seismic Hazard Mapping Act (Ca. PRC 2690 to 2699). EARTH SYSTEMS SOUTHWEST August 11, 2003 - 9 - File No.: 09285-01 03-07-830 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 and about 8.6 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. ➢ Existing fill was encountered in our borings to a depth of approximately five feet and was found to be- in a loose to medium dense condition and is unsuitable in its present condition to support structures, fill, and hardscape. This material requires removal and recompaction. The depth of removal of this material is dependent upon the actual depth of the fill encountered during grading. Soils can be readily excavated by normal grading equipment. ➢ Supplemental evaluation and recommendations may be necessary once a final grading plan, building locations, and construction type have been determined. EARTH SYSTEMS SOUTHWEST August 11, 2003 - 10- File No.: 09285-01 03-07-830 ➢ Earth Systems Southwest (ESSW) should provide geotechnical engineering services during project design, site development, excavation, grading, and foundation construction phases of the work. This is to observe compliance with the design concepts, specifications, and recommendations, and to allow design changes in the event that subsurface conditions differ from those anticipated prior to the start of construction. ➢ Plans and specifications should be provided to ESSW prior to grading. Plans should include the grading plans, foundation plans, and foundation details. Preferably, structural loads should be shown on the foundation plans. EARTH SYSTEMS SOUTHWEST August 11, 2003 - 11 - File No.: 09285-01 03-07-830 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 bottom of excavations before placing fill. Local variations in soil conditions may warrant increasing the depth of recompaction and over -excavation. Clearing and Grubbing: At the start of site grading existing vegetation, trees, large roots, pavements, foundations, non -engineered fill, construction debris, trash, and abandoned underground utilities should be removed from the proposed building, structural, and pavement areas. The surface should be stripped of organic growth and removed from the construction area. Areas disturbed during 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). Site Grading: Precise grading plans and structural loads were not available as of the writing of this report. Therefore, general grading criteria are being provided herein to enable the owner to make an informed decision with regards to site development. Because of the relatively non- uniform and unconsolidated nature of the majority of the site soils, we recommend in general the upper 3 feet below existing grade or 2 feet below the bottom of the deepest footing, whichever is greater, should be removed and recompacted within the building pads and other settlement prone structures. The removal area should extend 5 feet from the outside edge of the exterior footings of the proposed structures. In addition, the bottom of the excavations should be moisture conditioned, scarified and recompacted to increase the relative compaction of the native soils within the influence of the building pads and other settlement prone structures. The depth of proposed cuts and fills and type of construction will influence the actual depth of over - excavation, and the effectiveness of the pre -moistening program. Once precise grading plans are available, supplemental recommendations should be provided. However, for purposes of this report we are assuming column loads of up to 100kips and continuous wall loading of up to 3 kips per lineal foot. Therefore, the depth of moisture penetration should extend to a depth of at least 5 feet below the bottom of the over -excavation. The resulting surface should be processed using heavy vibratory type equipment to effectively densify the soil to a depth of 3 to 4 feet below the bottom of the over -excavation. Auxiliary Structures Subgrade Preparation: Auxiliary structures such as landscape or retaining walls should have the foundation subgrade prepared similar to the building pad recommendations given above. The lateral extent of the over -excavation needs only to extend 2 feet beyond the face of the footing. EARTH SYSTEMS SOUTHWEST August 11, 2003 - 12 - File No.: 09285-01 03-07-830 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 3 -foot below finished subgrades. Compaction should be verified by testing. Engineered Fill Soils: Both the existing fill and native soil is suitable for use as engineered fill and utility trench backfill provided it is free of significant organic or deleterious matter. Soils 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. 