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0103-049 (CSCS) Geotechnical Engineering Report1 1 1 Earth Systems Southwest CITY OF LA QUINTA BUILDING & SAFEY DEPT. APPROVED FOR -CONSTRUCTION Consulting Engineers and Geologists MADISON DEVELOPMENT 938 NORTH MOUNTAIN AVENUE ONTARIO, CALIFORNIA 91762 REPORT OF TESTING AND OBSERVATION DURING GRADING OF POINT HAPPY LA QUINTA, CALIFORNIA File No.: 07074-02 01-02-753 0Earth Systems "`i Southwest February 20, 2001 Madison Development 938 North Mountain Avenue Ontario, California 91672 Attention: Mr. Ed Alderson Project: Point Happy La Quinta, California Subject: Report of Testing and Observations Performed During Grading 79-811 B Country Club Drive Bermuda Dunes, CA 92201 (760)345-1588 (800)924-7015 FAX (760) 345-7315 File No.: 07074-02 01-02-753 Reference: Geotechnical Engineering Report, prepared by Earth Systems Consultants Southwest, dated March 8, 1999; Revised March 24, 1999; Report No.: 99-03-759 Submitted herewith is a .report of testing and intermittent observations performed during the grading on the above referenced project. Grading operations were performed by F & F Grading, using conventional heavy equipment. Testing was performed as per authorization of Mr..Ed Alderson. Test results are presented on the attached test report sheet with their estimated locations plotted on the accompanying plan. Compaction tests were performed in accordance with ASTM D 2922-81, Method A or B, and ASTM D 3017-88 Nuclear Density Test Procedures. Maximum Density -Optimum Moisture were determined in the laboratory in accordance with ASTM D 1557 -91, -Method A or C. Test results are as follows: Soil Description USCS Maximum Density Optimum Moisture Olive brown silty Sand, fine to coarse grained SM 119.0 pcf 10.5% DISCUSSION: 1. The project is located on the northwest corner of Highway 111 and Washington Street in the City of La Quinta, California. 2. Prior to grading, the site consisted of vacant desert lands with sparse vegetation February 20, 2001 - 2 - File No.: 07074-02 01-02-753 ' 3. The proposed development consists of 9 commercial structures with a combination of wood and steel frame with a stucco coating. r4. The scope of our work was based on the plans and staking by others. ' 5. The site was cleared of pre-existing vegetation and pre -watered to help control dust. 6. The building pads were over excavated to a depth of 3 feet below pad grade. The exposed surface was moisture conditioned and compacted. 7 Fill materials consisting of previously removed soils and other site soils were placed in relatively thin lifts and compacted into place. . 8. A total of 42 compaction p on tests were performed. ' 9. Test results indicate that a minimum of 90% of maximum dry density has been obtained in the areas tested. ' 10. The test locations are approximate and are determined by pacing and sighting from prominent field features. In our work, we have relied on topographic and survey ' information provided by others. 11. Based upon intermittent ermittent observations and testing during the grading operations, on January 5 through February 16, 2001 on this project, it is our opinion that the grading is ' essentially in conformance with recommendations of the referenced geotechnical engineering report, as well as the grading ordinances of the City of La Quinta. ' 12. As used herein, the term "observation" implies only that we observed the progress of work we agreed to be involved with, and performed test on which together we based our ' opinion as to whether the work essentially complies with job requirements. 13. With any manufactured product, there are statistical variations in its uniformity and in the accuracy of tests used to measure its quality. As compared with other manufactured products, field construction usually presents large statistical variations in its uniformity and accuracy of test results used to measure its quality. Thus, even with very careful ' observation and testing, it cannot be said that all parts of the product comply with the job requirements and the degree of certainty is greater with full-time observation than it is with intermittent observations and testing. Therefore, our opinion based on observing ' and testing the work means that there is only a statistically based, reasonable certainty that the work essentially complies with the job requirements. ' 14. We make no warranty, express or implied, except that our services were performed in accordance with engineering principles generally accepted at this time and location. ' 15. It is recommended that Earth Systems Southwest (ESSW) be provided the opportunity for a general review of any changes to the final design and/or location of the proposed structures in order that earthwork and foundation recommendations may be properly EARTH SYSTEMS SOUTHWEST ' February 20, 2001 -3 - File No.: 07074-02 01-02-753 ' interpreted. If ESSW is not accorded the privilege of making this recommended review, we can assume no responsibility for misinterpretation of our recommendations. 16. This report is issued with the understanding that it is the responsibility of the owner, or of his representative, to insure that the information and recommendations contained herein ' are called to the attention of the architect and engineers for the project and are incorporated into the plans and specifications for the project. It is also the owners' responsibility, or his representative, to ensure that the necessary steps are taken to see that ' the general contractor and all subcontractors carry out such recommendations in the field. It is further understood that the owner or his representative is responsible for submittal of this report to the appropriate governing agencies. If there are any questions concerning this report, please do not hesitate to contact this office. ' Respectfully submitted, EARTH SYSTEMS SOUTHWEST Reviewed b Q 0ESS/Oti S. ' PD G� !co CE 38234 m w EXP. 03/31/05 � Phillip D. Clanton Craig S. Supervisory Technician CE 38234 sr�tFC' FOP�\P OFC Grading/pdc/csh/dac ' Distribution: 2 /Madison Development (Ontario) 4/Madison Development (La Quinta) ' 1NTA File 1/BD File EARTH SYSTEMS SOUTHWEST ' REPORT OF RELATIVE COMPACTIONS JOB NAME: Point Happy LOCATION: La Quinta, California FILE NO.: 07074-02 REPORT NO: 01-02-753 Page 1 of I Test No Date Tested Description Elevation %MoistureDry Density Relative Maximum In Place In Place Compaction Density Grading 1 01/05/01 Per Plan 3.0 BPG 10.5 114.0 96 119.0 2 01/05/01 Per Plan 3.0 BPG 11.2 109.2 92 119.0 3 01/05/01 Per Plan 3.0 BPG 12.7 109.6 92 119.0 4 01/05/01 Per Plan 3.0 BPG 10.7 110.7 93 119.0 5 01/05/01 Per Plan 1.0 BPG 9.8 109.5 92 119.0 6 01/05/01 Per Plan 1.0 BPG 10.2 107.9 91 119.0 7 01/05/01 Per Plan 1.0 BPG 11.2 108.2 91 119.0 8 01/08/01 Per Plan FPG 12.8 114.0 96 119.0 9 01/08/01 Per Plan FPG 11.6 109.2 92 119.0 10 01/08/01 Per Plan 3.0 BPG 10.8 109.2 92 119.0 11 01/08/01 Per Plan 3.0 BPG 10.5 110.5 93 119.0 12 01/08/01 Per Plan 3.0 BPG 12.9 107.1 90 119.0 13 01/08/01 Per Plan 1.0 BPG 13.6 107.5 91 119.0 14 01/08/01 Per Plan FPG 11.7 110.7 93 119.0 15 01/09/01 Per Plan 1.0 BPG 13.6 110.8 93 119.0 -16 01/09/01 Per Plan FPG 12.4 109.7 92 119.0 17- 01/09/01 Per Plan 3.0 BPG 10.9 110.9 93 119.0 18 01/09/01 Per Plan 1.0 BPG 12.8 108.4 91 119.0 19 01/09/01 Per Plan FPG 13.6 109.7 92 119.0 20 01/10/01 Per Plan 3.0 BPG 13.2 110.9 93 119.0 21 01/10/01 Per Plan 3.0 BPG 12.8 110.7 93 119.0 21 01/10/01 Per Plan 3.0 BPG 12.5 109.6 92 119.0 23 01/10/01 Per Plan 3.0 BPG 11.9 107.3 90 119.0 24 01/11/01 Per Plan 1.0 BPG 13.7 110.9 93 119.0 25 01/11/01 Per Plan 1.0 BPG 11.9 110.7 93 119.0 26 01/11/01 Per Plan 1.0 BPG 12.6 109.6 92 119.0 27 01/11/01 Per Plan 1.0 BPG 13.4 108.5 91 119.0 28 01/11/01 Per Plan 1.0 BPG 12.7 110.9 93 119.0 0 February 20, 2001 1 EARTH SYSTEMS SOUTHWEST ' REPORT OF RELATIVE COMPACTIONS JOB NAME: Point Happy ' LOCATION: La Quinta, California FILE NO.: 07074-02 REPORT NO: 01-02-753 Pave 2 of 2 Test No Date Tested Description Elevation %MoistureDry Density Relative Maximum In Place In Place Compaction Density Grading 29 01/12/01 Per Plan FPG 11.2 107.3 90 119.0 30 01/12/01 Per Plan FPG 9.2 109.6 92 119.0 31 01/12/01 Per Plan FPG 12.0 108.7 91 119.0 32 01/12/01 Per Plan FPG 10.1 111.9 94 119.0 33 01/12/01 Per Plan FPG 10.6 109.7 92 119.0 34 01/12/01 Per Plan FPG 12.9 109.5 92 119.0 35 01/12/01 Per Plan FPG 11.3 113.6 95 119.0 36 01/12/01 Per Plan FPG 11.0 112.3 94 119.0 37 01/12/01 Per Plan 3.0 BPG 10.2 107.5 90 119.0 38 01/12/01 Per Plan 2.0 BPG 9.4 108.0 90 119.0 39 02/16/01 Per Plan 1.0 BPG 9.6 111.9 94 119.0 40 02/16/01 Per Plan FPG 8.7 110.6 93 119.0 41 02/16/01 Per Plan 1.0 BPG 7.6 109.7 92 119.0 42 02/16/01 Per Plan FPG 8.5 111.4 94 119.0 