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04-3503 (CSCS) Geotechnical Engineering Report14 Earth Systems Southwest 7 Ob. LZ- 2 - 305- #WY a/ GEOTECHNICAL ENGINEERING REPORT PROPOSED PHASE 11 DEVELOPMENT THE CENTRE AT LA QUINTA LA QUINTA, CALIFORNIA -owl Consulting Engineers and Geologists the dMIOLL amici 1! STAMKO DEVELOPMENT 2205 NORTH POINSETTIA AVENUE 1 MANHATTAN BEACH, CALIFORNIA 90266 GEOTECHNICAL ENGINEERING REPORT PROPOSED PHASE H DEVELOPMENT THE CENTRE AT LA QUINTA LA QUINTA, CALIFORNIA .ti © 2002 Earth Systems Southwest -Unauthorized use or copying of this document is strictly prohibited without the express written consent of Earth Systems Southwest. „. File Nd',:W628-01 :P 02-04-803 ..z I � i. it It s Earth Systems �'+ Southwest . Apri13 0, 2002 Stamko Development 2205 North Poinsettia Avenue Manhattan Beach, California 90266 79-811B Country Club Drive Bermuda Dunes, CA 92201 (760)345-1588 (800)924-7015 FAX (760) 345-7315 File No.: 08628-01 02-04-803 Attention: Ms. Christine Clarke Project: Proposed Phase II Development of The Centre At La Quinta, La Quinta, California Subject: GEOTECHNICAL ENGINEERING REPORT - References: 1. Earth Systems Consultants Southern California, Geotechnical Feasibility Report, The Center at La Quinta, dated January 20, 1997, File No.: SS -6321-P1, Document No.: 96-12-721. M 2. Krazan & Associates, Inc., Geotechnical Engineering Investigation, Proposed Wal-Mart Store #1805-02, dated October 3, 2001, Project No.: 112-01081. y Dear Ms, Clarke: We take pleasure to present this Geotechnical Engineering Report prepared for the proposed Phase II development of The Centre at La Quinta to be located on the southeast corner of Highway 111 and La Quinta Centre Drive in the City of La Quinta, California. This report presents our findings and recommendations for site grading and foundation design, incorporating the iri$formation supplied to our office. The site is suitable for the proposed development provided the recommendations in this report are followed in design and construction. This report should stand as a whole, and no part of the report should be excerpted or used to the exclusion of any other part. This report completes our scope of services in accordance with our agreement, dated March 19, 2002 and authorized April 9, 2002. 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.. Unless requested in writing, the client is responsible to distribute this report to the appropriate governing agency or other members of the design team. We appreciate the opportunity to provide our professional services. Please contact our office if there are any questions or comments concerning this report or its recommendations. Respectfully submitted, EARTH SYSTEMS SOUTHWEST GFo �,�E1tE �ZCNa QPOFEss/D\ Karl A. Harmon * RG 7256 * CEG 221 Craig ill CE 38234 m CEG 2243 , CE 38 EXP. 03/31!05 JD SER/kah/csh/dac ' A'AJG 0� �P �� CML TFOF Distribution: 2/Stamko Development, 4/TKC, I/RCF11 ,F� SFO CAUf :. 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 2.2 Laboratory Testing...................................................................................................3 Section3 DISCUSSION.........................................................................................................4 3.1 Soil Conditions................................................................................:.......................4 3.2 Groundwater............................................................................................................4 3.3 Geologic Setting...................................................................... .................................4 3.4 Geologic Hazards.....................................................................................................5 3.4.1 Seismic Hazards...........................................................................................5 3.4.2 Secondary Hazards.........:.............................................................................6 -° 3.4.3 Site Acceleration and Seismic Coefficients.................................................7 EARTH SYSTEMS SOUTHWEST Section 4 CONCLUSIONS .............................. Section 5 RECOMMENDATIONS SITE .....................................................................................10 DEVELOPMENT AND GRADING .......................................................................10 -' 5.1 Site Development - Grading 5.2 ........10 Excavations and Utility Trenches ..........................................................................11 5.3 Slope Stability of Graded Slopes...........................................................................11 STRUCTURES................................................................................................................13 _..T .4 Foundations .......... ...................................................... 5.5 .................. ..........................13 Slabs-on-13rade ............................ ...................................................: .........14 ............ 5.6 Retaining Walls......................................................................................................15 5.7 Mitigation of Soil Corrosivity on Concrete 5.8 ...........................................................16 Seismic Design Criteria 5.9 ............... Pavements .......................................................................................................0. ' Section 6 LIMITATIONS AND ADDITIONAL SERVICES 6.1 ..........................................19 Uniformity of Conditions and Limitations .............................................................19 6.2 Additional Services..................................................................... .......................... .20 REFERENCES ............................... APPENDIX A Site Location Map Boring Location Map Table 1 Fault Parameters 2000 International Building Code (IBC) Seismic Parameters ' Logs of Borings APPENDIX B Laboratory Test Results EARTH SYSTEMS SOUTHWEST r 1 _J April 30, 2002 Section 1 INTRODUCTION 1.1 Project Description -1- File No.: 08628-01 02-04-803 This Geotechnical Engineering Report has been prepared for the proposed Phase II development of The Centre at La Quinta to be located on the southeast corner of Highway I l 1 and La Quinta Centre Drive in the City of La Quinta, California. Theproposed retail shopping center will include an approximately 225,000 square feet Wal Mart Store, an 86,584 square feet retail store (unnamed), a 19,200 square feet building for miscellaneous shops, a gas station and six parcels for future development. We assume that the proposed Wal Mart Store will be of concrete tilt -up or masonry block construction while the other retail buildings and shops may be constructed of masonry or wood frame and stucco and will be supported by conventional shallow continuous or pad footings. Site development will include site grading, building pad preparation, underground utility installation, street and parking lot. construction, and concrete driveway and sidewalk placement. Based on existing site topography, site grading may include cuts and fills up to 10 to 15 feet. We used maximum column loads of 3000 kips and a maximum wall loading of 2 kips per linear foot as a basis for the foundation recommendations. All loading is assumed to be dead plus actual live load. If actual structural loading exceeds these assumed values, we would need to reevaluate the given recommendations. 