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0302-090 (CONR) Geotechnical ReportSUN VISTA DEVELOPMENT CORPORATION " P.O. BOX 1144 LA QUINTA, CALIFORNIA 92253 GEOTECHNICAL ENGINEERING REPORT PROPOSED COMMERCIAL OFFICE BUILDING LOT 7, DESERT CLUB DRIVE AT CALLE AMIGO LA QUINTA, CALIFORNIA December 3, 2002 © 2002 Earth Systems Southwest . Unauthorized use or copying of this document is strictly prohibited without the express written consent of Earth Systems Southwest. 40 41* File No.: 08846-0111 02-12-703 i � 't �1 Earth Systems ti Southwest December 3, 2002 Sun Vista Development Corporation P.O. Box 1144 La Quinta, California 92253 Attention: Mr. Robert Capetz Project: Proposed Commercial Office Building Lot 7, Desert Club Drive at Calle Amigo La Quinta, California ■% Subject: GEOTECHNICAL ENGINEERING REPORT Dear Mr. Capetz: 79-81113 Country Club Drive Bermuda Dunes, CA 92201 (760)345-1588 (800)924-7015 FAX (760) 345-7315 File No.: 08846-01 02-12-703 We take pleasure to present this Geotechnical Engineering Report prepared for the proposed commercial office building to be located on Desert Club Drive at Calle Amigo in the City of La Quinta, California. This report presents our findings and recommendations for site grading and foundation design, incorporating the information provided to our office. The site is suitable for the proposed development provided the recommendations in this report are followed in design and construction. In general, the upper soils should be compacted to improve bearing capacity and reduce settlement. The site is subject to strong ground motion from the San Andreas Fault. 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, authorized on September 12, 2002. Other services that may be required, such as plan review and grading observation, are additional services and will be billed according to our Fee Schedule in effect at the time services are provided. Unless requested in writing, the client is responsible to distribute this report to the appropriate governing agency or other members of the design team. 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,' FESS EARTH SYSTEMS SOUTHWEST woe S otigl cQ' .�O T'9i <<" . cn No. 266 Shelton L. Stringer Exp. 6-30-04 GE 2266 4 c `s�yl 0 CHN�GP��Q SER/sl s/dac F pF C AUEOQ� Distribution: 6/Sun Vista Development Corporation 1/RC File 2/13D File , 1 E�} 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.....................................................................................................5 3.4.1 Seismic Hazards...........................................................................................5 3.4.2 Secondary Hazards.....:.................................................................................6 3.4.3 Site Acceleration and Seismic Coefficients.................................................7 Section 4 CONCLUSIONS....................................................................................................8 Section 5 RECOMMENDATIONS........................................................................................9 SITE DEVELOPMENT AND GRADING........................................................................9 5.1 ' Site Development - Grading....................................................................................9 5.2 Excavations and Utility Trenches..........................................................................10 5.3 Slope Stability of Graded Slopes...........................................................................10 STRUCTURES................................................................................................................11 5.4 Foundations................................................................:...........................................11 5.5 Slabs-on-Grade......................................................................................................12 5.6 Mitigation of Soil Corrosivity on Concrete...........................................................13 5.7 Seismic Design Criteria.........................................................................................13 5.8 Pavements..............................................................................................................14 Section 6 LIMITATIONS AND ADDITIONAL SERVICES..........................................16 6.1 Uniformity of Conditions and Limitations..............................................................16 6.2 Additional Services....................:...........................................................................17 REFERENCES................................:..............................................................................18 APPENDIX A Site Location Map Boring Location Map Table 1 Fault Parameters Logs of Borings APPENDIX B Laboratory Test Results EARTH SYSTEMS SOUTHWEST 11 t it � I A , F) December 3, 2003 Section 1 INTRODUCTION 1of19 GEOTECHNICAL ENGINEERING REPORT PROPOSED CONIlVIERCIAL OFFICE BUILDING LOT 7, DESERT CLUB DRIVE AT CALLE ANHGO LA QUINTA; CALIFORNIA 1.1 Project Description File No.: 08846-01 02-12-703 This Geotechnical Engineering Report has been prepared for the proposed commercial office building to be located on Lot 7, Desert Club Drive at Calle Amigo in the City of La Quinta, California. The proposed office building may be a one or two-story structure. We anticipate that the proposed structure 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, parking lot construction, and concrete driveway and sidewalk placement. Based on existing site topography, site grading is expected to consist of cuts or fills not exceeding 2 feet. We used maximum column loads of 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 structural loading exceeds these assumed values, we would need to reevaluate the given recommendations. 