BPG = Below Pad Grade FPG = Finish Pad Grade 0 February 20, 2001 EARTH SYSTEMS SOUTHWEST i Lm� ID w Mw t COMPACTION' • .HAPPY DESERT CITIES DEVELOPMENT 78-600 HIGHWAY 11 1 LA QUINTA, CALIFORNIA 92253 GEOTECHNICAL ENGINEERING AND LIMITED GEOLOGIC REPORT PROPOSED COMMERCIAL DEVELOPMENT NW CORNER OF HWY 111 & WASHINGTON STREET LA QUINTA, CALIFORNIA File No. 07074-01 99-03-759 Revised 3-24-99 Earth System rl%ZZF Southwest March 8, 1999 Revised 3-24-99 Desert Cities Development 78-600 Highway 111 La Quinta, California 92253 Consultants Attention: Mr. Dave Smoley Subject: Geotechnical Engineering Report Project: Proposed Commercial Development Northwest Corner of Washington Street and Highway 111 La Quinta, California 79-811B Country Club Drive Bermuda Dunes, CA 92201 (760)345-1588 (800)924-7015 FAX (760) 345-7315 File No. 07074-01 99-03-759 It is our pleasure to present this Geotechnical Engineering Report prepared for the proposed commercial development to be located at the northwest corner of Highway 111 and Washington Street in the City La Quinta California. This report. presents our findings and recommendations for general site development and foundation design, incorporating the tentative information supplied to our office. This report should stand as a whole, and no part of the report should be excerpted or used to exclusion of any other part. This report completes our scope of services in accordance with our agreement dated December 16, 1998. Other services that may be required, such as plan review and grading observation are additional services and will be billed according to the Fee Schedule in effect at the time services are provided. This report was revised to include slope stability discussions and conclusions inadvertently omitted from the original report dated March 8, 1999. 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 CONSULTANTS Southwest JnoQ�pEESS/ , V-' Z �� 0� L Shelton L. Stringer �,�„` m m David Goodrich GE 2266 Na2268 X '° CEG 1932 6-3 SER/pc r sT cttN��P��a ' Distribution: 6/Desert Cities Deve �rFOF CAQF�� 1/VTA File IBD File GOODRICH No. EG1932 CERTIFIED ENGINEERING , GEOLOGIST . TABLE - OF CONTENTS Page Section 1 INTRODUCTION................................................................ 1 1.1 Project Description........................................................... ..... 1 1.2 Site Description...................................................................... 1 1.3 Purpose and Scope of Work ...................................................... 1 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 .............................. 4 J 34.1 Seismic Hazards ....................................... 4 3.4.2 Secondary Hazards......................................................... 6 3.4.3. Site Acceleration and UBC Seismic Coefficients ...............:....... 7 --, Section 4 CONCLUSIONS................................................................. 9 ' Section 5, RECOMMENDATIONS. 10 SITE DEVELOPMENT AND GRADING 5.1 - Site Development-Grading.......................................................... 10 5.2 Slope Stability of Graded Slopes .................................................. 11 5.3 Excavations and Utility Trenches . 11 5.4 Foundations 12 ....................................................................... 5.5 Slabs-on-Grade ' ...................................................................... STRUCTURES 13 5.6 Retaining Walls...................................................................... 14 5.7 Mitigation of Soil Corrosivity on Concrete ....................................... 14 5.8 Seismic Design Criteria............................................................. 16 5.9 Pavements ............................................................................ 17 Section 6 LIMITATIONS AND ADDITIONAL SERVICES 18 ..................... 6.1 Uniformity of Conditions and Limitations ........................................ 18 6.2 Additional Services.................................................................. 19 REFERENCES............................................................................. 20 APPENDIX A Figure Vicinity Map and Boring Location Map ........................................... 1-2 SiteGeologic Map................................................................... 3 Log Borings of Table 1 - Fault Parameters APPENDIX B �{ Laboratory Test Results March 8, 1999 -1- File No. 0707-01 ' Revised 3-24-99 99-03-759 ' Section 1 INTRODUCTION 1.1 Project Description This Geotechnical Engineering Report has been prepared for the proposed commercial development to be located at the northwest corner of Highway 111 and Washington Street in the City of La Quinta, California. Five restaurant buildings, one bank building, one office building and two gas stations are proposed. We anticipate that the proposed structures will be of wood -frame and stucco construction and will be supported by conventional shallow continuous or pad footings. Site development will include site grading, building pad preparation, underground utility installation, street and parking lot construction, and concrete driveway and sidewalk placement. The proposed access drivewayfrom Highway 111 will receive excavation into the existing g Y n� rock slope. Design of this proposed cutslope has not been completed at this time. ' We used structural building column loads of up to 50 kips and a maximum wall loading of 3 kips per linear foot as a basis for the foundation recommendations. All loading is assumed to be dead plus actual live load. If actual loading is to exceed these assumed values, it may be necessary to ,1 reevaluate the given recommendations. JJ 1.2 Site Description ' The proposed commercial development is to be constructed on a vacant parcel at the northwest corner of Highway 111 and Washington Street. The lot is currently vacant of structures and is fairly level with some recent improvements having recently been completed along the Whitewater Channel. These improvements include concrete armament and an access area along the top of the embankment. Some grading was performed in the past as a result of the construction of Highway 111 and Washington Street and the along the drainage channel located at the rear of the lot. As part of the site improvements, a proposed ingress/egress driveway is to be constructed at the southwest corner of the site. In order to make room for the proposed driveway, the existing rock outcrop, located along the west side of the site will require partial excavation and removal. This will result in a cut slope in the bedrock. The development of the proposed office building may also include the partial removal of bedrock and/or surface rocks and boulders that may be unstable. NJ 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: • Geological site reconnaissance. • Geologic mapping of the site. • Shallow subsurface exploration by drilling seven exploratory borings to depths ranging from 6 to 31 feet. • Laboratory testing of selected soil samples obtained from the exploratory borings. • Review of selected published technical literature pertaining to the site. Evaluation of field and laboratory data. �j 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. EARTH SYSTEMS CONSULTANTS SOUTHWEST '0 March 8, 1999 -2- File No. 07074-01 Revised 3-24-99 99-03-759 This report contains the following: • Discussions on subsurface soil and groundwater conditions. •. Discussions on regional and local geologic conditions. Discussions on the stabilityof adjacent rock slopes. � • Discussions on geologic and seismic hazards. • Graphic and tabulated results of laboratory tests and field studies. • _ Recommendations regarding: b • site development and grading criteria. • excavation conditions and buried utility installations. • . structure -foundation type and design. yp s bn. • 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. • pavement structural sections. ' Not Contained In This Report: Although available through Earth Systems Consultants 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. • Investi ation for the presence or absence of wetlands, g p ds, hazardous or toxic materials m the soil, surface water, groundwater, or air on, below, or adjacent to the subject property. EARTH SYSTEMS CONSULTANTS SOUTHWEST 11 March 8, 1999 -3- File No. 0707.1-01 Revised 3-24-99 99-03-759 Section 2 11 METHODS OF INVESTIGATION 2.1 Field Exploration Seven borings were drilled to maximum depths ranging from 6 to 31 feet below the existing ground surface to observe the soil profile and to obtain samples for laboratory testing. The borings ,1 were drilled on January 21, 1999, using 6 -inch outside diameter hollow -stem augers, and powered �JJ by a CME 45 truck -mounted drilling rig. The approximate locations of the test borings were established by pacing and sighting from existing topographic features. The approximate boring ' locations are shown on Figure 2. Samples were obtained within the test borings with a Modified California (M.C.) ring sampler (ASTM D 3550 with shoe similar to ASTM D 1586). The M.C. 