1.2 Site Description The approximately 40 -acre project site is an irregular shaped parcel located east of La Quinta Centre Drive and south of Highway 111 in the City of La Quinta, California. The site location and vicinity are shov'm on Figure 1 in Appendix A. I Currently the site consists of vacant land with a moderate growth of native desert brush and weeds. The northern portion of the site is relatively flat while the southern portion of the site is hummocky, controlled by small vegetation induced sand dunes. A large sand dune is located near the south east corner of the site with up to 25 feet of relief and very dense mesquite growth on the leeward side (east). An existing concrete slab. and miscellaneous masonry walls are located on the top of a large sand dune (15 to 20 feet) in the northeast portion of the site. Scattered miscellaneous trash and debris was noted throughout the site with heavier concentrations of trash including some 55 -gallon drums near the southeast corner of the site. A temporary retention basin for storm water drainage from the development to the west has been constructed in the southwest portion of the site and does encroach within the proposed Wal Mart pad. Drainage of the site is accomplished through surface infiltration and sheet flow. Site elevation is approximately 60 feet above sea level. The project site is bounded to the north by Highway 111, to the east by a row of date palm trees and vacant land and to the south by vacant land. La Quinta Centre Drive defines the western boundary of the site with an existing auto dealership adjacent to the northern portion and a vacant graded pad along the southern portion of the site. EARTH SYSTEMS SOUTHWEST i April 30, 2002 - 2 - File No.: 08628-01 _.! 02-04-803 The history of past site uses and development of the subject property was not investigated as part of our scope of services. Some evidence of limited past development was observed on the site during our reconnaissance. Buried remnants such as old foundations, pavements or septic systems from past development may exist on the site. There may be underground utilities located near and within the proposed building areas. These utility lines may include but are not limited to domestic water, electric, sewer, and gas. 1.3 Purpose and Scope of Work The purpose for our services was to evaluate the site soil conditions and to provide professional ro 1 opinions and recommendations regarding the proposed development of the site. The scope of work included the following: ➢ A general reconnaissance of the site. a ➢ Shallow subsurface exploration by drilling 5 exploratory borings to depths ranging from 21.5 to 31.5 feet. - ➢ Laboratory testing of selected soil samples obtained from the exploratory borings. ➢ Review of selected published technical literature pertaining to the site and previous geotechnical reports prepared for 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: t�t ➢ Discussions on subsurface soil and groundwater conditions. t ➢ Discussions on regional and local geologic conditions. ➢ Discussions on geologic and seismic hazards. ➢ Graphic and-4abulated results of laboratory tests and field studies. ➢ Recommendations regarding: • Site development and grading criteria, • Excavation conditions and buried utility installations, s' Structure foundation type and'desi 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. ➢ Ari 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 1� 1� April 30, 2002 -3 - File No.: 08628-01 02-04-803 Section 2 METHODS OF INVESTIGATION 2.1 Field Exploration Five exploratory borings were drilled to depths ranging from 21.5 to 31.5 feet below the existing ground surface to observe the soil profile and to obtain samples for laboratory testing. The borings were drilled on April 16, 2002 using 8 -inch outside diameter hollow -stem augers, and 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 rope and cathead activated manual hammer dropping 30 inches in general accordance with ASTM D 1586. Recovered soil samples were sealed in containers and returned to the laboratory. Bulk samples were also obtained from auger cuttings, representing a mixture of soils encountered at the depths noted. The final logs of the borings represent our interpretation of the contents of the field logs and the results of laboratory testing performed on the samples obtained during the subsurface 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 include soils that would be exposed and used during grading, and those deemed to be within the influence of the proposed structure. Test results are presented in graphic and tabular form in Appendix B of this report. The tests were conducted in general accordance with the procedures of the American Society for Testing and Materials (ASTM) or other standardized methods as referenced below. Our testing program consisted of the following: ➢ In-situ Moisture Content and Unit Dry Weight for the ring samples (ASTM D 2937). ➢ Maximum density tests were performed to evaluate the moisture -density relationship of typical soils encountered (ASTM D 1557-91). ➢ 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) to evaluate the potential adverse effects of the soil on concrete and steel. EARTH SYSTEMS SOUTHWEST P' April 30, 2002 - 4 - File No.: 08628-01 02-04-803 Section 3 DISCUSSION 3.1 Soil Conditions The field exploration indicates that site soils consist generally of interbedded layers of loose to medium dense, dry to damp Silty Sand, Sandy Silt and Sand (SM, ML, SP -SM). The boring logs provided in Appendix A include more detailed descriptions of the soils encountered. The surface soils are visually classified to be in the very low expansion category in accordance with Table 18A -I -B of the 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. Consolidation tests indicate 0.8 to 1.3 percent collapse upon inundation and is considered a moderate 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 1 landscaping, or hardscape normally mitigates this hazard. 3.2 Groundwater Free groundwater was not encountered in the borings during exploration. The depth to l_ groundwater in the area is believed to be greater than 100 feet. Groundwater levels may fluctuate with precipitation, irrigation, drainage, regional pumping from wells, and site grading. The :i absence of groundwater levels detected may not represent an accurate or permanent condition. f 1 ' 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 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 j' Mountains on the southwest. These mountains expose primarily Precambrian metamorphic and f 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. i EARTH SYSTEMS SOUTHWEST -t April 30, 2002 - 7 - .File No.: 08628-01 02-04-803 subsidence is dependent on relative density of the soil, groundshaking (cyclic shear strain), and earthquake duration (number of strain cycles). Uncompacted fill areas may be susceptible to seismically induced settlement. Slope Instability: The site is relatively flat. Therefore, potential hazards from slope instability, landslides, or debris flows are considered negligible. Flooding: The project site does not lie within a designated FEMA 100 -year flood plain. The ( project site may be in an area where sheet flooding and erosion could occur. If significant changes are proposed for the site, appropriate project design, construction, and maintenance can minimize the site sheet flooding potential. e. 3.4.3 Site Acceleration and Seismic Coefficients - Site Acceleration: The potential intensity of ground motion may be estimated 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 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 peak acceleration (EfA) is used in structural design. The following table provides the probabilistic estimate of the PGA and EPA taken from the 1996 CDMG/USGS seismic hazard maps. r"I : EARTH SYSTEMS SOUTHWEST April 30, 2002 Estimate of PGA and EPA from 1996 CDMG/USGS Probabilistic Seismic Hazard Manc File No.: 08628-01 02-04-803 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 0.3 seconds divided by 2.5 for 5% damping, as defined by the Structural Engirieers Association of California (SEAOC, 1996). 