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 evaluate the import fill soils before hauling to the site. However, because of the potential variations within the borrow source, import soil will not be prequalified by ESSW. The imported fill should be placed in lifts no greater than 8 inches in loose thickness and compacted to at least 90% relative compaction (ASTM D 1557) near optimum moisture content. Shrinkage: The shrinkage factor for earthwork is expected to range from 15 to 25 percent for the upper excavated or scarified site soils. This estimate is based on compactive effort to achieve an average relative compaction of about 92% and may vary with contractor methods. Subsidence is estimated to 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 CalOSHA requirements. Our site exploration and knowledge of the general area indicates there is a potential for caving of site excavations (utilities, footings, etc.). Excavations within sandy soil should be kept moist, but not saturated, to reduce the potential of caving or sloughing. Where excavations over 4 feet deep are planned, lateral bracing or appropriate cut slopes of 1.5:1 (horizontal: vertical) should be provided. No surcharge loads from stockpiled soils or construction materials should be allowed within a horizontal distance measured from the top of the excavation slope, equal to the depth of the excavation. Utility Trenches: Backfill of utilities within road or public right-of-ways should be placed in conformance with the requirements of the governing agency (water district, public works department, etc.) Utility trench backfill within private property should be placed in conformance with the provisions of this report. In general, service lines extending inside of property may be EARTH SYSTEMS SOUTHWEST August 11, 2003 -13 - File No.: 09285-01 03-07-830 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 (if any) 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. 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). ➢ Continuous wall foundations, 12 -inch minimum width and 12 inches below grade: 1500 psf for dead plus design live loads Allowable increases of 300 psf per each foot of additional footing width and 300 psf for each additional 0.5 foot of footing depth may be used up to a maximum value of 3000 psf. ➢ Isolated pad foundations, 2 x 2 foot minimum in plan and 18 inches below grade: 2000 psf for dead plus design live loads Allowable increases of,2Wpsf per each foot of additional footing width and 400 psf for each additional 0.5 foot of footing -depth may be used up to a maximum value of 3000 psf. A one-third ('/3) increase in the bearing pressure may be used when calculating resistance to wind or seismic loads. The allowable bearing values indicated are based on the anticipated maximum loads stated in Section 1.1 of this report. If the anticipated loads exceed these values, the geotechnical engineer must reevaluate the allowable bearing values and the grading requirements. EARTH SYSTEMS SOUTHWEST August 11, 2003 -14- File No.: 09285-01 03-07-830 Minimum reinforcement for continuous wall footings should be two, No. 4 steel reinforcing bars, one placed near the top and one placed near the bottom of the footing. This reinforcing is not intended to supersede any structural requirements provided by the structural engineer. Expected Settlement: Estimated total static settlement should be less than 1 inch, based on footings founded on firm soils as recommended. Differential settlement between exterior and interior bearing members