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 downhole hammer dropping 30 inches in accordance with ASTM D 1586. Bulk samples of the soils encountered were also gathered from the auger cuttings. The final log of the boring represent our interpretation of the contents of the field loo, and the results of laboratory testing performed on the samples obtained during the subsurface investigation. 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 were considered representative of 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 laboratory testing program consisted of the following tests: ' In-situ Moisture Content and Unit Dry Weight for the ring samples s (ASTM D 2937). Direct Shear (ASTM D 3080) to evaluate the relative frictional strength of the soils. Remolded specimens were placed in contact with water at least 24 hours before testing and were.then sheared under normal loads ranging from 0.5 to 2.0 kips per square foot. Maximum density tests were performed to evaluate the moisture -density relationship of typical soil encountered (ASTM D 1557-91). 11 • Particle Size Analysis (ASTM D422) to classify and evaluate soil composition. The gradation characteristics of selected samples were made by hydrometer and sieve analysis procedures. Chemical Analyses (Soluble Sulfates & Chlorides, pH, and Electrical Resistivity) to evaluate the corrosivity of the soil on concrete and steel. EARTH SYSTEMS CONSULTANTS SOUTHWEST ' March 8, 1999 -4- File No. 07074-01 Revised 3-24-99 99-03-759 Section 3 DISCUSSION 3.1 Soil Conditions The field exploration indicates that site soils consist primarily of medium dense to dense, silty sand (SM) with gravel. Some sandy silty (ML) was encountered at depths greater than 7 feet. ' Weathered granite was encountered at 28 foot depth in Boring 5. The boring logs provided in Appendix A include detailed descriptions of the soils encountered. ,1 Soils should be readily cut by normal grading equipment. ff 3.2 Groundwater Free groundwater was not encountered in the borings during exploration. The depth to groundwater in the area is believed to be in excess of 100 feet. Groundwater levels may fluctuate with precipitation, flow within the Whitewater Stormwater Channel, precipitation, drainage, and site grading. Groundwater should not be a factor in design or construction. 3.3 Geologic Setting . Regional Geology: The site lies within in 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 portion 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, 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 Geolgg., The project site is located on the south bank of the Whitewater River channel in the ' middle portion of the Coachella Valley. The upper sediments observed onsite consist of fine to coarse-grained sands with interbedded clays, silts, gravels, `and cobbles of aeolian and alluvial origin. The depth to crystalline basement rock beneath the site is estimated to be in excess of 2000 feet (Envicom, 1976). 3.4 Geologic Hazards Geologic hazards that may affect the region include seismic hazards (surface fault rupture, ground shaking, 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: Our research of regional faulting indicates that 23 known active faults or seismic zones lie within 47 miles of the project site as shown on Table 1 in Appendix A. The Maximum 1Magnitude Earthquake (M,,,,x) listed was taken from published geologic information available for 'J EARTH SYSTEMS CONSULTANTS SOUTHWEST 1 ] March 8, 1999 -5- File No. 07071-01 Revised 3-24-99 99-03-759 11 each fault (CDMG, 1996). The Mm,r corresponds to the maximum earthquake believed to be tectonically possible. t]The primary seismic hazard to the project site is strong groundshaking from earthquakes along the San Andreas and San Jacinto Faults. A further discussion of site acceleration from groundshaking follows in Section 3.4.3. ,J Surface Fault Rupture: The project site does not lie within a currently delineated State of California, Alquist- Priolo Earthquake Fault Zone. (Hart, 1994). Well -delineated fault lines cross through this region as shown on California Division of Mines and Geology (CDMG) 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., NJ Historic Seismicity: Five historic seismic events (5.9 M or greater) have significantly affected the Coachella Valley this century. They are as follows: Desert Hot Springs Earthquake - On December 4, 1948, a magnitude 6.5 M, (6 -OM,) earthquake occurred east of Desert Hot Springs (Proctor 1968). 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 (USGS 1987). This event was strongly felt to the Palm Springs area and caused structural damage, as well as injuries ' Desert Hot Springs Earthquake - On April 22, 1992, a magnitude 6.1 M, (6.1MW) earthquake occurred in the mountains 9 miles east of Desert Hot Springs (OSMS 1992). 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 (7.3MH,) 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 (6.4MH,) earthquake occurred near Big Bear Lake. No significant structural damage from these earthquakes was reported in the Palm Springs area. Seismic Risk: While accurate earthquake predictions are not possible, various agencies have JJ published extensive statistical risk analyses. In 1996, the California Division of Mines and Geology (CDMG) and the United States Geological Survey (USGS) completed the latest generation of probabilistic seismic hazard maps for use in the 1997 UBC. 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 significant earthquake would occur between 1994 to 2024 along the Coachella segment of the San Andreas Fault. The primary seismic risk to the project site is the San Andreas Fault. Geologists believe that the San Andreas Fault has characteristic earthquakes that rupture each fault segment. The estimated characteristic earthquake is magnitude 7.4 for the Southern (Coachella) Segment of the fault. This segment has the longest elapsed time since rupture than any other portion of the San Andreas Fault. The last rupture occurred about 1690 AD, based on dating of trench surveys 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 along the San Bernardino Mountain Segment to the north indicates that both it and the Southern (Coachella) _ Segment may have both ruptured together in 1450 and 1690 AD (WGCEP, 1995). EARTH SYSTEMS CONSULTANTS SOUTHWEST March 8, 1999 -6- File No. 07074-01 Revised 3-24-99 99-03-759 il . 1 3.4.2 Secondary Hazards m. Secondary seismic hazards related to deformation, areal subsidence, tsunamis, _ tsunamis is non-existent. At the present immediate vicinity of the site. Therefore, �-, time. ground shaking include soil liquefaction, ground and seiches. The site is far inland so the hazard from time, no water storage reservoirs are located in the hazards from seiches are considered negligible at this 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 in the Riverside County liquefaction study zone. Ground Deformation and Subsidence: Non -tectonic ground deformation consists of cracking of the ground with little to no displacement. This type of deformation is not caused by fault rupture. Rather it is generally associated with differential shaking of two or more geologic units with differing engineering characteristics. Liquefaction may also cause ground deformation. As the site is flat with consistent geologic material, and has a low potential for liquefaction, the potential for ground deformation is also considered to be low. The potential for seismically induced ground subsidence is considered to be relatively low at the ' site. Dry sands tend to settle and densify when subjected to earthquake shaking. The amount of settlement is. a function of relative density, groundshaking (cyclic shear strain), and earthquake duration (number of strain cycles). Slope Instability: The majority of the site is relatively flat. Therefore, potential hazards from slope instability, landslides, or debris flows are considered negligible in the eastern flat -lying portion of E71 instability, site. Because of the anticipated high strength of the bedrock materials in the slope at the western end of the site, this slope is considered grossly stable in its existing condition. However, because of the potential for high ground accelerations at the site (see the following section), surficial failures such as rockfall and debris flows cannot be precluded in the