1997 UBC Seismic Coefficients: The Uniform Building Code (UBC) 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 UBC design. The following lists the -' seismic and site coefficients given in Chapter 16 of the 1997 Uniform Building Code (UBC). 1997 UBC Seismic Coefficients for Chapter 16 Seismic Provisions Seismic Zone: Seismic Zone Factor, Z: Soil Profile Type: Seismic Source Type: Closest Distance to Known Seismic Source Near Source Factor, Na: Near Source Factor, Nv: Seismic Coefficient, Ca: Seismic Coefficient, Cv: 4 0.4 SD A 8.7 km = 5.4 miles 1.05 1.30 0.46 = 0.44Na 0.83 = 0.64Nv Reference Figure 16-2 Table 16-I Table 16-J Table 16-U (San Andreas Fault) Table 16-S Table 16-T Table 16-Q Table 16-R Seismic ZoninZ: The Seismic Safety Element of the 1984 Riverside County General Plan establishes groundshaking hazard zones. The project area is mapped in Ground Shaking Zone V. Ground Shaking Zones are based on distance from causative faults and underlying soil types. The site does not lie within the Liquefaction Hazard area established by this Seismic Safety Element. These groundshaking hazard zones are used in deciding suitability of land use. 2000 IBC Seismic Coefficients: For comparative purposes, the newly released 2000 International Building Code (IBC) seismic and site coefficients are given in "Appendix A. As of the issuance of this report, we are unaware when governing jurisdictions may adopt or modify the IBC provisions. EARTH SYSTEMS SOUTHWEST Risk Equivalent Return Period (years) PGA Approximate EPA Rk 10% exceedance in 50 years 475 0.52 0.46 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 0.3 seconds divided by 2.5 for 5% damping, as defined by the Structural Engirieers Association of California (SEAOC, 1996). 1997 UBC Seismic Coefficients: The Uniform Building Code (UBC) 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 UBC design. The following lists the -' seismic and site coefficients given in Chapter 16 of the 1997 Uniform Building Code (UBC). 1997 UBC Seismic Coefficients for Chapter 16 Seismic Provisions Seismic Zone: Seismic Zone Factor, Z: Soil Profile Type: Seismic Source Type: Closest Distance to Known Seismic Source Near Source Factor, Na: Near Source Factor, Nv: Seismic Coefficient, Ca: Seismic Coefficient, Cv: 4 0.4 SD A 8.7 km = 5.4 miles 1.05 1.30 0.46 = 0.44Na 0.83 = 0.64Nv Reference Figure 16-2 Table 16-I Table 16-J Table 16-U (San Andreas Fault) Table 16-S Table 16-T Table 16-Q Table 16-R Seismic ZoninZ: The Seismic Safety Element of the 1984 Riverside County General Plan establishes groundshaking hazard zones. The project area is mapped in Ground Shaking Zone V. Ground Shaking Zones are based on distance from causative faults and underlying soil types. The site does not lie within the Liquefaction Hazard area established by this Seismic Safety Element. These groundshaking hazard zones are used in deciding suitability of land use. 2000 IBC Seismic Coefficients: For comparative purposes, the newly released 2000 International Building Code (IBC) seismic and site coefficients are given in "Appendix A. As of the issuance of this report, we are unaware when governing jurisdictions may adopt or modify the IBC provisions. EARTH SYSTEMS SOUTHWEST F April 30, 2002 - 9 - File No.: 08628-01 02-04-803 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: `..J ➢ 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 8.7 km from a Type A seismic source ce as defined in the Uniform Building Code. A qualified professional should design any permanent structure constructed on the site. The minimum seismic design should comply with the latest edition of the Uniform 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, fld tiding, 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. ➢ 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 loose to medium dense and are unsuitable in their present condition to support structures, fill, and hardscape. The soils within the building and structural areas will require moisture conditioning, over excavation, and recompaction to improve bearing capacity and reduce settlement from static loading. Soils can be readily cut by normal grading equipment. ➢ The native soils exhibit a very severe potential for metal loss from electrochemical corrosion processes. A qualified corrosion engineer should be consulted regarding mitigation of the corrosive effects of site soils on metals. IEARTH SYSTEMS SOUTHWEST April. 30, 2002 _10- File No.: 08628-01 02-04-803 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 prior to placing fill. Local variations in soil conditions may warrant increasing the depth of recompaction and over -excavation. Clearing and Grubbing: Prior to site grading existing vegetation, trees, large roots, pavements, foundations, non -engineered fill, construction debris, trash, abandoned underground utilities and . other deleterious materials 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. Building Pad Preparation: Because of the relatively non-uniform and under -compacted nature of the majority of the site soils, we recommend recompaction of soils in the building area. The existing surface soils within the building pad and foundation areas should be over -excavated to a minimum of 48 inches below the base footing level. The over -excavation should extend for 5 feet beyond the outer edge of exterior footings. Areas• requiring fill should be over -excavated as outlined below. The bottom of the overcavations should be observed by a representative of ESSW prior to processing and filling. If unsatisfactory conditions are observed at the bottom of the overxcavation such as dry silt layers, root laden soils or other detrimental conditions, additional removals may be required. The bottom of the sub -excavation should be scarified; moisture conditioned, and recompacted to at least 90 % relative compaction (ASTM D 1557) for an additional depth of 12 inches. These recommendations are intended to provide a minimum of 48 inches of moisture conditioned and compacted soil beneath the floor slabs and footings. • Fill Areas: The areas to receive structural fill should be initially prepared by removing organic growth from the pad surface and other existing improvements. These areas should then be moisture conditioned by the use of sprinklers or rain birds to a depth of 4 to 5 feet below existing �., grade. The surface should be thoroughly rolled with loaded scrapers to achieve at least 90% of maximum dry density in the upper 3 feet of original grade. The depth of moisture penetration and compactive effort should be verified by testing. If the contractor is unable to achieve the .desired compaction at depth from the surface, removal and recompaction may be necessary. The actual