1.2 Site Description The proposed commercial office building is to be constructed on Lot 7 on the northwest corner of Desert Club.Drive and Calle Amigo. The site location is shown on Figure 1 in Appendix A. The project site presently consists of nearly level, vacant lot. The history of past use and development of the property was not investigated as part of our scope of services. No evidence of past development was observed on the site during our reconnaissance. Nonetheless, some previous development of the site is possible. Buried remnants such as old foundations, slabs, or septic systems may exist on the site. There are underground utilities near and within the building area. These utility lines include but are not limited to domestic water, electric, sewer, telephone, cable, and irrigation lines. 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: EARTH SYSTEMS SOUTHWEST December 3, 2002 2 of 19 File No.: 08846-01 02-12-703 ➢ A general reconnaissance of the site. ➢ Shallow subsurface exploration by drilling four exploratory borings to depths ranging from 16.5 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. ➢ Engineering analysis and evaluation of the acquired data from the exploration and testing programs. r➢ A summary of our findings and recommendations in this written report. This report contains the following: ➢ Discussions on subsurface soil and groundwater conditions., ➢ Discussions on regional and local geologic conditions. ➢ Discussions on geologic and seismic hazards. ➢ Graphic and tabulated results of laboratory tests and field studies. ➢ Recommendations regarding: • Site development and grading criteria, • Excavation conditions and buried utility installations, • Structure foundation type and design, • Allowable foundation bearing capacity and expected total and differential settlements, • Concrete slabs -on -grade, • Mitigation of the potential corrosivity of site soils to concrete and steel reinforcement, • Seismic design parameters, • Preliminary pavement structural sections for parking lot. Not Contained In This Report: Although available through Earth Systems Southwest, the current scope of our services does not include: ➢ A corrosive study to determine cathodic protection of concrete or buried pipes. ➢ An environmental assessment. ➢ Investigation for the presence or absence of wetlands, hazardous or toxic materials in the soil, surface water, groundwater, or air on, below, or adjacent to the subject property. EARTH SYSTEMS SOUTHWEST December 3, 2002 3 of 19 File No.: 08846-01 02-12-703 Section 2 METHODS OF INVESTIGATION 2.1 Field Exploration Four exploratory borings were drilled to depths ranging from 16.5 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 September 23, 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-p6und, manually activated by rope and cathead hammer dropping 30 inches in general accordance with ASTM D 1586. Recovered soil samples were sealed in containers and returned to the laboratory. Bulk samples were also obtained from auger cuttings, representing a mixture of soils encountered at the depths noted. The final logs of the borings represent our interpretation of the contents of the field logs and the results of laboratory testing performed on the samples obtained during the subsurface exploration. The final logs are included in Appendix A of this report. The stratification lines represent the approximate boundaries between soil types although the transitions, 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. ➢ 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 December 3, 2002 4 of 19 File No.: 08846-01 02-12-703 Section 3 DISCUSSION 3.1 Soil Conditions The field exploration indicates that site soils consist primarily of medium dense Silty Sand or Sandy Silt that becomes generally very dense at depths greater than 15 feet. The boring logs provided in Appendix A include more detailed descriptions of the soils encountered. The soils are visually classified to be in the very low expansion category in accordance with Table 18A -I -B of the Uniform Building Code. The site lies within a recognized blow sand hazard area. Fine particulate matter (PM10) can create an air quality hazard if dust is blowing. Watering the surface, planting grass or landscaping, or hardscape normally mitigates this hazard. 3.2 Groundwater Free groundwater was not encountered in the borings during exploration. The depth to groundwater in the area is believed ,to be greater than 100 feet based on 1986 water well data obtained from the USGS Water Resources Bulletin 91-4196. Groundwater levels may fluctuate with precipitation, irrigation, drainage, and regional pumping from wells. Groundwater should not be a factor in design or construction at this site. 3.3 Geologic Setting Regional Geology: The site lies within the La Quinta cove area of the Coachella Valley, a part of the Colorado Desert geomorphic province. A significant feature within the Colorado Desert geomorphic province is the Salton Trough. The Salton Trough is a large northwest -trending structural depression that extends from San Gorgonio Pass, approximately 180 miles to the Gulf of