event of a nearby large earthquake. No grading plans are currently available showing the configuration of the proposed cut slope in the southwest corner of the site. As a result, the potential height of this slope is unknown at this time. However, Figure 2 shows the relationship of the currently proposed entrance roadway to the existing slope. Based on this relationship, we assume that an east and southeast facing cut slope will be required along the northwest side of the entrance roadway. Our geologic mapping shows that the predominant orientation of significant fractures in this area is dipping steeply to the west. This orientation is generally favorable for an east to southeast facing cut slope since fracture planes dipping out -of -slope would not daylight within the cut slope face. Therefore, based on this preliminary mapping, we expect that a fairly steep cut slope, on the order of 3/4:1 (horizontal: vertical) would be grossly stable and would have a relatively low probability of exposing large unstable blocks or wedges. We estimate that such a 3/4:1 slope would be on the order of 40 feet high. Smaller loose and unstable blocks may be exposed during grading and could require removal or stabilization on an individual basis. These conclusions will require verification by geologic inspection during excavation of the cut slope. If unstable blocks or wedges are identified during slope construction, additional . stabilization mitigation techniques such as scaling, rock bolting, or a rockfall mesh system could be required. EARTH SYSTEMS CONSULTANTS SOUTHWEST ' March 3, 1999 -7- File No. 07074-01 Revised 3-24-99 99-03-759 The area of the proposed office building, at the northwest corner of the site is potentially P P b p sally vulnerable to falling rocks in the event of a large earthquake. Therefore, we do not recommend that spaces where people spend significant amounts of time (patios, etc.) be planned at ground level at the rear (west side) of this structure. This existing slope is inclined at approximately 1:1. At this inclination, any dislodged rocks would be expected to roll, rather than bounce down the slope. However, some bouncing away from the slope face could occur as a result of impacts with large rocks on the slope face. Therefore, second story balconies or similar spaces should be kept a minimum of 10 feet from the slope face. The stability of individual boulders or rock outcroppings 1 should be evaluated in more detail when building plans are available. J Flooding: The prokct site does not lie within a designated FEMA 100 -year flood lain. The b Y P 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 UBC Seismic Coefficients Site Acceleration: To assess the potential intensity of ground motion, we have estimated the horizontal peak ground acceleration (PGA). 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 is an inconsistent scaling factor to compare to the UBC 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 r peak acceleration (EPA) is used in structural design. EARTH SYSTEMS CONSULTANTS SOUTHWEST I]. March 8, 1999 -8- File No. 07074-01 Revised 3-24-99 99-03-759 The following table provides the probabilistic estimate of the PGA and EPA taken from the 1996 CDMG/USGS seismic hazard maps. Estimate of PGA and . EPA from 1996 CDMG/USGS Probabilistic Seismic Hazard Maps Risk Equivalent Return Period (years) PGA (Q) (1) Approximate EPA (a) (2) 10% exceedance in 50 years 475 0.51 0.46 Notes: 1. Based on soft rock site, Site Class SB 2. Spectral acceleration (SA) at period of 0.3 seconds divided by 2.5 factor for 5% damping as defined by the Structural Engineers Association of California (SEAOC, 1996). UBC Seismic Coefficients: The Uniform Building Code (UBC) seismic coefficients are based on ' an Design Basis Earthquake (DBE) that has an earthquake ground motion with a 10% probability of occurrence in 50 years. The UBC seismic force provisions should be regarded as a minimum design in that it allows for inelastic yielding of structures. The UBC design criteria permit Jstructural damage and possible loss of use after an earthquake. The PGA and EPA estimates given above are provided for information on the seismic risk inherent in the UBC design. The following table lists the relevant seismic and site coefficients given in Chapter 16 of the 1994 ' and 1997 Uniform Building Code (UBC). The 1997 UBC seismic provisions are more stringent for areas less than 10 km (6.2 miles) from major seismic sources. I]. 1] n UBC Seismic Cnefficientc for ChnntPr 16 Prnvic;^— UBC Soil Seismic Distance Near Source Seismic Coefficients Code - Profile Source to Critical Factors Edition Type Type Source Na Nv Ca Cv 1994 S3 --- --- --- --- Z = 0.4 Z =0.4 S factor =1.5 Ref. Table 16-J --- --- --- --- 16-I 16-I 1997 Sp A 8.9 km 1.04 1.29 0.44Na 0.64Nv (stiff soil) = 0.46 = 0.82 Ref. Table 16-J 16-U --- 16-9 16-T 1642 16-R Seismic Zoning: The Seismic Safety Element of the 1984 Riverside County General Plan establishes groundshaking hazard zones. The project area is mapped in Ground Shaking Zone. Ground Shaking Zones are based on distance from causative faults and underlying soil types. These groundshaking hazard zones are used in deciding suitability of land use. EARTH SYSTEMS CONSULTANTS SOUTHWEST March 8, 1999 -9- File No. 07074-01 Revised 3-24-99 99-03-759 ,1 Section 4 JJ _ 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. • The primary geologic hazard relative to site development is severe ground shaking from ' earthquakes originating on nearby faults. In our opinion, a major seismic event originating on the local segment of the San Andreas fault zone would be the most likely cause of significant earthquake activity at the site within the estimated design life of the proposed development. Thero'ect site Ys in seismic Zone 4 a e p � s defined in the Uniform Buildingd Code. A qualified professional who is aware of the site seismic setting should design any permanent structure constructed on the site. • Ground subsidence from seismic events or hydroconsolidation is a potential hazard in the Coachella Valley area. Adherence to the following grading and structural recommendations should limit 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 minimize seasonal flooding and erosion should be incorporated into site grading plans. Dust control should also be implemented during construction. • For planning purposes, the anticipated cut slope along the northwest side of the entrance roadway are expected to be grossly stable at an inclination of 3/4:1 (horizontal: vertical). This 1� conclusion is tentative pending review of final grading plans showing the orientation and height of the proposed slope. Further confirmation will be required using geologic mapping during slope construction. Additional stabilization could be required based on the findings during slope construction. • The proposed office building at the northwest corner of the site is potentially vulnerable to falling rocks during a large earthquake. • Other geologic hazards including ground rupture, liquefaction, seismically induced flooding, and landslides are considered low or negligible on this site. • The upper soils were found to be relatively dense. In our opinion, the soils within the building area will require minimal compaction to improve bearing capacity and limit settlement from static loading. • We recommend that Earth Systems Consultants Southwest (ESCSW) be retained to 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 ESCSW prior to grading. Plans should include the grading plans, foundation plans, and foundation details. Preferably, structural loads ' should be shown on the foundation plans. il EARTH SYSTEMS CONSULTANTS SOUTHWEST March 8, 1999 -10- File No. 07074-01 Revised 3-24-99 99-03-759 Section 5 RECOMMENDATIONS SITE DEVELOPMENT AND GRADING 5.1 Site Development - Grading '1 A representative of ESCSW prior to placing fill should observe site grading and the bottom of all excavations. Local variations in soil conditions may warrant increasing the depth of recompaction �■� and/or over -excavation. Clearing and Grubbing: Prior to site grading any existing vegetation, trees, large roots, pavements, foundations, uncompacted fill, construction debris, trash, and any abandoned underground utilities should be removed from the proposed building and pavement areas. The surface should be stripped of organic growth along with other debris and removed from the construction area. Any areas disturbed during demolition and clearing should be properly backfilled and compacted as described below. Building Pad Preparation: Because of the relatively dense nature of the majority of the site soils, we recommend minor regrading the upper soils in the building area. The existing surface soils within the building pad areas should be over -excavated to 12 inches below existing grade or to the footing level (whichever is lower). The over -excavation should extend for 5 feet beyond the outer edge of exterior footings. The bottom of the sub -excavation should be scarified, moisture conditioned, and recompacted to at least 90% relative compaction (ASTM D1557) for a depth of 12 inches. Subarade Preparation: In areas to receive pavements or hardscape, the ground surface should be i� scarified, moisture conditioned, and compacted to at least 90% relative compaction (ASTM D1557) for a depth of 12 inches below finished subgrades. Compaction should be verified by testing. 