limits of these areas should be determined in the field at the time of grading. Auxiliary Structures Subgrade Pre aration• Auxiliary ln' p structures such as garden or retaining walls should have the foundation subgrade prepared similar to the building pad recommendations given above. The lateral extent of the over -excavation needs only to extend 2 feet beyond the face of the footing. Subgrade Preparation: In areas to receive fill, pavements, or hardscape, the subgrade should be scarified; . moisture conditioned, and compacted to at least 90% relative compaction EARTH SYSTEMS SOUTHWEST , . ] .1 , 1. , April 30, 2002 - 11 - File No.: 08628-01 02-04-803 (ASTM D 1557) for a depth of 12 inches below finished subgrades. Compaction should be verified by testing. Engineered Fill Soils: The native soil is suitable for use as engineered fill and utility trench backfill provided it is free of significant organic or deleterious matter. The native soil should be t. laced in maximum 8 -inch lifts loose and compacted to at 1 ° P (loose) p east 90 /o 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 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 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 71 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 -.1 (ASTM D 1557) near optimum moisture content. Shrinkage: The shrinkage factor for earthwork is expected to range from 15 to 30 percent for the upper excavated or scarified site soils. This estimate is based on compactive effort to achieve an average relative compaction of about 92% and may vary with contractor methods. Subsidence is estimated to range from 0.1 to 0.2 feet. Losses from site clearing and removal of existing site improvements may affect earthwork quantity calculations and should be considered. Site Drainage: Positive drainage should be maintained away from the structures (5% for 5 feet minimum) to prevent ponding and subsequent saturation of the foundation soils. Gutters and z 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 '4 pond on or near pavgd areas. 5.2 Excavations and Utility Trenches Excavations should be made in accordance with CalOSHA requirements. Our site exploration and knowledge of the general area indicates there is a potential for caving of site excavations (utilities, footings, etc.). Excavations within sandy soil should be kept moist, but not saturated, to reduce the potential of caving or sloughing. Where excavations over 4 feet deep are planned, lateral bracing or appropriate cut slopes of 1.5:1 (horizontal:vertical) should be provided. No surcharge loads from stockpiled soils or construction materials should be allowed within a horizontal distance measured from the top of the excavation slope, equal to the depth of the excavation. Utility Trenches: Backfill of utilities within road or public right-of-ways should be placed in conformance with the requirements of the governing agency (water district, public works department, etc.) Utility trench backfill within private property should be placed in conformance with the provisions of this report. In general, service lines extending inside of property may be backfilled with native soils compacted to a minimum of 90% relative compaction. Backfill operations should be observed and tested to monitor compliance with these recommendations. 5.3 Slope Stability of Graded Slopes EARTH SYSTEMS SOUTHWEST i April 30, 2002 -12- File No.: 08628-01 j 02-04-803 :r Unprotected, permanent graded slopes should not be steeper than 3:1 (horizontal:vertical) to reduce wind and rain erosion. Protected slopes with ground cover may be as steep as 2:1. However, maintenance with motorized equipment may not be possible at this inclination. Fill slopes should be overfilled and trimmed back to competent material. Slope stability calculations are not presented because of the expected minimal slope heights (less than 5 feet). I 1 --�1 EARTH SYSTEMS SOUTHWEST April 30, 2002 -13- File No.: 08628-01 02-04-803 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 prior to placement of reinforcing steel or concrete. Any loose soil or construction debris should be removed from footing excavations prior to placement of concrete. Conventional Spread Foundations: Allowable soil bearing pressures are given below for q') 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 E Allowable increases of 300 psf per each foot of additional footing width and 300 psf for each } additional 0.5 foot of footing depth may be used up to a maximum value of 3000 psf. ➢ Isolated pad foundations, 2 x 2 foot minimum in plan and 18 inches below grade: 2000 psf for dead plus design live loads Allowable increases of 200 psf per each foot of additional footing width and 400 psf for each -� additional 0.5 foot of footing depth may be used up to a maximum value of.3000 psf. A one-third (1/3) increase in the bearing pressure may be used when calculating resistance to wind or seismic loads. The allowable .bearing. values indicated are based on the anticipated maximum loads stated in Section 1.1 of this report. If the anticipated loads exceed these values, the geotechnical engineer must reevaluate the allowable bearing values and the grading requirements. Minimum reinforcement for continuous wall footings should be 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, 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, 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 EARTH SYSTEMS SOUTHWEST April 30, 2002 -14- File No.: 08628-01 02-04-803 resistance and frictional resistance may be used in combination if the friction coefficient is J reduced to 0.23 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. Lateral passive resistance is based on M7 the assumption that any required backfill adjacent to foundations is properly compacted. 5.5 Slabs -on -Grade Subgrade: Concrete slabs -on -grade and flatwork should be supported by compacted soil placed in accordance with Section 5.1 of this report. Vapor Barrer: In areas of moisture sensitive floor coverings, an appropriate vapor barrier should t be installed to reduce moisture transmission from the subgrade soil to the slab. For these areas an impermeable membrane (10 -mil moisture barrier) should underlie the floor slabs. The membrane should be covered with 2 inches of sand to help protect it during construction and to aide in concrete curing. The sand should be lightly moistened just prior to placing the concrete. Low -slump concrete should be used to help reduce the potential for concrete shrinkage. The effectiveness of the moisture barrier is dependent upon its quality, method of overlapping, its protection during construction, and the successful sealing of the barrier around utility lines. Slab thickness and reinforcement: Slab thickness and reinforcement of slabs -on -grade are contingent on the recommendations of the structural engineer or architect and the expansion index of the supporting soil. Based upon our findings, a modulus of subgrade reaction of approximately 200 pounds per cubic inch can be used in concrete slab design for the expected very low expansion subgrade. Concrete slabs and flatwork should be a minimum of 4 inches thick (actual, not nominal). We suggest that the concrete slabs be reinforced with a minimum of No. 3 rebars at 18 -inch centers, i both horizontal directions, placed at slab mid -height to resist swell forces and cracking. Concrete floor slabs may either be monolithically placed with the foundations