should be less than '/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 0.35 of dead load may be used. An allowable passive equivalent fluid pressure of 250 pcf may also be used. These values include a factor of safety of 1.5. Passive resistance and frictional resistance may be used in combination if the friction coefficient is reduced 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 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 moisture retarder) 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 before placing the concrete. Low -slump concrete should be used to help reduce the potential for concrete shrinkage. The effectiveness of the moisture retarder is dependent upon its quality, method of overlapping, its protection during construction, and the successful sealing of the retarder around utility lines. Slab thickness and reinforcement: Slab thickness and reinforcement of slabs -on -grade are contingent on the recommendations of the structural engineer or architect and the expansion index of the supporting soil. Based upon our findings, a modulus of subgrade reaction of approximately 200 pounds per cubic inch can be used in concrete slab design for the expected very low expansion subgrade. Concrete slabs and flatwork should be a minimum of 4 inches thick�(actual, not nominal). We suggest that the concrete slabs be reinforced with a minimum of No. 3rebars 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. EARTH SYSTEMS SOUTHWEST August 11, 2003 - 15 - File No.: 09285-01 03-07-830 Control Joints: Control joints should be provided in all concrete slabs -on -grade at a maximum spacing of 36 times the slab thickness (12 feet maximum on -center, each way) as recommended by American Concrete Institute (ACI) guidelines. All joints should form approximately square patterns to reduce the potential for randomly oriented, contraction cracks. Contraction joints in the slabs should be tooled at the time of the pour or saw cut ('/4 of slab depth) within 8 hours of concrete placement. Construction (cold) joints should consist of thickened butt joints with one- half inch dowels at 18 -inches on center or a thickened keyed joint to resist vertical deflection at the joint. All construction joints in exterior flatwork should be sealed to reduce the potential of moisture or foreign material intrusion. These procedures will reduce the potential for randomly oriented cracks, but may not prevent them from occurring. Curingand 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 effected by temperature, wind, and humidity. Quality control procedures may be used including trial batch mix designs, batch plant inspection, and on-site special inspection and testing. Typically, for this type of construction and using 2500 -psi concrete, many of these quality control procedures are not required. 5.6 Mitigation of Soil Corrosivity on Concrete Selected chemical analyses for corrosivity were conducted on soil samples from the project site as shown in Appendix B. The native soils were found to have a sulfate ion concentration of 49 ppm, however test results on soils in the vicinity of the site indicate moderate sulfate content, Chloride ion concentration of 91 ppm. Sulfate ions can attack the cementitious material in concrete, causing weakening of the cement matrix and eventual deterioration by raveling. Chloride ions can cause corrosion of reinforcing steel. The California Building Code requires for moderate sulfate conditions that Type V Portland cement be used with a maximum water/cement ratio of 0.50 using a 4000 -psi concrete mix (CBC Table 19-A-4). A minimum concrete cover of three (3) inches should be provided around steel reinforcing or embedded components exposed to native soil or landscape water. Additionally, the concrete should be thoroughly vibrated during placement. Electrical resistivity testing of the soil suggests that the site soils may present a severe 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. Earth Systems does not practice corrosion engineering. We recommend that a qualified corrosion engineer evaluate the corrosion potential on metal construction materials and concrete at the site to provide mitigation of corrosive effects. 