1 Engineered Fill Soils: The native granular soil is suitable for use as engineered fill and utility trench backfill. The native soil should be placed in maximum 8 -inch lifts (loose) and compacted at least 90% relative compaction (ASTM D1557) near optimum moisture. Compaction should be verified by testing. All rocks larger than 6 inches in greatest dimension should be removed from fill or backfill material. All imported fill soils (if required) 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 20% passing the No. 200 sieve. The geotechnical engineer should evaluate the import fill soils before hauling to the site. However, import soil will not be prequalified by ESCSW. 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 D1557) at optimum moisture ± 2 percent. Shrinkage: The shrinkage factor for earthwork is expected to range from 5 to 15% for the upper J 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 about less than 0.1 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 EARTH SYSTEMS CONSULTANTS SOUTHWEST I] Il n 17 March 8, 1999 - l l - File No. 07074-01 Revised 3-24-99 99-03-759 drainage is not provided. Drainage should be maintained for paved areas. Water should not pond on or near paved areas 5.2 Slope Stability of Graded Slopes All unprotected permanent graded soil slopes should not be steeper than 3:1 to reduce wind and rain erosion. Soil slopes protected with ground cover may be as steep as 2:1. However, maintenance with motorized equipment may not be possible at this inclination. Slope stability calculations were not performed for soil slopes because of the expected minimal slope height (less than 5 feet). If soil slope heights exceed 5 feet, engineering calculations should be performed to evaluate the stability of 2 to 1, horizontal to vertical, slopes. Fill slopes should be overfilled and trimmed back to competent material. Cut slopes in bedrock materials can be tentatively planned at an inclination of 3/4:1. The stability of these slopes should be further evaluated after completion of grading plans showing slope heights and orientations. 5.3 Excavations and Utility Trenches All excavations should be made in strict accordance with CalOSHA requirements. From our site exploration and knowledge of the general area, we believe 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 deep 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, road department, etc.) Utility trench backfill within private property should be placed in conformance with the provisions of this report relating to minimum compaction standards. 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 by ESCSW to monitor compliance with these recommendations. EARTH SYSTEMS CONSULTANTS SOUTHWEST ' March 8, 1999 -12- File No. 07074-01 Revised 3-24-99 99-03-759 ' STRUCTURES In our professional opinion, the structure foundation can be supported on shallow foundations bearing on a zone of properly prepared and compacted soils placed asrecommended in Section 5.1. The recommendations that follow are based on "very low" expansion category soils. 5.4 Foundations Footing design widths, depths, and reinforcing are the responsibility of the Structural Engineer. Footings should be design for structural considerations and the geotechnical conditions described ' in this report. A minimum footing depth of 12 inches below lowest adjacent grade should be maintained. 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: 1800 psf for dead plus reasonable live loads. 2400 psf for wind and seismic considerations. ' Wall foundations should be 15 -inches wide and embedded 18 inches belowrade for two-story ry structures. NJ Isolated pad foundations, 2 x 2 foot minimum in plan and 18 inches below grade: 2000 psf for dead plus reasonable live loads. ,-, 2650 psf for wind and seismic considerations. Allowable increases of 200 psf per each foot of additional footing width and 300 psf for each additional foot of footing depth may be used. The maximum allowable bearing pressure should ' limited to 3000 psf. The allowable bearing values indicated have been determined based upon the anticipated maximum loads indicated in Section 1.1 of this report. If the indicated loading is exceeded then 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, split between the top and the bottom of the footing. This reinforcing is not intended to supersede ' any structural requirements provided by the structural engineer. Foundation excavations should be observed by the geotechnical engineer during excavation and prior to placement of reinforcing steel or concrete. Local variations in conditions may require deepening of footings Expected Settlement: Estimated total static settlement, based on footings founded on firm soils as ' recommended, should be less than 1 inch. Differential settlement between exterior and interior bearing members should be less than 1/2 -inch. 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 stem walls. Lateral capacity is based partially on the assumption that any required backfill adjacent to foundations and grade beams is properly compacted. An allowable coefficient of friction of. 0.40 may be used for dead load forces. An allowable equivalent fluid pressure of 300 pcf may be included for resistance to lateral loading. These values EARTH SYSTEMS CONSULTANTS SOUTHWEST March 8, 1999 -13- File No. 07074-01 ' Revised 3-24-99 99-03-759 ' include a factor of safety of 1.5. Passive resistance and frictional resistance may be combined in determining the total lateral resistance. However, the friction factor should be reduced to 0.28 of dead load forces. A one-third (1/3) increase in the passive pressure may be used when calculating resistance to wind or seismic loads. r 5.5 Slabs -on -Grade Subgrade: Concrete slabs -on -grade and flatwork should be supported by compacted soil placed in accordance with Section 5.1 of this report. Vapor Barrier: In areas of moisture sensitive floor coverings, an appropriate vapor barrier should be installed in order to minimize moisture transmission from the subgrade soil to the slab. We recommend that ad impermeable membrane (6 -mil visqueen) underlie the floor slabs. The membrane should be covered with 2 inches of sand to help protect it during construction and to r aide in concrete curing. The sand should be lightly moistened just prior to placing the concrete. Low -slump concrete should be used to help minimize shrinkage. ' Slab thickness and reinforcement: Slab thickness and reinforcement of slab -on -grade are contingent upon the structural engineer's or architect's recommendations 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. Concrete slabs and flatwork should be -a minimum of 4 inches thick. We suggest that a minimum reinforcement for concrete slabs consist of a minimum of No. 3 rebars at 18 -inch centers, both horizontal directions, placed at slab mid -height to resist cracking. Concrete floor slabs may either be monolithically placed with the foundations or doweled after footing placement. The thickness and reinforcing given are not intended to supersede any structural requirements provided by the structural engineer. The project architect or geotechnical engineer should continually observe all reinforcing steel in slabs during placement of concrete to check for proper location within the slab. Control Joints: Control joints should be provided in all concrete slabs -on -grade at a maximum ' spacing of 36 x 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 randomly oriented contraction cracks. Contraction joints in the slabs should be tooled at the time of the pour or saw cut (1/4 of slab depth) within 8 hours of concrete placement. Construction (cold) joints should either be thickened buttjoints with one-half inch dowels at 24 - 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 prevent moisture or foreign material intrusion. Precautions should be taken to prevent curling of slabs in this and desert region. 