or doweled after footing placement. The thickness and reinforcing given are not intended to supersede any structural w requirements provided by the structural engineer. The project architect or geotechnical engineer should continually observe all reinforcing steel in slabs during placement of concrete to check for proper location within the slab. Control Joints: Control joints should be provided in all concrete slabs -on -grade at a maximum spacing of 36 times the slab thickness (12 feet maximum on -center, each way) as recommended by American Concrete Institute (ACI) guidelines. All joints should form approximately square patterns to reduce the potential for randomly oriented, contraction cracks. Contraction joints in the slabs should be tooled at the time of the pour or saw cut (1/4 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. Curing and Quality Control: The contractor should take precautions to reduce the potential of curling of slabs in this and desert region using proper batching, placement, and curing methods. F EARTH SYSTEMS SOUTHWEST i April 30, 2002 -15- File No.: 08628-01 02-04-803 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 Retaining Walls The following table presents lateral earth pressures for use in retaining wall design. The values are given as equivalent fluid pressures without surcharge loads or hydrostatic pressure.- Lateral ressure: Lateral Pressures and Sliding Resistance Granular Backfill Passive Pressure 375 pef -level ground Active Pressure (cantilever walls) 35 pcf - level ground Use when wall is permitted to rotate 0.1% of wall height At -Rest Pressure restrained walls 55 pcf - level ground Dynamic Lateral Earth Pressure 2 Acting at mid height of structure, 2511 psf Where H is height of backfill in feet Base Lateral Sliding Resistance Dead load x Coefficient of Friction: 0.50 Notes: 1. These values are ultimate values. A factor of safety of 1.5 should be used in stability analysis except for dynamic earth pressure where a factor of safety of 1.2 is acceptable. 2. Dynamic pressures are based on the Mononobe-Okabe 1929 method, additive to active earth pressure. Walls retaining less than 6 feet of soil need not consider this increased pressure. Upward sloping backfill or surcharge loads from nearby footings can create larger lateral pressures. Should Xany walls be considered for retaining sloped backfill or placed next to foundations, our office should be contacted for recommended design parameters. Surcharge loads should be considered if they exist within a zone between the face of the wall and a plane projected 45 degrees upward from the base of the wall. The increase in lateral earth pressure should be taken as 35% of the surcharge load within this zone. Retaining walls subjected to traffic loads should include a uniform surcharge load equivalent to at least 2 feet of native soil. Drainage: A backdrain or an equivalent system of backfill drainage should be incorporated into the retaining wall design. Our firm can provide construction details when the specific application is determined. Backfill immediately behind the retaining structure should be a free -draining granular material. In this case the native soils are considered free draining. Waterproofing should be according to the designer's specifications. Water should not be allowed to pond near the top of the wall. To accomplish this, the final backfill grade should be such that all water is diverted away from the retaining wall. Backfill and Subgrade Compaction: Compaction on the retained side of the wall within a horizontal distance equal to one wall height should be performed by hand -operated or other lightweight compaction equipment. This is intended to reduce potential locked -in lateral pressures caused by compaction with heavy grading equipment. Foundation subgrade preparation should be as specified in Section 5.1. EARTH SYSTEMS SOUTHWEST I i April 30, 2002 -16- File No.: 08628-01 02-04-803 ti 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 and low chloride ion concentration. 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 does not require any special provisions for concrete for these low concentrations as tested. Normal concrete mixes may be used. e..:l A minimum concrete cover of three (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. Electrical resistivity testing of the soil suggests that the site soils may present a very severe J 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. A qualified corrosion engineer should be consulted regarding mitigation of the corrosive effects of site soils on metals. 5.8 . Seismic Design Criteria This site is subject to strong ground shaking due to potential fault movements along the . > San Andreas and San Jacinto Faults. Engineered design and earthquake -resistant construction increase safety and allow development of seismic areas. The minimum seismic design should comply with the latest edition of the Uniform Building Code for Seismic Zone 4 using the seismic coefficients given in the table below. 1997 UBC Seismic Coefficients for Chapter 16 Seismic Provisions 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) Period of motion of the structure, (4) Soil -structure interaction, EARTH SYSTEMS SOUTHWEST Reference Seismic Zone: 4 Figure 16-2 Seismic Zone Factor, Z: 0.4 Table 16-I Soil Profile Type: SD Table 16-J Seismic Source Type: A Table 16-U Closest Distance to Known Seismic Source: 8.7 km = 5.4 miles (San Andreas Fault) Near Source Factor, Na: 1.05 Table 16-5 Near Source Factor, Nv: 1.30 Table 16-T ' Seismic Coefficient, Ca: 0.46 = 0.44Na Table 16-Q Seismic Coefficient, Cv: 0.83 = 0.64Nv Table 16-R 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) Period of motion of the structure, (4) Soil -structure interaction, EARTH SYSTEMS SOUTHWEST Aprii 30, 2002 -17- File No.: 08628-01 02-04-803 :,....t (5) Total resistance capacity of the system, (6) Redundancies, (7) Inelastic load -deformation behavior, and (8) Modification of damping and effective period as structures behave inelastically. Factors 5 to 8 are included in the structural ductility factor (R) that is 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 a minimum design. The owner and the designer should evaluate the level of risk and performance that is acceptable. Performance based criteria could be set in the design. The design engineer 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. 