5.7 Pavements Since no traffic loading were provided by the design engineer or owner, we have assumed traffic loading for comparative evaluation. The design engineer or owner should decide the appropriate traffic conditions for the pavements. Maintenance of proper drainage and periodic sealing is EARTH SYSTEMS SOUTHWEST August 11, 2003 -16- File No.: 09285-01 03-07-830 advised to prolong the service life of the pavements. Water should not pond on or near paved areas. The following table provides our preliminary recommendations for pavement sections. Final pavement sections recommendations should be based on design traffic indices and R -value tests conducted during grading after actual subgrade soils are exposed. PRELIMINARY RECOMMENDED PAVEMENTS SECTIONS R -Value Subgrade Soils - 30 (assumed) Design Method — CAT.TRANS 1995 Notes: 1. Asphaltic concrete should be Caltrans, Type B, '/2 -in. or '/4 -in. maximum -medium grading and compacted to a minimum of 95% of the 75 -blow Marshall density (ASTM D 1559) or equivalent. 2. Aggregate base should be Caltrans Class 2 (3/4 in. maximum) and compacted to a minimum of 95% of ASTM D1557 maximum dry density near its optimum moisture. 3. All pavements should be placed on 12 inches of moisture -conditioned subgrade, compacted to a minimum of 90% of ASTM D 1557 maximum dry density near its optimum moisture. 4. Portland cement concrete should have a minimum of 3250 psi compressive strength @ 28 days. 5. Equivalent Standard Specifications for Public Works Construction (Greenbook) may be used instead of Caltrans specifications for asphaltic concrete and aggregate base. EARTH SYSTEMS SOUTHWEST Flexible Pavements Rigid Pavements Asphaltic Aggregate Portland Aggregate Traffic Concrete Base Cement Base Index Pavement Use Thickness Thickness Concrete Thickness (Assumed) (Inches) (Inches) I (Inches) (Inches) 4.0 Auto Parking Areas 3.0 4.0 4.0 4.0 Lightly Loaded Drive 5.0 Lanes 3.0 5.5 5.0 4.0 7.0 Truck Lanes 4.0 9.5 6.0 6.0 Notes: 1. Asphaltic concrete should be Caltrans, Type B, '/2 -in. or '/4 -in. maximum -medium grading and compacted to a minimum of 95% of the 75 -blow Marshall density (ASTM D 1559) or equivalent. 2. Aggregate base should be Caltrans Class 2 (3/4 in. maximum) and compacted to a minimum of 95% of ASTM D1557 maximum dry density near its optimum moisture. 3. All pavements should be placed on 12 inches of moisture -conditioned subgrade, compacted to a minimum of 90% of ASTM D 1557 maximum dry density near its optimum moisture. 4. Portland cement concrete should have a minimum of 3250 psi compressive strength @ 28 days. 5. Equivalent Standard Specifications for Public Works Construction (Greenbook) may be used instead of Caltrans specifications for asphaltic concrete and aggregate base. EARTH SYSTEMS SOUTHWEST August 11, 2003 - 17- File No.: 09285-01 A051#f)IW4 03-07-830 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 rev1q.W nand -should n� otbe relied upon.after,aTperiod,of one year. In the event that any changes in the nature, design, or location of structures are planned, the conclusions and recommendations contained in this report shall not be considered valid unless the changes are reviewed and conclusions of this report are modified or verified in writing. This report is issued with the understanding that the owner, or the owner's representative, has the responsibility to bring the information and recommendations contained herein to the attention of the architect and engineers for the project so that they are incorporated into the plans and specifications for the project. The owner, or the owner's representative, also has the responsibility to verify that the general contractor and all subcontractors follow such recommendations. It is further understood that the owner or the owner's representative is responsible for submittal of this report to the appropriate governing agencies. As the Geotechnical Engineer of Record for this project, Earth Systems Southwest (ESSW) has striven to provide our services in accordance with generally