1] EARTH SYSTEMS CONSULTANTS SOUTHWEST 11 March 8, 1999 Revised 3-24-99 5.6 Retaining Walls -14- File No. 07074-01 99-0;-759 The table below presenis lateral earth pressures for use in retaining wall design. The values are given as equivalent fluid pressures without surcharge loads or hydrostatic pressure. Notes: Lateral Pressures and Sliding Resistance (1) Granular Backfill Passive Pressure 450 pcf Active Pressure (cantilever walls) 33 pcf able to rotate 0.1 % of structure height At -Rest Pressure (restrained walls) 55 pcf Dynamic Lateral Earth Pressure (2) acting at mid height of structure, 20H psf where H is height of backfill in feet Base Lateral Sliding Resistance Dead load X Coefficient of Friction: 0.55 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 need not consider this increased pressure. 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 loads are applied within a zone from 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 2 feet of native soil. 1] Drainage: A backdrain or an equivalent system of backfill drainage should be incorporated into the retaining wall design. Our firm can provide construction details when the specific application is determined. Backfill immediately behind the retaining structure should be a free -draining granular material. In this case the native soils are considered free draining. Waterproofing should be per the Architect's specifications. Water should not be allowed to pond near the top of the wall. To accomplish this, the final backfill grade should be such that all water is diverted away from the retaining wall. Backfill 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. 5.7 Mitigation of Soil Corrosivity on Concrete Selected chemical analyses for corrosivity were conducted on samples at the project site The native soils were found to have low sulfate ion concentration (0.001%) and low chloride ion concentrations (0.003%). 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 Uniform Building Code requires that increased quantities of Type II Portland Cement be used at a low water/cement ratio when concrete is subjected to moderate sulfate concentration. EARTH SYSTEMS CONSULTANTS SOUTHWEST J March 8, 1999 Revised 3-24-99 -15- File No. 07074-01 99-03-759 A minimum concrete cover of 3 inches should be provided around steel reinforcing or embedded components exposed to native soil or landscape water (to 18 inches above grade).- Additionally, the concrete should be thoroughly vibrated during placement. Laboratory 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 pipes can be achieved by using epoxy corrosion inhibitors, asphalt coatings, cathodic protection, or encapsulating with densely consolidated concrete. A qualified corrosion engineer should be consulted regarding mitigation of the corrosive effects of site soils on metals. EARTH SYSTEMS CONSULTANTS SOUTHWEST March 8, 1999 -16- File No. 07074-01 Revised 3-24-99 99-03-759 5.8 Seismic Design Criteria This site is subject to strong ground shaking due to potential fault movements along the San ,J Andreas and San Jacinto Faults. Engineered design and earthquake -resistant construction are the J common solutions to increase safety and development of seismic areas. The minimum seismic design should comply with the latest edition of the Uniform Building Code for Seismic Zone 4 using the seismic coefficients given in Section 3.4.3 of this report. the table below. The 1997 ' UBC seismic provisions are more stringent for sites lying close to major faults. The UBC seismic coefficients are based on scientific knowledge, engineering judgment, and ' compromise. Factors that play an important role in dynamic structural performance are: (1) effective peak acceleration (EPA), (2) duration and predominant frequency of strong ground motion, (3) the period of the structure, (4) soil -structure interaction, (5) total resistance capacity of the system, (6) redundancies, (7) inelastic load -deformation behavior, and (8) the modification of damping and effective period as structures behave inelastically. Factors 5 to 8 are accounted by the structural ductility factor (R) used in deriving a reduced value for design base shear. If further information on seismic design is needed, a site-specific probabilistic seismic analysis should be ' conducted. The intent of the UBC 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 UBC lateral force requirements should be considered as a minimum design criteria. The owner and the designer should evaluate the level of risk and performance that is acceptable. Performance. based criteria could be set in the design. The design engineer has the responsibility to interpret and adapt the principles of seismic behavior and design to each structure using experience ' and sound judgment. The design engineer should exercise special care so that all components of the design are all fully met with attention to providing a continuous load path. An adequate quality assurance and control program is urged during project construction to verify that the design plans and good construction practices are followed. This is especially important for sites lying close to the major seismic sources. F. 1] EARTH SYSTEMS CONSULTANTS SOUTHWEST 01. 1_ __ - March 8, 1999 ' Reviscd 3-24-99 ' 5.9 Pavements F: 17 1] -17- File No. 07074-01 99-03-759 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 is necessary to prolong the service life of the pavements. The following table provides our recommendations for pavement sections. RECOMMENDED PAVEMENTS SECTIONS R -Value Suberade Soils - 50 (assumed) T)Pcian MPthnrl - (,AT 7P ANC 1000 Notes: 1. Asphaltic concrete should be Caltrans, Type B, 1/2 in. maximum -medium grading, compacted to a minimum of 95% of the 75 -blow Marshall density (ASTM D1559). 2. Aggregate base should be Caltrans Class 2 (3/4 in. maximum), compacted to a minimum of 95% of ASTM D1557 maximum dry density. 3. All pavements should be placed on 12 inches of moisture conditioned subgrade, compacted to a minimum of 90% of ASTM D1557 maximum dry density. 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. I EARTH SYSTEMS CONSULTANTS SOUTHWEST - Flexible Pavements Rigid Pavements V Traffic Index Pavement Use Asphaltic Concrete Thickness Aggregate 'Base Thickness Portland Cement Concrete Aggregate Base Thickness (assumed) (in.) (in.) (in.) (in.) 4.0 Auto Parking Areas 2.5 4.0 4.0 4.0 5.0 Driveways 3.0 4.0 5.0 4.0 10.0 Hwy 111 or 6 8 Washington St Notes: 1. Asphaltic concrete should be Caltrans, Type B, 1/2 in. maximum -medium grading, compacted to a minimum of 95% of the 75 -blow Marshall density (ASTM D1559). 2. Aggregate base should be Caltrans Class 2 (3/4 in. maximum), compacted to a minimum of 95% of ASTM D1557 maximum dry density. 3. All pavements should be placed on 12 inches of moisture conditioned subgrade, compacted to a minimum of 90% of ASTM D1557 maximum dry density. 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. I EARTH SYSTEMS CONSULTANTS SOUTHWEST March 8, 1999 -18- File No. 07074-01 Revised 3-24-99 99-03-759 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. ,J 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 or appropriate 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. NJ In the event that any changes in the nature, design, or location of the building 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 his representative, has the responsibility that the information and recommendations contained herein are brought to the attention of the architect and engineers for the project and are incorporated into the plans and specifications for the project. The owner, or his representative, also has the responsibility to take the necessary steps to see that the general contractor and all subcontractors carry out such recommendations in the field. It is further understood that the owner or his representative is responsible for submittal of this report to the appropriate governing agencies. As the Geotechnical Engineer of Record for this project, ESCSW 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 their authorized agents ' ESCSW 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 ESCSW is not accorded the privilege of making this recommended review, we can assume no responsibility for misinterpretation of our recommendations. 11 EARTH SYSTEMS CONSULTANTS SOUTHWEST 11 1 March 8, 1999 -19- File No. 0707.1-01 Revised 3-24-99 99-03-759 ' Although available through Earth Systems Consultants Southwest, the current scope of our services does not include an environmental assessment; or 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. Prior to purchase or development of this site, we suggest that an environmental assessment be conducted which addresses environmental concerns. 