5.9 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 foi the pavements. Maintenance of proper drainage is necessary to prolong the service life of the pavements. Water should not pond on or near paved areas. The following table provides our preliminary recommendations for pavement sections. Final pavement sections recommendations should be based on design traffic indices and R -value tests conducted during grading after actual subgrade soils are exposed. EARTH SYSTEMS SOUTHWEST April 30, 2002 -18- File No.: 08628-01 02-04-803 PRELIMINARY RECOMMENDED PAVEMENTS SECTIONS R -Value Submde Soils - 50 (assumed) Mecism Methnd — CALTR ANC 1995 Traffic Index (Assumed) Pavement Use 1 Flexible Pavements Rigid Pavements Asphaltic Concrete Thickness (Inches) Aggregate Base Thickness (Inches) Portland Cement Concrete (Inches) Aggregate Base Thickness (Inches) 4.0 Auto Parking Areas 2.5 4.0 4.0 4.0 5.0 Driveways 3.0 4.0 5.0 4.0 6.0 Small Delivery Trucks 3.5 4.0 6.0 4.0 7.0 Semi -Type Trucks A 4.0 4.5 7.0 6.0 8.0 Semi -Type. Trucks B 4.5 5.5 8.0 6.0 )votes: 1. Asphaltic concrete should be Caltrans, Type B, 1/2 -in. or 3/4 -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 e i ' ' April, 30, 2002 -19- Section 6 LIMITATIONS AND ADDITIONAL SERVICES 6.1 Uniformity of Conditions and Limitations File No.: 08628-01 02-04-803 J 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 f groundwater may require additional studies, consultation, and possible revisions to our v recommendations. Findings of this report are valid as of the issued date of the report. However, changes in conditions of a property can occur with passage of time whether they are from natural processes or works of man on this or adjoining properties. In addition, changes in applicable standards occur whether they result from legislation or broadening of knowledge. Accordingly, findings of this report may be invalidated wholly or partially by changes outside our control. Therefore, this report is subject to review and should not be relied upon after a period of one year. t 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 take the necessary steps to see that the general contractor and all subcontractors follow such recommendations. It is further understood that the owner or the owner's representative is responsible for submittal of this report to the appropriate governing agencies. As the Geotechnical Engineer of Record for this project, Earth Systems Southwest. (ESSW) has striven to provide our services in accordance with generally accepted geotechnical engineering practices in this locality at this time. No warranty or guarantee is express or implied. This report was prepared for the exclusive use of the Client and the Client's authorized agents. ESSW should be provided the opportunity for a general review of final design and specifications in order that earthwork and foundation recommendations may be properly interpreted and implemented in the design and specifications. If ESSW is not accorded the privilege of making this recommended review, we can assume no responsibility for misinterpretation of our recommendations. Although available through ESSW, the current scope of our services does not include an environmental assessment, or investigation for the presence or absence of wetlands, hazardous or toxic materials in the soil, surface water, groundwater or air on, below, or adjacent to the subject property. EARTH SYSTEMS SOUTHWEST April 30, 2002 -20- File No.: 08628-01 02-04803 6.2 Additional Services This report is based on the assumption that an adequate program of client consultation, construction monitoring, and testing will be performed during the final design and construction phases to check compliance with these recommendations. Maintaining ESSW as the geotechnical consultant from beginning to end of the project will provide continuity of services. The geotechnical engineering firm providing tests and observations shall assume the responsibility of Geotechnical Engineer of Record. Construction monitoring and testing would be additional services provided by our firm. The costs of these services are not included in our present fee arrangements, but can be obtained from our office. The recommended review, tests, and observations include, but are not necessarily limited to the following: • Consultation during the final design stages of the project. • Review of the building and grading plans to observe that recommendations of our report have been properly implemented into the design. • Observation and testing during site preparation, grading and placement of engineered fill as required by UBC Sections 1701 and 3317 or local grading ordinances. • ' Consultation as required during construction. -000- ,Appendices as cited,,are attached and complete this report. EARTH SYSTEMS SOUTHWEST i April 30, 2002 -21- File No.: 08628-01 - 02-04-803 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. American Society of Civil Engineers (ASCE), 2000, ASCE Standard 7-98, Minimum Design Loads for Buildings and Other Structures. Blake, B.F., 2000, FRISKSP v. 4.00, A Computer Program for the Probabilistic Estimation of Peak Acceleration and. Uniform Hazard Spectra Using 3-D Faults as Earthquake Sources, Users Manual. 1 California Department of Conservation, Division of Mines and Geology (CDMG), 1997, Guidelines for Evaluating and Mitigating Seismic Hazards in California, Special Publication 117. California Department of Water Resources, 1964, Coachella Valley Investigation, Bulletin No. 108, ::..� 146 pp. Department of Defense, 1997, Soil Dynamics and* Special Design Aspects, MIL-HDBK-1007/3, superseding NAVFAC DM 7.3. r a Department of the Navy, Naval Facilities Engineering Command (NAVFAC), 1986, Foundations } and Earth Structures, NAVFAC DM 7.02. Envicom Corporation and the County of Riverside Planning Department, 1976, Seismic Safety and Safety General Plan Elements Technical Report, County of Riverside. Ellsworth, W.L., 1990, "Earthquake History, 17694989" in: The San Andreas Fault System, California: U.S. Geological Survey Professional Paper 1515, 283 p. Federal Emergency Management Agency (FEMA), 1997, NEHRP Recommended Provisions for Seismic Regulations for New Buildings and Other Structures, Part 1 — Provisions and Part 2- Commentary. Hart, E.W., 1994, Fault -Rupture Hazard Zones in California: California Division of Mines and Geology Special Publication 42, 34 p. International Conference of Building Officials, 1997, Uniform Building Code, 1997 Edition. International Conference of Building Officials, 2000, International Building Code, 2000 Edition. Jennings, C.W, 1994, Fault Activity Map of California and Adjacent Areas: California Division of Mines and Geology, Geological Data. Map No. 6, scale 1:750,000. i EARTH SYSTEMS SOUTHWEST April 30, 2002 -22- File No.: 08628-01 02-04-803 Petersen, M.D., Bryant, W.A., Cramer, C.H., Cao, T., Reichle, M.S., Frankel, A.D., Leinkaemper, - J.J., McCrory, P.A., and Schwarz, D.P., 1996, Probabilistic Seismic Hazard Assessment for the State of California: California Division of. Mines and Geology Open -File Report 96-08. Proctor, R. J., 1968, Geology of the Desert Hot Springs - Upper Coachella Valley Area, California Division of Mines and Geology, DMG Special Report 94. Reichard, E.G. and Mead, J.K., 1991, Evaluation of a Groundwater Flow and Transport Model of the Upper Coachella Valley, California, U.S.G.S. Open -File Report 91-4142. Riverside County Planning Department, 1984, Seismic Safety Element of the Riverside County General Plan, Amended. Rogers, T.H., 1966, Geologic Map of California - Santa Ana Sheet, California Division of Mines and Geology Regional Map Series, scale 1:250,000. 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. B1, January 10, 1989, pp. 603-623. ` . Structural Engineers Association of California (SEAOC), 1996, Recommended Lateral Force Requirements and Commentary. ' Tokimatsu, K, and Seed, H.B., 1987, Evaluation of Settlements in Sands Due To Earthquake Shaking, ASCE, Journal of Geotechnical Engineering, Vol. 113, No. 8, August 1987. Van de Kamp, P.C., 1973, Holocene 'Continental Sedimentation m the Salton Basin, California: A ReconnaissarWe, 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. Wallace, R. E., 1990, The San Andreas Fault System, California: U.S. Geological Survey • Professional Paper 1515, 283 p. EARTH SYSTEMS SOUTHWEST d APPENDIX A Site Location Map 9 Boring Location Map Table 1 Fault Parameters 2000 International Building Code (IBC) Seismic Parameters Logs of Borings .! y �i - Y.