accepted geotechnical engineering practices in this locality at this time. No warranty or guarantee is express or implied. This report was prepared for the exclusive use of the Client and the Client's authorized agents. ESSW should be provided thpportunity for general review of final design and specifications in order that earthwork and foundation recommendations may be properly rote retell d implemented in the design and specifications. If ESSW-is not accorded the privilege of making this �recommended�review, we can assume' no responsibility for misinterpretation of our recommendations. Although available through ESSW, the current scope of our services does not include an environmental assessment, or investigation for the presence or absence of wetlands, hazardous or EARTH SYSTEMS SOUTHWEST August 11, 2003 - 18 - File No.: 09285-01 03-07-830 toxic materials in the soil, surface water, groundwater or air on, below, or adjacent to the subject property. 6.2 Additional Services This report is based on the assumption that an adequate program of client consultation, construction monitoring, and testing will be performed during the final design and construction phases to check compliance with these recommendations. Maintaining ESSW as the geotechnical consultant from beginning to end of the project will provide continuity of services. The geotechnical engineering firm providing tests and observations shall assume the responsibility of Geotechnical Engineer of Record. Construction monitoring and testing would be additional services provided by our firm. The costs of these services are not included in our present fee arrangements, but can be obtained from our office. The recommended review, tests, and observations include, but are not necessarily limited to the following: • Consultation during the final design stages of the project. • Review of the building and to observe that recommendations of our report • Observation and testing during site preparation, grading and placement of engineered fill s required by CBC (UBC) Sections 1701 and 3j4-1-671 6Mgrading ordinances. • Consultation as needed during construction. •. - rw - nF '^.11]M9RWip�tl.�.�l+RR.+.� MR��`J�'+.:.�*!k'�LItMkRR'!1!gptl.'.Fd .Y'. 1 Appendices as cited are attached and complete this report. EARTH SYSTEMS SOUTHWEST August 11, 2003 - 19 - File No.: 09285-01 03-07-830 REFERENCES Abrahamson, N., and Shedlock, K., editors, 1997, Ground motion attenuation relationships: Seismological Research Letters, v. 68, no. 1, January 1997 special issue, 256 p. American Concrete Institute (ACI), 1996, ACI Manual of Concrete Practice, Parts 1 through 5. California Geologic Survey (CGS), 1997, Guidelines for Evaluating and Mitigating Seismic Hazards in California, Special Publication 117. Cao, T, Bryant, W.A., Rowhandel, B., Branum. D., and Wills, C., 2003, The Revised 2002 California Probabilistic Seismic Hazard Maps, California Geologic Survey (CGS), June 2003. California Department of Water Resources, 1964, Coachella Valley Investigation, Bulletin No. 108, 146 pp. Envicom Corporation and the County of Riverside Planning Department, 1976, Seismic Safety and Safety General Plan Elements Technical Report, County of Riverside. Frankel, A.D., et. al, 2002, Documentation for the 2002 Update of the National Seismic Hazard Maps, USGS Open -File Report 02-420. Hart, E.W., 1997, Fault -Rupture Hazard Zones in California: California Division of Mines and Geology Special Publication 42. International Code Council (ICC), 2002, California Building Code, 2001 Edition. International Code Council (ICC), 2003, International Building Code, 2003 Edition. Jennings, CW, 1994, Fault Activity Map of California and Adjacent Areas: California Division of Mines and Geology, Geological Data Map No. 6, scale 1:750,000. Petersen, M.D., Bryant, W.A., Cramer, C.H., Cao, T., Reichle, M.S., Frankel, A.D., Leinkaemper, J.J., McCrory, P.A., and Schwarz, D.P., 1996, Probabilistic Seismic Hazard Assessment for the State of California: California Division of Mines and Geology Open -File Report 96-08. Reichard, E.G. and Mead, J.K., 1991, Evaluation of a Groundwater