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 ESCSW 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 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 UBC Sections 1701 and 3317 or local grading ordinances. • Consultation as required during construction WINE Appendices as cited are attached and complete this report EARTH SYSTEMS CONSULTANTS SOUTHWEST ' March 8, 1999 -20- File No. 07074-01 Revised 3-24-99 99-03-759 REFERENCES Blake, B.F., 1989-1998, EQSEARCH, v.2, A Computer Program for the Estimation of Peak ' Horizontal Acceleration from California Historical Earthquake Catalogs, Users Manual, 104 p. ' Blake, B.F., 1998a, FRISKSP v. 3.01b, A Computer Program for the Probabilistic Estimation of Peak Acceleration and Uniform Hazard Spectra Using 3-D Faults as Earthquake Sources, User's Manual, 191 p. Blake, B.F., 1998b, Preliminary Fault -Data for EQFAULT and FRISKSP, 71 p. Boore, D.M., Joyner, W.B., and Fumal, T.E., 1993, Estimation of Response Spectra and Peak ' Accelerations from Western North American Earthquakes: An Interim Report; U.S. Geological Survey Open -File Report 93-509, 15 p. Poore, D.M., Joyner, W.B., and Fumal, T.E., 1994, Estimation of Response Spectra and Peak Acceleration from Western North American Earthquakes: An Interim Report, Part 2,; U.S. Geological Survey Open -File Report 94-127. California Department of Conservation, Division of Mines and Geology: Guidelines - for Evaluating and Mitigating Seismic Hazards in California, Special Publication 117, WWW Version. Campbell, K.W., 1990, Empirical Prediction of Near -Source Soil and Soft -Rock Ground Motion for the Diablo Canyon Power Plant Site, San Luis Obispo County, California; Consultant Report Prepared by Dames & Moore for the Texas Low -Level Radioactive Waste Disposal Authority, Dated September 1990, 110 p. Envicom, Riverside County, 1976, Seismic Safety Element. Hart, E.W. 1994 rev., Fault -Rupture Hazard Zones in California: California Division of Mines and Geology Special Publication 42, 34 p. 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. Joyner, W.B., and Boore, D.M., 1994, Prediction of Ground Motion in North America, in Proceedings of ATC -35 Seminar on New Developments in Earthquake Ground Motion Estimation and Implications for Engineering Design Practice, Applied Technology Council, 1994. Kramer, S.L., 1996, Geotechnical Earthquake Engineering: Prentice Hall, 651 p. 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, 59 p. Pyke, R., Seed, H. B. And Chan, C. K. (1975). Settlement of Sands Under Multidirectional Shaking, ASCE, Journal of Geotechnical Engineering, Vol. 101, No. 4, April, 1975. 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 CONSULTANTS SOUTHWEST March 8, 1999 -21- File No. 07074-01 Revised 3-24-99 99-03-759 Seed, H. B. and Idriss, I. M., 1982, Ground Motions and Soil'Liquefaction During Earthquakes. Seed, H. B., and Silver, M. L. (1972). Settlement of Dry Sands During Earthquakes, ASCE. Journal of Geotechnical Engineering, Vol. 98, No. 4, April, 1972. Sieh, K., Stuiver, M., and Brillinger, D., 1989, A More Precise Chronology of Earthquakes Produced by the San Andreas Fault in Southern California: Journal of Geophysical Research, vol. 94, no. B 1, January 10, 1989, pp. 603-623. Seih, Kerry, 1985, "Earthquake Potentials Along The San Andreas Fault", Minutes of The National Earthquake Prediction Evaluation Council, March 29-30, 1985, USGS Open File Report 85-507. 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. Van de Kamp, P. C., "Holocene Continental Sedimentation in the Salton Basin, California: A Reconnaissance". Geological Society of America, Vol 84, March 1973. 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. Il EARTH SYSTEMS CONSULTANTS SOUTHWEST APPENDIX A Location Map Boring Location Map Regional Geologic Map Logs of Borings Table 1 - Fault Parameters Ll Nk,511115-�-NAXUI .......... ............ Reference: La Quinta 7.5 min. USGS Quadrangle (photorevised 1980) Figure 1 Vicinity Map Project Name: Hwy 111 and Washington Development Project No.:07074-01 Scale: 1 2,000' Earth Systems Consultants 0 2,000 4,000 1 WRI Southwest 11 I Il lu 1111111/�/1111111��e■..-__-- R I I I - /•.•Wcw. i I 74K. I r• 1 l �Bi 6�1 I � ctasawo � I «msa<,w I I . Base Maps: Preliminary Boundary Map, prepared by'Dudek and Associates, dated Nov. 1998 and untitled and undated preliminary site plan provided by client ' .-A N tk LEGEND Approximate Boring Location Approximate Scale: 1" = 100' 0 100 200 Figure 2 -Site Map Proposed Commercial Development ,NW Corner Highway 111 and Washington Street La Quinta, California Project No.: 07074-01 Earth Systems Consultants Southwest r---------- �`�_ _� i ti'' i abs... �'� v•,.. I �- � .,...67 • •\' `\ I �\ O.O. M4 \ I \ \y I I . Base Maps: Preliminary Boundary Map, prepared by'Dudek and Associates, dated Nov. 1998 and untitled and undated preliminary site plan provided by client ' .-A N tk LEGEND Approximate Boring Location Approximate Scale: 1" = 100' 0 100 200 Figure 2 -Site Map Proposed Commercial Development ,NW Corner Highway 111 and Washington Street La Quinta, California Project No.: 07074-01 Earth Systems Consultants Southwest Y, 1 K� 7 � ;9i _'Xj .d� Approximate Scale: 1" = 50' 0 50 100 LEGEND Approximate Boring Location bat Orientation of Joint in Bedrock al/ Orientation of Quartz Dike in Bedrock Surficial Units Qal Quaternary Alluvium Bedrock Units Granite Gabbro Monzonite QaI Base Map: Preliminary Boundary Map, prepared by Dudek and Associates, dated November 1998 Figure 3 - Site Geologic Map Proposed Commercial Development NW Corner Highway 111 and Washington Street La Quinta, California Project No.: 07074-01 Earth Systems Consultants Vis. Southwest r0 1 it Earth System s'Consuitants Southwest 79-811 B Country Club Drive, Bermuda Dunes. CA 92201 Ph— 17AM idc_i CR4 cA v iuni- v Boring No: B1 Drilling Date: January 21, 1999 Project Name: Desert Cities Development at Hwy 111 and Washington Street Drilling Method: 6 -in. Hollow Stem Auger Project Number: 07074-01 Drill Type: CME 45 Boring Location: See Boring Location Plan Logged By: Cliff Batten Sample Type Penetration o rn N e � Description of Units Page 1 of 1 U. � Resistance E U rn e � a� v .. N ° Note: The stratification lines shown re resent the P m o (Blows/6") rn _ between soil lnd/or rock types Trend GraphicDry mtransate btion A i A U and the may be gradanonaBlow Count Density 0 SM SILTY SAND: Tan, dense, fine to coarse grained I 21/41 0.5 with fine gravel, dry 5 16/34 86.2 1.9 IVI SANDY SILT: Tan, medium dense to dense, dry 10 ■ 12/22 89.8 3.4 I S ■ 30/42 90.8 2.8 Total Depth: 16 feet No groundwater or rock encountered 20 25 r 30 — 35 —40 —45 0 Earth Systems Consig1tants Southwest 79-811 B Country Club Drive, Bermuda Dunes. CA 92201 Dionne f7AA%]AC tC00 ce Boring No: -B2 Drilling Date: January 21, 1999 Project Name: Desert Cities Development at Hwy 111 and Washington Street Drilling Method: 6 -in. Hollow Stem Auger Project Number: 07074-01 Drill Type: CME 45 Boring Location: See Boring Location Plan Logged By: Cliff Batten Sample Type Penetration o y P s Description of Units Page 1 of 1 r u Resistance U E A 'o Note: The stratification lines shown represent the (Blows/6") rn A a - types approximate bound between soil and/or rock Trend cDry Am A U and the transition may be gradational. Blow Count Density —0 - _ I SILTY SAND: Tan, dense, fine to very fine grained, ■ 21/36 100.9 0.5 ( I dry _ 22137 105.2 2.6 —5 ■ 15/27 90.9 2.3 Total Depth: 6 feet No groundwater or rock encountered — 10 — 15 — 20 — 25 — 30 — 35 —40 — 45 0 Earth Systems Consodtants Southwest 79-811 B Country Club Drive. Bermuda Dunes. CA 92201 Phnne (76n) US -1 536 PA v rrFn% a.0 Borin>; No: B3 Drilling Date: January 21, 1999 Project Name: Desert Cities Development at Hwy 111 and Washington Street Drilling Method: 6 -in. Hollow Stem Auger Project Number: 07074-01 Drill Type: CME 45 Boring Location: See Boring Location Plan Logged By: Cliff Batten Sample Type Penetration o rn y s Description of Units Page 1 of 1 p s A Resistance U E rn a°i A n B " .14 c Note: The stratification lines shown represent the P v o (Blows/6") >1 A rn ., Z' o =� i o approximate boundary between soil and/or rock types Graphic Trend A m rn .