�1 EARTH SYSTEMS SOUTHWEST Mei g Si -4 x C1 2002 63 1 o b e 1 c- r e r Ai rNici toU SA Mei g Si -4 5Z f3 The Centre at (,a Quinta 08628-01 Table 1 Fault Parameters & & Detprminictir Retimatpc of Maw., Pool. !_. A......r­ "C '. fnn Bi] Fault Name or Seismic Zone Distance from Site (mi) (km) Fault Type UBC Maximum Magnitude Mmax (Mw) Avg Slip Rate (mm/yr) Avg Return Period (yrs) Fault Length (km) Date of Last Rupture (year) Largest Historic Event >5.5M (year) Mean site PGA, g (g) Reference Notes: 1 2 3 4 2 2 2 5 6 San Andreas - Southern (C V +S B M) 5.4 8.7 SS A 7.4 24 220 203 c. 1690 0.43 . San Andreas - Banning Branch 5.7 9.1 SS A 7.1 10 220 98 6.2 1986 0.38 San Andreas - Mission Crk. Branch 5.7 9.1 SS A 7.1 25 220 95 6.5 1948 038 Blue Cut 1 14.0 22.5 SS C 6.8 1 760 30 -- 0.17 San Jacinto (Hot Spgs - Buck Ridge) 17.2 27.7 SS. C 6.5 2 354 70 6.3 1937 0.11 Burnt Mtn. 17.3 27.9 SS B 6.4 0.6 5000 20 1992 6.1 1992 0.11 Eureka Peak 18.2 29.3 SS B 6.4 0.6 5000 19 1992 6.1 1992 0.10 San Jacinto-Anza 21.6 34.7 SS A 7.2 12 250 91 5.5 1928 0.14 San Jacinto -Coyote Creek 21.9 35.3 SS B 6.8 4 175 41 1968 6.5 1968 0.11 Morongo 28.7 46.3 SS C 6.5 0.6 1170. 23 5.5 1947 0.07 Pinto Mountain 30.2 48.7 SS B 7.0 2.5 499 73 0.09 Emerson So. - Copper Mtn. 31.5 50.8 SS B 6.9 0.6 5000 54 0.08 Landers 32.4 52.2 SS B 7.3 0.6 5000 83 1992 7.3 1992 0.10 Pisgah -Bullion Mtn. -Mesquite Lk 33.6 54.1 SS B 7.1 0.6 5000 88 1999 7.1 1999 0.08 San Jacinto - Borrego 35.4 56.9 SS B 6.6 4 175 29 6.5 1942 0.06 San Jacinto -San Jacinto Valley 36.7 59.1 SS B 6.9 12 83 43 6.8 1918 0.07 North Frontal Fault Zone (East) 38.5 62.0 DS B 6.7 0.5 1727 27 0.07 Earthquake Valley 40.3 64.8 SS B 6.5 2 351 20 0.05 Brawley Seismic Zone 41.3 66.5 SS B 6.4 25 24 42 5.9 1981 0.04 Johnson Valley (Northern) 43.2 69.5 SS B 6.7 0.6 5000 36 1992 7.3 1992 0.05 Elsinore -Julian 44.3 71.3 SS A 7.1 5 340 76 0.06 Calico - Hidalgo 44.9 72.3 SS B 7.1 0.6 5000 95 0.06 Elsinore -Temecula 48.0 77.3 SS B 6.8 5 240 43 0.05 Lenwood-Lockhart-Old Woman Sprgs 49.0 78.9 SS B 7.3 0.6 5000 145 0.06 Elmore Ranch 49.4 79.6 SS B 6.6 1 225 29 1987 5.9 1987 0.04 North Frontal Fault Zone (West) '�q 50.9 82.0 DS B 7.0 1 1314 50 0.06 Elsinore -Coyote Mountain 51.5 82.9 SS B 6.8 4 625 39 0.04 Superstition Mtn. (San Jacinto) 53.5 86.0 SS B 6.6 5 500 24 c. 1440 -- 0.04 Superstition Hills (San Jacinto) 54.3 87.4 SS B 6.6 4 250 23 1987 6.5 1987 0.04 Helendale - S. Lockhardt 56.9 91.6 SS B 7.1 0.6 5000. 97 0.05 San Jacinto -San Bernardino 58.9 94.8 SS B 6.7 12 100 36 6.7 1899 0.03 Elsinore -Glen Ivy 61.6' 99.1 SS B 6.8 5 340 36 6.0 1910 0.04 �3 Notes: 1. Jennings (1994) and CDMG (1996) 2. CDMG & USGS (1996), SS = Strike -Slip, DS = Dip Slip 3. ICBO (1997), where Type A faults: Mmax > 7 and slip rate >5 mm/yr &Type C faults: Mmax <6.5 and slip rate < 2 mm/yr 4. CDMG (1996) based on Wells & Coppersmith (1994), Mw = moment magnitude 5. Modified from Ellsworth Catalog (1990) in USGS Professional Paper 1515 6. 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 (mean plus sigma values are about 1.6 times higher) Based on Site Coordinates: 33.708 N Latitude, I ]6.79 W Longtude and Site Soil Type D EARTH SYSTEMS SOUTHWEST . 1 + - The Centre at La Quinta 08628-01 Table 2 2000 International Building Code (IBC) Seismic Parameters Seismic Category 0.00 D 0.05 Table 1613.3(1) Site Class 1.00 D 1.00 Table 1615.1.1 Latitude: 0.60 33.708 N 0.86 Longitude: 0.75 -116.279 W 1.00 Maximum Considered Earthquake (MCE) Ground Motion Short Period Spectral Reponse Ss 1.50 g Figure1615(3) I second Spectral Response S1 0.60 g Figure1615(4) Site Coefficient Fa 1.00 1.80 Table 1615.1.2(1) Site Coefficient FV 1.50 0.30 Table 1615.1.2(2) 0.27 SMs 1.50 g = Fa*Ss SMI 0.90 g = FV*SI Design Earthquake Ground Motion Short Period Spectral Reponse SDs 1.00 g = 2/3*SMs 1 second Spectral Response SDI 0.60 g = 2/3*SMS To 0.12 sec = 0.2*SDI/SDs Ts 0.60 sec = SDI/SDs 1.2 1.0 rn m U c 0.8 0 a� 0.6 U Q m 0.4 (D CL a) WA • 0.0 1- 0.0 2000 IBC Equivalent Elastic Static Response Spectrum 0.5 1.0 ' 1.5 2.0 Period (sec) EARTH SYSTEMS SOUTHWEST Period Sa T (sec) (g) 0.00 0.40 0.05 0.65 0.12 1.00 0.20 1.00 0.30 1.00 0.60 1.00 0.70. 0.86 0.80 0.75 0.90 0.67 1.00 0.60 1.10 0.55 1.20 0.50 1.30 0.46 1.40 0.43 1.50 0.40 1.60 0.38 1.70 0.35 1.80 0.33 1.90 0.32 2.00 0.30 2.20 0.27 �j karth Systems 11 Southwest 79-811B Country Club Drive, Bemmda Dunes, CA 92201 Boring No: B-1 Drilling Date: April 16, 2002 ProjectName: The Centre at La Quinta SILTY SAND: Light gray -brown; loose; dry; fine to Drilling Method: 8" Hollow Stem Auger File Number: 08628-01 Drill Type: CME 45 with rope and cathead Boring Location: See Boring Location Plan Logged By: Karl A. Harmon v Sample yp Type Penetration 13, 50 for105 5 inches Description of Units Page 1 of 1 i'J Resistance SILTY SAND: Gray -brown; very dense; dry; fine grained, some poorly graded sand and sandy silt Note: The stratification lines shown represent the Q 7 o (Blows/6") ML t~ v o approximate boundary between soil and/or rock types Graphic Trend RF; m q U and the transition may gradational. Dry Density Blow Count U ep...� 5 i j 10 1 1 15 20 E 25 -.A 30 35 •� 40 45 SM SILTY SAND: Light gray -brown; loose; dry; fine to 7, 9, 11 very fine grained, some sandy silt, trace gravel at surface, buried asphaltic concrete (FILL). 13, 50 for105 5 inches SM 2 SILTY SAND: Gray -brown; very dense; dry; fine grained, some poorly graded sand and sandy silt ML SILT: Light olive -brown; medium dense; dry to damp; some sandy silt 7, 9, 13 85 2 ML SANDY SILT: Medium dense; damp; some silty sand 9, 15,22 6, 9, 11 Dry to damp 9, 13, 13 SM SILTY SAND: Light olive -brown; medium dense; dry to damp; fine to very fine grained, some sandy 7, 11, 11 silt TOTAL DEPTH: 31.5 feet No groundwater encountered �j Earth Systems Southwest 79-81 1 B Country Club Drive, Bermuda Dunes, CA 92201 Boring No: B-2 Drilling Date: April 16, 2002 Project Name: The Centre at La Quinta SAND: Gray; very loose; dry; fine grained Drilling Method: 8" Hollow Stem Auger File Number: 08628-01 Drill Type: CME 45 with rope and cathead Boring Location: See Boring Location Plan Logged By: Karl A. Harmon w Sample Type . Penetration ML SILT: Light olive; very loose; dry; partial recovery o B Description of Units Pa e I of 1 v o w, u Resistance _ o N rzZ! 0.0 •o 2 Note: The stratification lines shown represent the Q o (Blows/6") rn ] �� 0 2 c approximate boundary between soil and/or rock types Graphic Trend SILTY SAND: Olive; loose; damp; interbedded �. a., A and the transition may be gradational. Blow Count Dry Density -0 -5 - 10 - 15 - 20 - 25 - 30 - 35 - 40 - 45 SP -SM SAND: Gray; very loose; dry; fine grained l,l,l ML SILT: Light olive; very loose; dry; partial recovery 4, 6, 7 SM/ML 90 4 SILTY SAND: Olive; loose; damp; interbedded silty sand and sandy silt, lenses of poorly graded SP-SM99 5,8,11 4 sand, micaceous SAND: Olive -gray; medium dense; damp; fine to 4, 7, 7 very fine grained, some silty sand. Light olive 4, 5, 7 Olive -gray; loose to medium dense; dry to damp; fine grained, micaceous 8, 22, 26 Dry ML SANDY SILT: Light olive; dry to damp; sandy SM SILTY SAND: Light olive; medium dense; dry to 8, 10, 11 damp; fine to very fine grained, some sandy silt 5,.10, 12 TOTAL DEPTH: 31.5 feet No groundwater encountered r Earth Systems Southwest 79-81113 Country Club Drive, Bermuda Dunes, CA 92201 5 10 15 20 25 30 35 40 45 rtrone 760 345-1588 FAX 760 345-7315 Boring NO: B-3 SM Drilling Date: April 16, 2002 Project Name: The Centre at La Quinta Drilling Method: 8" Hollow Stem Auger File Number: 08628-01 Drill Type: CME 45 with rope and cathead Boring Location: See Boring Location Plan Logged By: Karl A. Harmon Sample 3, 4, 4 v Typeu penetration o � '� o 7.'