Flow and Transport Model of the Upper Coachella Valley, California, U.S.G.S. Open -File Report 91-4142. Rogers, T.H., 1966, Geologic Map of California - Santa Ana Sheet, California Division of Mines and Geology Regional Map Series, scale 1:250,000. Tokimatsu, K, and Seed, H.B., 1987, Evaluation of Settlements in Sands Due To Earthquake Shaking, ASCE, Journal of Geotechnical Engineering, Vol. 113, No. 8, August 1987. Working Group on California Earthquake Probabilities, 1995, Seismic Hazards in Southern California: Probable Earthquakes, 1994-2024: Bulletin of the Seismological Society of America, Vol. 85, No. 2, pp. 379-439. Wallace, R. E., 1990, The San Andreas Fault System, California: U.S. Geological Survey Professional Paper 1515, 283 p. EARTH SYSTEMS SOUTHWEST APPENDIX A Site Location Map Boring Location Map Table 1 Fault Parameters Logs of Borings EARTH SYSTEMS SOUTHWEST a lFRslgT F 10 R FFwgY Fred Waring Dr. Miles Ave. H N y C O Cf H C NOT TO SCALE fi �p Q dl Corp�rafe C ehtre 3 Or E d� Z c� N SITE 3 0 Figure 1 - Site Location Map Corporate Center Professional Plaza Lot 6 & 7 Parcel Map 29351 Commerce Court & Corporate Centre Dr. La Quinta, California File Number 09285-01 I Earth Systems '..�� Southwest .-_~- CORP RA re CeAf 1 _rR F PARKING AREA r. v i i PARKING AREA W �1.. FB- B-3 LEGEND B4 APPROXIMATE LOCATION OF BORING Z I 1 i 0 20ft u SCALE Figure 2 - Boring Location Ma Corporate Center Professional Plaza Lot 6 & 7 Parcel Map 29351 Commerce Court & Corporate Centre Dr La Quinta, California File Number: 09285-01 Earth Systems Southwest Lots 6 & 7, Corporate Centre Professional Plaza, LQ, CA 09285-01 Table 1 Fault Parameters & & Deterministic Estimates of Mean Peak Ground Acceleration (PGA) Fault Name or Seismic Zone Distance from Site (mi) (krn) 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 5.4 8.6 SS A 7.7 24 220 199 0.49 San Andreas - Mission Crk. Branch 5.6 9.0 SS A 7.1 25 220 95 0.40 San Andreas - Banning Branch 5.6 9.0 SS A 7.1 10 220 98 0.40 Burnt Mtn. 17.1 27.5 SS B 6.5 0.6 5000 21 0.12 Eureka Peak 18.0 29.0 SS B 6.4 0.6 5000 19 0.11 San Jacinto-Anza 21.7 34.9 SS A 7.2 12 250 91 0.15 San Jacinto -Coyote Creek 21.9 35.3 SS B 6.8 4 175 41 0.12 Pinto Mountain 30.0 48.3 SS B 7.2 2.5 499 74 0.11 Emerson So. - Copper Mtn. 31.4 50.5 SS B 7.0 0.6 5000 54 0.09 Landers 32.2 51.8 SS B 7.3 0.6 5000 83 0.11 Pisgah -Bullion Mtn. -Mesquite Lk 33.5 53.9 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 36.5 58.8 SS B 6.9 12 83 43 0.07 North Frontal Fault Zone (East) 38.4 61.7 DS B 6.7 0.5 1727 27 0.07 Earthquake Valley 40.4 65.0 SS B 6.5 2 351 20 0.05 Brawley Seismic Zone 41.5 66.9 SS B 6.4 25 24 42 0.05 Johnson Valley (Northern) 43.0 69.2 SS B 6.7 0.6 5000 35 0.05 Elsinore -Julian 44.4 71.4 SS A 7.1 5 340 76 0.07 Calico - Hidalgo 44.7 72.0 SS B 7.3 0.6 5000 95 0.08 Elsinore -Temecula 47.9 77.2 SS B 6.8 5 240 43 0.05 Lenwood-Lockhart-Old Woman Sprgs 48.8 78.5 SS B 7.5 0.6 5000 145 0.08 North Frontal Fault Zone (West) 49.5 79.6 DS B 7.2 1 1314 50 0.08 Elmore Ranch 49.7 80.0 SS B 6.6 1 225 29 0.04 Elsinore -Coyote Mountain 51.7 83.1 SS B 6.8 4 625 39 0.05 Superstition Mtn. (San Jacinto) 53.7 86.4 SS B 6.6 5 500 24 0.04 Superstition Hills (San Jacinto) 54.5 87.8 SS B 6.6 4 250 23 0.04 Helendale - S. Lockhardt 56.7 91.2 SS B 7.3 0.6 5000 97 0.06 San Jacinto -San Bernardino 58.7 94.5 SS B 6.7 12 100 36 0.04 Elsinore -Glen Ivy 61.4 98.8 SS B 6.8 5 340 36 0.04 Notes: 1. Jennings (1994) and California Geologic Survey (CGS) (2003) 2. CGS (2003), SS = Strike -Slip, DS = Dip Slip, BT = Blind Thrust 3. 