� A U and the transition may be gradational. Blow Count Dry Density 0 sm SILTY SAND: Tan, very dense to medium dense, 50/2" 1.0 fine to very fine grained, dry 5 14/17 94.2 1.9 10 27/21 95.5 5.3 - with some clay layers 15 20 ■ 32/50 Ell 84.9 3.6 Total Depth: 21 feet No groundwater or rock encountered 25 30 35 — 40 = 45 Earth Systems Con-41tants O Southwest �i 79-811 B Country Club Drive, Bermuda Dunes, CA 92201 Ph—l7h01 idS-t iRR PAY (740%7.1c.11 - Boring No: B4 Drilling Date: January 21, 1999 Project Name: Desert Cities Development at Hwy 1 I 1 and Washington Street Drilling Method: 6 -in. Hollow Stem Auger Project Number: 07074-01 Drill Type: CME 45 Boring Location: See Boring Location Plan Logged By: Cliff Batten ^ Type Yp Penetration y b` Description of Units Page 1 of 1 �. Resistance U rn u Ca C H 'o Note: The stratification lines shown represent the a Y u o (Blows/6") >, a .. "3 approximate boundary between soil and/or rock types Graphic Trend A m' i A U and the transition may be gradational. Blow Count Dry Density 0 I S1v1 SILTY SAND: Tan, very dense, fine to very fine 37/50 for 2" 95.9 1.5 grained, dry 5 . 34/50 93.2 1.8 I l� SANDY SILT: Tan to gray, very dense, dry, with 10 ■ 24/50 88.8 2.9 silty clay layers 15 20 50 for 3" 2.0 Total Depth: 20.3 feet No groundwater or rock encountered 25 30 35 40 45 0 Earth Systems Consultants 1 Southwest 11 79-811 B Country Club Drive, Bermuda Dunes, CA 92201 Ph— 174ANSec_1 cce Vev-4-- Boring No: B$ Drilling Date: January 21, 1999 Project Name: Desert Cities Development at Hwy 111 and Washington Street Drilling Method: 6 -in. Hollow Stem Auger Project Number: 07074-01 Drill Type: CME 45 Boring Location: See Boring Location Plan Logged By: Cliff Batten Sample penetration o Cn N Description of Units Page 1 of 1 vType A Ri Resistance D E U ami ,� '2 " H Note: The stratification lines shown represent the P m o (Blows/6") to CL _ 5 2 oundbetween soild/or rock types Trend A A U and theapproximate transibtion may be gradational glow CountcDry Density —0 _ SILTY SAND: Tan, very dense, fine to very fine grained, dry 5 ■ 30/50 90.1 1.6 • — 10 ■ 22/50 — 15 50 for 5" 92.9 2.8 • — 20 50 for 5" 41 _ No groundwater encountered — 25 _X Rx WEATHERED GRANITE — 30 50 for 2" Total Depth: 30.2 feet — 35 —40 —45. Il� Earth Systems Con-tiltants Southwest 79-811 B Country Club Drive. Bermuda Dunes. CA 92201 Ph- /1fn%12141coo c♦v i- ,"•. Boring No: B6 Drilling Date: January 21, 1999 Project Name: Desert Cities Development at Hwy 111 and Washington Street Drilling Method: 6 -in. Hollow Stem Auger Project Number: 07074-01 Drill Type: CME 45 Boring Location: See Boring Location Plan Logged By: Cliff Batten Sample Type penetration rn Description of Units Page 1 of I ti c . Resistance E rUn e 0 Q A H c Note: The stratification lines shown represent the c> (Blows/6") ] .. z c approximate boundary between soil and/or rock types Graphic Trend A m' o i A U and the transition may be gradational. Blow Count Dry Density —0 _ snit SILTY SAND: Light brown, very dense, fine 50 for 2" grainedl, dry — 5 50 for 4" 100.2 0.7 _ SILTY SAND: Light brown, very dense, fine — 10 50 for 6"113.3 2.1 grainedl, dry to moist, with clay layers 84.4 34.1 — 1550 for 5" 96.4 4.2 – 91.1 22.3 Total Depth: 15.4 feet No groundwater or rock encountered — 20 - 25 — 30 — 35 —40 —45 0Earth Systems Con.ultants ` Southwest 79-811 B Country Club Drive, Bermuda Dunes. CA 92201 Ph— OAM 7nC_I cva Cn1—, 1 Boring No: B7 Drilling Date: January 21, 1999 Project Name: Desert Cities Development at Hwy 1 I 1 and Washington Street Drilling Method: 6 -in. Hollow Stem Auger Project Number: 07074-01 Drill Type: CME 45 Boring Location: See Boring Location Plan Logged By: Cliff Batten Sample Type penetration Description of Units Page I of I v ` U Resistance E rn ami -'• " ° Note: The stratification lines shown represent the P s n Y v >. � (Blows/6 A p, .y o == approximate boundary between soil and/or rock types Graphic Trend A A U and the transition may be gradational. Blow Count Dry Density Q SILTY SAND: Tan to light brown, very dense, fine 15/27/50 for 5" 0.4 to medium grained, dry 5 50 for 2" 0.6 10 , 42/50/50 0.5 15 50 for 3" 0.6 Total Depth: 15.3 feet No groundwater or rock encountered 20 25 30 — 35 —40 i —45 Desert Cities Development Project No: 07074-01 1 it :I i Fault Name or ii II Seismic Zone Reference Notes: (1) I - (2)_ i3)-_.... - �3) - `�3) -- 5 _....56).. San Andreas Fault System - Banning Table 1 NE I A ! 98 7.4 - Coachella Valley - FAULT PARAMETERS & NE i A j 95 7.4 DETERMINISTIC ESTIMATES OF MEAN PEAK GROUND ACCELERATION (PGA) ______ j 23 i Distance UBC Maximum Avg Avg Date of Largest Est mean (mi) & Fault Fault Magnitude Slip Return Last Historic Site Direction Type Length Mmax' Rate i Period Rupture Event PGA from Site (km) (Mw) (mm/yr) ! (yrs) (year) : >5.5M (year) _ (g) Reference Notes: (1) I - (2)_ i3)-_.... - �3) - `�3) -- 5 _....56).. San Andreas Fault System - Banning 15.5 NE I A ! 98 7.4 - Coachella Valley - j 5.5 NE i A j 95 7.4 - San Bernardino Mtn j 23 NW j A j 107 ; 7.3 - Whole S. Calif. Zone 5.5 NE 7.8 I 345 7.9 San Jacinto Fault System 354 6.3 1937 0.13 - Hot Spgs-Buck Ridge 17 SSW' C 70 6.5 - Anza Segment 20 SSW! A i 90 7.2 - Coyote Creek 22 SW B 40 6.8 - San Jacinto Valley 36 W B j 42 6.9 - Borrego Mtn 36 SSE j B 29 6.6 - Whole Zone i 20 SW 245 7.5 Mojave Faults 5,000 1992 7.3 i 0.12 Blue Cut 13 NNE B 30 I 6.8 Burnt Mtn 17 NNW • B i 20 ; 6.4 Eureka Peak 17 N ( B 19 6.4 Morongo 28 NW j C 23 6.5 Pinto Mountain 29 NNW B 73 7.0 S. Emerson -Copper Mtn. 32 NNE j B 54 6.9 Landers 32 NNW ! B 83 I 7.3 Bullion Mtn -Mesquite Lk. j 32 NE i B j 88 7.0 N. Johnson Valley 41 NNW I B 36 6.7 North Frontal Fault Z. (E) 43 NNW! B 27 6.7 Calico - Hidalgo 46 N i B i 95 ; 7.1 Elsinore Fault System ! 240 j 0.06 - Earthquake Valley 141 SSW B 20 6.5 - Julian Segment 43 SW I A 75 7.1 - Temecula Segment 47 WSW I B 42 6.8 - Whole Zone 43 SW i 250 7.5 Brawley Seismic Zone 41 ESE j B I 42 i 6.4 10 220 c. 1690 6.2 1986 0.44 25 I 220 c. 1690 6.5 1948. 0.44 24 433 0.16 --- --- 1857 7.8 1857. 0.52 2 354 6.3 1937 0.13 12 250 1918 6.8 1918 0.17 i 4 j 175 1968 6.5 1968 0.12 12 83 6.8 1899 0.08 j 4 ! 175 6.5 1942: 0.06 --- ; --- 0.20 1 762 0.19 0.6 5,000 1992 7.3 1992 0.12 0.6 5,000 1992 6.1 1992: 0.12 0.6 1,172 5.5 1947 0.08 2.5 499 0.11 0.6 5,000 0.09 0.6 j 5,000 1992 7.3 1992 j 0.12 0.6 5,000 j 0.09 0.6 j 5,000 i 0.06 0.5 i 1,727 I 0.07 0.6 I ; 5,000 ! 0.07 2 351 0.05 5 i 340 0.08 5 ! 240 j 0.06 --- j --- j 0.10 25 24 5.9 1981 i I 0.05 Notes: 1. Jennings (1994) and CDMG (1996) 2. CDMG (1996), where Type A faults, Mmax > 7 and slip rate >5 mm/yr, Type C faults, Mmax <6.5 and slip rate < 2 mm/yr. 3. WGCEP (1995), where: A - Type A (Characteristic), B - Type B, C- Type C 4. CDMG (1996) based on Wells & Coppersmith (1994) 5. Ellsworth Catalog in USGS PP 1515 (1990) and USBR (1976), Mw = moment magnitude, 6. The estimates of the mean Site PGA are based on the attenuation relationship of: Weighted average of Campbell & Bozorgnia; Boore, Joyner & Fumal; and Sadigh (1994) (mean plus sigma values are about 1.6 times higher) EARTH SYSTEMS CONSULTANTS SOUTHWEST sljnsag Iso L jo kmuzuznS S XIUNHddv 11 07074-01 Feb 12, 1999 PARTICLE SIZE ANALYSIS ASTM D-422 Job Name: Desert Cities 1 Sample ID: Boring #1 @ 0 - 5' J Soil Description Silty F to C. Sand with Gravel to 3/4" (SM) Particle Shape: Sub -Angular 1] SIEVE SIZE % PASSING '1 1-1/2" 100 100 l 3/4" 97 I .. 1/2" 93 3/8" 91 J #4 87 J #8 82 ']1 #16 80 #30 77 #50 68 #100 46 #200 27 %Gravel: 13 % Sand: 59 'J % Silt: 22 % Clay (3 micron): 5 07074-01 Feb. 12,1999 DIRECT SHEAR ASTM D 3080-90 (modified for unconsolidated, undrained conditions) Desert Cities Boring #1 @ 0-5' Silty F to C Sand (SM) Remolded @ 90% 1.4 1.2 1.0 0.8 co� rA rn 0.6 9 M 0.4 Initial Dry Density: 106.9 pcf Initial Mosture Content: 10.5 % Peak Friction Angle (0): 34° Cohesion (c): 0.019 Kg/cMA 2 (38 psf) SHEAR vs. NORMAL STRESS i,t - pdd w- 0.0 NORMAL STRESS, Kg1cm A 2 EARTH SYSTEMS CONSULTANTS SOUTHWEST I 07074-01 Feb. 12, 1999 DIRECT SHEAR continued ASTM D 3080-90 (modified for unconsolidated, undrained conditions) 11 Desert Cities 'Boring #1 @ 0-5' Silty F to C Sand (SM) Remolded @ 90% SPECIFIC GRAVITY: 2.67 (assumed) SAMPLE NO.: 1 2 3 4 AVERAGE INITIAL _l WATER CONTENT, % 10.5 10.5 10.5 10.5 10.5 ' 1 DRY DENSITY, pcf 106.9 106.9 106.9 106.9 106.9 SATURATION, % 50.2 50.2 50.2 50.2 50.2 �1 VOID RATIO 0.558 0.558 0.558 0.558 0.558 DIAMETER, inches 2.40 2.40 2.40 2.40 '0.000 0.00 0.00 0.00 0.00 AT TEST WATER CONTENT, % 23.3 23.2 23.3 23.3 23.3 SATURATION, % 111.6 110.9 111.6 111.2 111.3 8 oS 1.4 1.2 0.2 0.0 0.0000 0.0500 0.1000 0.1500 0.2000 HORIZONTAL DEFORMATION, inches EARTH SYSTEMS CONSULTANTS SOUTHWEST Il . 07074-01 Feb 12, 1999 MAXIMUM DENSITY / OPTIMUM MOISTURE ASTM D 1557-91 (Modified) J Job Name: Desert Cities Procedure Used: A Sample ID: Boring #1 @ 0-5' Prep. Method: Moist 11 Location: Native Rammer Type: Mechanical Description: Olive Brown Silty F to C Sand with Specific Gravity: 2.67 (assumed) Sieve Size % Retained 119 pcf 3/4" Density: 1�Maximum Optimum Moisture: r� 9.8 1� 140 -135 tj 1 130 125 1 �J [ 120 T--r--�� Sieve Size % Retained 119 pcf 3/4" 2.0 10.5% 3/8" 6.1 #4 9.8 5 10 15 20 25 30 Moisture Content, percent EARTH SYSTEMS CONSULTANTS SOUTHWEST