�.. Description of Units Page 1 of 1 CL t; Resistance 92 2 q F. .3 & Note: The stratification lines shown represent the A S a o (Blows/6") c A _ A a U approximate boundary between soil and/or rock es Graphic Trend p and sandy silt, moist to wet clay layer at approximately 9 Lq and the transition may be y gradational. Blow Count Dry Density 5 10 15 20 25 30 35 40 45 SM SILTY SAND: Light olive -gray; loose; dry; fine to very fine grained, some poorly graded sand, 3, 4, 4 micaceous 4, 6, 10 92 2 Loose to medium dense; damp; some poorly graded sand and sandy silt, moist to wet clay layer at approximately 9 feet SM/ML SILTY SAND: Olive; medium dense; damp to 8, 13,15 83 3 moist; fine to very fine silty sand interbedded with sandy silt, dry to damp silt layer at approximately 14 feet SM SILTY SAND: Light olive -gray; medium dense; dry 7, 9, 12 to damp; fine to very fine, interbedded silt layers 9, 13, 14 a Some sandy silt TOTAL DEPTH: 24 feet No groundwater encountered �j I'Earth Systems Southwest 79-811B County Club Drive, Bermuda Dimes, CA 92201 5 10 15 20 25 30 35 40 45 Phone 760 345-1588 FAX 760 345-7315 BoringNo: B-4 SM Drilling Date: April 16, 2002 Project ame: The Centre at La Quinta Drilling Method: 8" Hollow Stem Auger File Number: 08628-01 a, 4, 5 Drill Type: CME 45 with rope and cathead Boring Location: See Boring Location Plan Logged By: Karl A. Harmon v Sample Type Penetration y 7 v Description of Units Page 1 of 1 W A Resistance o D q .� Note: The stratification lines shown represent the A x pE" o (Blows/6") 100 A Light olive -gray; medium dense; fine grained, some poorly graded sand o approximate boundary between soil and/or rock types Graphic Trend 6, 8, 10 A U and the transition may be gradational. Blow Count Dry Density 5 10 15 20 25 30 35 40 45 SM SILTY SAND: Light olive -brown; loose; dry; fine a, 4, 5 to very fine grained, some sandy silt 7,6,7 7, 11, 13 100 0 Light olive -gray; medium dense; fine grained, some poorly graded sand 6, 8, 10 ML SANDY SILT: Olive brown; medium dense; dry 8'.9,9 Dry to damp TOTAL DEPTH: 21.5 feet No groundwater encountered kj 'Earth Systems tom, southwest 79-811B Country Club Drive, Bermuda Dunes, CA 92201 5 10 15 20 25 30 35 40 45 Phone 760 345-1588 FAX 760 345-7315 Boring No: B-5 SILTY SAND: Light olive; medium dense; dry to damp; fine grained, some poorly graded sand and Drilling Date: April 16, 2002 Project Name: The Centre at La Quinta Drilling Method: 8" Hollow Stem Auger File Number: 08628-01 100 1 Drill Type: CME 45 with rope and cathead Boring Location: See Boring Location Plan Logged By: Karl A. Harmon Sample w Type W Penetration _ ,��� Description of Units Page 1 of I a, v Resistance .n U � A $, _ _ o g Note: The stratification lines shown represent the A 7 a o (Blows/6") A 1 o approximate boundary between soil and/or rock types Graphic Trend A U and the transition may be gradational. Blow Count Dry Density 5 10 15 20 25 30 35 40 45 SM SILTY SAND: Light olive; medium dense; dry to damp; fine grained, some poorly graded sand and 100 1 sandy silt LL Sp -SM SAND: Light olive -gray; medium dense; dry; fine to 4, 7, 9 95 1 very fine grained, some silty sand 9, 14, 15 98 1 ML SANDY SILT: Light olive; medium dense; damp 6, 8, 12 Olive; damp to moist; interbedded sandy and clayey SM SILTY SAND: Olive; medium dense; damp to 5, 7, 7 moist; fine to very fine grained TOTAL DEPTH: 24 feet No groundwater encountered APPENDIX B Laboratory Test Results EARTH SYSTEMS SOUTHWEST i ..J ....3 y APPENDIX B Laboratory Test Results EARTH SYSTEMS SOUTHWEST File No.: 08628-01 April 30, 2002 UNIT DENSITIES AND MOISTURE CONTENT ASTM D2937 & D2216 I Job Name: Centre @ La Quinta 9. Unit Moisture USCS Sample Depth Dry Content Group Location (feet) Density (pcf) (%) Symbol BI 5 105 2 SM BI 10 85 2 ML B2 5 90 4 SM/ML B2 7.5 99 4 SP -SM B3 7.5 92 2 SM B3 12.5 83 3 SM/ML B4 10 100 0 SM B5 2.5 100 1 SM BS 7.5 95 1 SP -SM B5 12.5 98 1 SM/ML .s 17 n DM evc'rrr,re enr rru.xrr0,r 3 r t 'File No.: 08628-01 April 30, 2002 PARTICLE SIZE ANALYSIS ASTM D-422 Job Name: Centre @ La Quints Sample ID: B2 @ 1-4' Feet Description: Sl Silty Sand: F (SP -SM) Sieve Percent Size Passing 1-1/2" 100 1" 100 3/4" 100 1/2" 100 3/8" 100 #4 100 #8 100 #16 100 #30 100 #50 89 #100 39 #200 13 % Gravel: 0 % Sand: 87 % Silt: 11 % Clay (3 micron): 2 (Clay content by short hydrometer method) I IN 11111 111111 11111111 EARTH SYSTEMS SOUTHWEST EARTH SYSTEMS SOUTHWEST File No.: 08628-01 April 30, 2002 PARTICLE SIZE ANALYSIS ASTM D-422 Job Name: Centre @ La Quinta Sample ID: B4 @ 14' Feet Description: Silty Sand: F•(SM) Sieve Percent Size Passing _ 1-1/2" 100 1" 100 3/4" 100 1/2" 100 3/8" 100 #4 100 #8 ` 100 #16 100 % Gravel: 0 ` #30 99 % Sand: 76 #50 92 % Silt: 21 #100 60 % Clay (3 micron): 3 #200 24 (Clay content by short hydrometer method) EARTH SYSTEMS SOUTHWEST ! i File No.: 08628-01 7 April 30, 2002 CONSOLIDATION TEST ASTM D 2435 & D 5333 Centre @ La Quinta B2 @ 5' Feet Silt (SM/ML) Ring Sample 2 1 0 -1 -2 .r -3 x a -4 on Cq - R 5 U -6 ai v L -7 -8 -9 -10 -11 -12 Initial Dry Density: 89.4 pcf Initial Moisture, %: 4.2% Specific Gravity (assumed): 2.67 Initial Void Ratio: 0.864 Hydrocollapse: 0.8% @ 2.0 ksf % Change in Height vs Normal Presssure Diagram O Before Saturation Hydrocollapse ■ After Saturation —IE—Rebound Trend 0.1 1.0 Vertical Effective Stress, ksf 10.0 File No.: 08628-01 April 30, 2002 CONSOLIDATION TEST ASTM D 2435 & D 5333 Centre @ La Quinta B5 @ 12.5' Feet Silt (ML,) Ring Sample 2 1 0 -1 -2 -8 Initial Dry Density: 88.0 pcf Initial Moisture, %: 1.4% Specific Gravity (assumed): 2.67 Initial Void Ratio: 0.895 Hydrocollapse: 1.3% @ 2.0 ksf % Change in Height vs Normal Presssure Diagram O Before Saturation-Hydrocollapse ® After Saturation --W Rebound Trend 1.0 Vertical Effective Stress, ksf F A ATN cvc rP?,AQ CnT T VMXrCCT 10.0 File No.: 08628-01 AP Til 30 2002 MAXIMUM DENSITY / OPTIMUM MOISTURE ASTM D 1557-91 (Modified) Job Name: Centre @ La Quinta Procedure Used: A Sample ID: B2 @ 1-4' Feet Preparation Method: Moist Location: Native Rammer Type: Mechanical Description: Gray Brown: SL Silty Sand: F (SP -SM) Sieve Size % Retained Maximum Density: 103.5 pcf 3/4" 0.0 Optimum Moisture: 12.5% 3/8" 0.0- #4 .0.#4 0.0 130 125 120 115 100 95 90 0 5 10 15 20 25 Moisture Content, percent n .0 File No.: 08628-01 April 30, 2002 MAXIMUM DENSITY / OPTIMUM MOISTURE ASTM D 1557-91 (Modified) Job Name: Centre @ La Quinta Procedure Used: A Sample ID: B4 @ 1-4' Feet Preparation Method: Moist Location: Native Rammer Type: Mechanical Description: Gray Brown: Silty Sand: F (SM) Sieve Size % Retained Maximum Density: 104.5 pcf 3/4" 0.0 Optimum Moisture: 13.5% 3/8" 0.0 #4 0.0 130 125 120 115 110 105 100 95 90 0 5 10 15 20 25 File No-.: 08628-01 April 30, 2002 SOIL CHEMICAL ANALYSES Job Name: Centre @ La Quinta Job No.: 08628-01 Sample ID: B-2 B-4 Sample Depth, feet: 1-4' 1-4' pH: 7.4 8.3 Resistivity (ohm -cm): 390 870 Chloride (Cl), ppm: 267 350 Sulfate (SO4), ppm: 136 28 Note: Tests performed by Subcontract Laboratory: Soil & Plant Laboratory and Consultants, Inc. 79-607 Country Club Drive. Bermuda Dunes, CA 92201 Tel: (760) 772-7995 General Guidelines for Soil Car Chemical A ent 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