2001 CBC, where Type A faults: Mmax > 7 & slip rate >5 mm/yr & Type C faults: Mmax <6.5 & slip rate < 2 mm/yr 4. CGS (2003) 5. The estimates of the mean Site PGA are based on the following attenuation relationships: Average of. (1) 1997 Boore, Joyner & Fumal; (2) 1997 Sadigh et al; (3) 1997 Campbell, (4) 1997 Abrahamson & Silva (mean plus sigma values are about 1.5 to 1.6 times higher) Based on Site Coordinates: 33.710 N Latitude, 116.282 W Longtude and Site Soil Type D EARTH SYSTEMS SOUTHWEST Earth Systems Southwest 79-811 B Country Club Drive, Bermuda Dunes, CA 92201 Phone (760) 345-1588 FAX (760) 345-7315 Boring No: B-1 Drilling Date: July 1, 2003 Project Name: Lots 6 & 7, Corporate Center Prof. Plaza, La Quinta, CA Drilling Method: 8" Hollow Stem Auger File Number: 09285-01 Drill Type: CME 45 w/ Rope & Cathead Boring Location: See Figure 2 13,21,33 Logged By: Karl A. Harmon v Sample Type Penetration c SAND WITH SILT: light olive gray, dry to damp, Description of Units Page I of 1 a w Resistance E 0 CIO The q 0 •o Note: stratification lines shown represent the Y F- p � o approximate boundary between soil and/or rock types Graphic Trend Q 7 (Blows/6") O U and the transition may be gradational. Blow Count Dry Density 5 10 15 20 25 30 35 40 45 50 55 60 SM SILTY SAND: light olive, medium dense, damp, 13,21,33 104 2 fine to very fine grained SP -SM SAND WITH SILT: light olive gray, dry to damp, 8,12,15 108 3 fine grained, thin layer of thin visqueen 5,7,12 light olive brown, damp SM SILTY SAND: olive, medium dense, damp to moist, fine grained, some sand with silt 5,6,7 SP -SM SAND WITH SILT: pale olive, medium dense, 8 9 4 damp, fine grained, some sand Boring completed at 21.5 feet No Groundwater or Bedrock Encountered Earth Systems Southwest 79-811B Country Club Drive, Bermuda Dunes, CA 92201 5 10 15 20 25 30 35 40 45 50 55 60 rnonet/ov)wD-1:)55 YAAk/OV)_ :)-l.11J Boring No: B-2 SM 108 101 7 3 Drilling Date: July 1, 2003 Project Name: Lots 6 & 7, Corporate Center Prof. Plaza, La Quinta, CA Drilling Method: 8" Hollow Stem Auger File Number: 09285-01 SAND WITH SILT: yellowish gray, light olive Drill Type: CME 45 w/ Rope & Cathead Boring Location: See Figure 2 Logged By: Karl A. Harmon gray, damp, fine grained Sample Type Penetration — a °�''� Description of Units IPage I of 1 A u Resistance E U q ¢ •o Y Note: The stratification lines shown represent the q Y p (Blows/6") v� q ��- ° o approximate boundary between soil and/or rock types Graphic Trend M q U and the transition may be gradational. Blow Count Dry Density 5 10 15 20 25 30 35 40 45 50 55 60 26,50/5" 13,19,28 SM 108 101 7 3 SILTY SAND: pale olive, very dense, damp, fine grained, some SP -SM (FILL), first attempt to sample -refusal > 50/6" on buried AC SP -SM SAND WITH SILT: yellowish gray, light olive gray, damp, fine grained 5,5,7 light olive gray 6,7,9 dusky ellow, some fine to medium grained sand Boring completed at 19 feet No Groundwater or Bedrock Encountered Earth Systems ORI Southwest 5 10 15 20 25 -30 35 40 45 50 55 60 18,32,50/5" 12,15,19 79-811B Country Club Drive, Bermuda Dunes, CA 92201 Phone (760) 345-1588 FAX (760) 345-7315 SM Boring No: B-3 3 4 SILTY SAND: light olive gray, very dense, damp, fine grained, some sand with silt olive, medium dense, moist, lenses of moist to wet silt, lenses of sand with silt Drilling Date: July 1, 2003 Project Name: Lots 6 & 7, Corporate Center Prof. Plaza, La Quinta, CA Drilling Method: 8" Hollow Stem Auger File Number: 09285-01 Drill Type: CME 45 w/ Rope & Cathead medium dense, dry to damp, fine grained Boring Location: See Figure 2 Logged By: Karl A. Harmon Sample Type Penetration medium dense, damp, fine to very fine grained C Description of Units Pagel of] Boring completed at 16.5 feet � 3' Resistance 0 q a • n Note: The stratification lines shown represent the q0 o (Blows/6") rn o approximate boundary between soil and/or rock types Graphic Trend No Groundwater or Bedrock Encountered M G] U and the transition ma be radational. Y S Blow Count Dry Density 5 10 15 20 25 -30 35 40 45 50 55 60 18,32,50/5" 12,15,19 SM 107 112 3 4 SILTY SAND: light olive gray, very dense, damp, fine grained, some sand with silt olive, medium dense, moist, lenses of moist to wet silt, lenses of sand with silt SP -SM SAND WITH SILT: light olive gray, loose to 4,4,6 medium dense, dry to damp, fine grained 5,7,8 medium dense, damp, fine to very fine grained Boring completed at 16.5 feet No Groundwater or Bedrock Encountered Earth Systems Southwest 5 10 15 20 25 30 35 40 45 50 55 60 ' 79-81113 Country Club Drive, Bermuda Dunes, CA 92201 Phone (760) 345-1588 FAX (760) 345-7315 1. t Boring No: B-4 104 102 g 6 SILTY SAND: olive, medium dense, dry to damp, fine grained, some sand with silt moist lenses of sand with silt and chunks of charcoal Drilling Date: July 1, 2003 Project Name: Lots 6 & 7, Corporate Center Prof. Plaza, La Quinta, CA Drilling Method: 8" Hollow Stem Auger File Number: B-4 11,12,17 Drill Type: CME 45 w/ Rope & Cathead loo Boring Location: See Figure 2 fine grained Logged By: Karl A. Harmon Sample Type Type,., Penetration yellowish gray, damp, some sand with silt DCSCrIpiIOII Of Units Page 1 of 1 Resistance a E V) U r -q q o a� •o : Note: The stratification lines shown represent the pale olive/dusky yellow, dry to damp q y p (Blows/6") v� - o° approximate boundary between soil and/or rock types Graphic Trend m q U and the transition may be gradational. Blow Count Dry Density 5 10 15 20 25 30 35 40 45 50 55 60 ' 11,19,35 11,16,30 1. t SM 104 102 g 6 SILTY SAND: olive, medium dense, dry to damp, fine grained, some sand with silt moist lenses of sand with silt and chunks of charcoal SP -SM SAND WITH SILT: light olive gray, damp to moist, 11,12,17 loo 3 fine grained 7,12,17 yellowish gray, damp, some sand with silt 5,6,8 pale olive/dusky yellow, dry to damp 5,6,9 medium dense, fine to very fine grained 9,11,14 13,18,26 dry Boring completed at 51.5 feet No Groundwater or Bedrock Encountered APPENDIX B Laboratory Test Results File No.: 09285-01 August 11, 2003 UNIT DENSITIES AND MOISTURE CONTENT ASTM D2937 & D2216 Job Name: Corporate Center Professional Plaza B1 Unit Moisture USCS Sample Depth Dry Content Group Location (feet) Density (pcf) N Symbol B1 2.5 104 2 SP -SM BI 5 108 3 SP -SM B2 2.5 108 7 SP -SM B2 7.5 101 3 SP -SM B3 2 107 3 SM B3 5 112 4 SM B4 2 104 8 SM B4 5 102 6 SM B4 10 100 3 SP -SM EARTH SYSTEMS SOUTHWEST File No.: 09285-01 Job Name: Corporate Center Professional Plaza August 11, 2003 AMOUNT PASSING NO. 200 SIEVE ASTM D 1140 B 1 10 9 SP -SM B2 12.5 11 SP -SM EARTH SYSTEMS SOUTHWEST Fines USCS Sample Depth Content Group Location (feet) (%) Symbol B 1 10 9 SP -SM B2 12.5 11 SP -SM EARTH SYSTEMS SOUTHWEST August 11, 2003 ASTM D-422 #16 99 File No.: 09285-01 #30 PARTICLE SIZE ANALYSIS Job Name: Corporate Center Professional Plaza Sample ID: B1 @ 1-4' Feet Description: Silty Sand: F w/ Trace Gravel (SM) Sieve Percent Size Passing 1-1 /2" 100 1" 100 3/4" 100 1/2" 99 3/8" 99 #4 99 #8 99 August 11, 2003 ASTM D-422 #16 99 % Gravel: 1 #30 99 % Sand: 72 #50 91 % Silt: 20 #100 58 % Clay (3 micron): 8 #200 28 (Clay content by short hydrometer method) 100 90 80 70 on 60 .N N cC 50 c ILIU L p- 40 30 20 10 0 100 10 1 Particle Size( mmq.1 0.01 0.001 EARTH SYSTEMS SOUTHWEST File No.: 09285-01 August 11, 2003 CONSOLIDATION TEST ASTM D 2435 & D 5333 Corporate Center Professional Plaza B I @ 5' Feet Sand: F (SP -SM) Ring Sample Initial Dry Density: 91.9 pcf Initial Moisture, %: 2.6% Specific Gravity (assumed): 2.67 Initial Void Ratio: 0.813 Hydrocollapse: 1.2% @ 2.0 ksf % Change in Height vs Normal Presssure Diagram 8 Before Saturation Hydrocollapse 0 After Saturation -Rebound 2- 0- -2 - -3 - 4- -5 i7 i V U o -6 - a. -7 - -8 -9 -10 -12 0.1 Vertical Effective Stress, ksf 10.0 EARTH SYSTEMS SOUTHWEST I 1 File No.: 09285-01 August 11, 2003 CONSOLIDATION TEST ASTM D 2435 & D 5333 Corporate Center Professional Plaza B3 @ 5' Feet Sand: F (SM) Ring Sample Initial Dry Density: 100.0 pcf Initial Moisture, %: 3.9% Specific Gravity (assumed): 2.67 Initial Void Ratio: 0.666 Hydrocollapse: 1.8% @ 2.0 ksf EARTH SYSTEMS SOUTHWEST File No.: 09285-01 SOIL CHEMICAL ANALYSES Job Name: Corporate Center Professional Plaza Job No.: 09285-01 Sample ID: B-1 Sample Depth, feet: 1-4' pH: 6.6 Resistivity (ohm -cm): 1,213 (saturated soil) Chloride (Cl), ppm: 91 Sulfate (SOA ppm: 49 Note: Tests performed by Subcontract Laboratory: KEANTAN LABORATORIES 720 North Valley, Suite B Anaheim, CA 92801 Tel.: (714) 535-7616 General Guidelines for Soil Corrosivitv August 11, 2003 Chemical Agent Amount in Soil Degree of Corrosivity Soluble 0-1000 ppm Low Sulfates 1000-2000 ppm Moderate 2000-5000 ppm Severe > 5000 ppm Very Severe Resistivity 1-1000 ohm -cm Very Severe 1000-2000 ohm -cm Severe 2000-10,000 ohm -cm Moderate 10,000+ ohm -cm Low EARTH SYSTEMS SOUTHWEST