California. Much of this depression in the area of the Salton Sea is below sea level: The Coachella Valley forms the northerly part of the Salton Trough. The Coachella Valley contains a thick sequence of sedimentary deposits that are Miocene to recent in age. Mountains surrounding the Coachella Valley include the Little San Bernardino Mountains on the northeast, foothills of the San Bernardino Mountains on the northwest, and the San Jacinto and Santa Rosa Mountains on the southwest. These mountains expose primarily Precambrian metamorphic and Mesozoic granitic rocks. The San Andreas Fault zone within the Coachella Valley consists of the Garnet Hill Fault, the Banning Fault, and the Mission Creek Fault that traverse along the northeast margin of the valley. Local Geology: The project site lies within the La Quinta cove at about 50 feet above mean sea level in the central part of the Coachella Valley. The sediments within the lower part of the cove consist of .fine to coarse-grained sands with interbedded clays, silts of aeolian (wind-blown), lacustrine (lake -bed), and alluvial (water -laid) origin. EARTH SYSTEMS SOUTHWEST December 3, 2002 5 of 19' File No.: 08846-01 02-12-703 3.4 Geologic Hazards Geologic hazards that may affect the region include seismic hazards (ground shaking, surface fault rupture, soil liquefaction, and other secondary earthquake -related hazards), slope instability, ' flooding, ground subsidence, and erosion. A discussion follows on the specific hazards to this site. 3.4.1 Seismic Hazards Seismic Sources: Several active faults or seismic zones lie within 62 miles (100 kilometers) of the project site as shown on Table 1 in Appendix A. The primary seismic hazard to the site is strong groundshaking from earthquakes along the San Andreas and San Jacinto Faults. The Maximum Magnitude Earthquake (M,,,ax) listed is from published geologic information available for each fault (CDMG, 1996). The Mmax corresponds to the maximum earthquake believed to be tectonically possible. Surface Fault Rupture: The project site does not lie within a currently delineated State of California, Alquist-Priolo Earthquake Fault Zone (Hart, 1997). Well -delineated fault lines cross through this region as shown on California 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. Historic Seismicity: Six historic seismic events (5.9 M or greater) have significantly affected the Coachella Valley the last 100 years. They are as follows: • Desert Hot Springs Earthquake - On December 4, 1948, a magnitude 6.5 ML (6.OMw) earthquake occurred east of Desert Hot Springs. This event was strongly felt in the Palm Springs area. • Palm Springs Earthquake - A magnitude 5.9 ML (6.2Mw) earthquake occurred on July 8, 1986 in the Painted Hills causing minor surface creep of the Banning segment of the San Andreas Fault. This event was strongly felt in the Palm Springs area and caused structural damage, as well as injuries. • Joshua Tree Earthquake - On April 22, 1992, a magnitude 6.1 ML (6.1Mw) earthquake occurred in the mountains 9 miles east of Desert Hot Springs. Structural damage and minor injuries occurred in the Palm Springs area as a result of this earthquake. • Landers & Big Bear Earthquakes - Early on June 28, 1992, a magnitude 7.5 Ms (7.3Mw) earthquake occurred near Landers, the largest seismic event in Southern California for 40 years. Surface rupture occurred just south of the town of Yucca Valley and extended some 43 miles toward Barstow. About three hours later, a magnitude 6.6 Ms (6.4Mw) earthquake occurred near Big Bear Lake. No significant structural damage from these earthquakes was reported in the Palm Springs area. • Hector Mine Earthquake - On October 16, 1999, a magnitude 7.1Mw earthquake occurred on the Lavic Lake and Bullion Mountain Faults north of 29 Palms. This event while widely felt; no significant structural damage has been reported in the Coachella Valley. Seismic Risk: While accurate earthquake predictions are not possible, various agencies have conducted statistical risk analyses. In 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 •i EARTH SYSTEMS SOUTHWEST December 3, 2002 6 of 19 File No.: 08846-01 02-12-703 Probabilities (WGCEP, 1995) estimated a 22% conditional probability that a magnitude 7 or greater earthquake may occur between 1994 to 2024 along the Coachella segment of the San Andreas Fault. The primary seismic risk at the site is a potential earthquake along the San Andreas Fault. Geologists believe that the San Andreas Fault has characteristic earthquakes that result from rupture of each fault segment. The estimated characteristic earthquake is magnitude 7.4 for the Southern Segment of the fault. This segment has the longest elapsed time since rupture than any other part•of the San Andreas Fault. The last rupture occurred about 1690 AD, based on dating by the USGS near Indio (WGCEP, 1995). This segment has also ruptured on about 1020, 1300, and 1450 AD, with an average recurrence interval of about 220 years. The San Andreas Fault may rupture in multiple segments producing a higher magnitude earthquake. Recent paleoseismic studies suggest that the San Bernardino Mountain Segment to the north and the Coachella Segment may have both ruptured together in 1450 and 1690 AD (WGCEP, 1995). 3.4.2 Secondary Hazards Secondary seismic hazards related to ground shaking include soil liquefaction, ground subsidence, tsunamis, and seiches. The site is far inland so the hazard from tsunamis is non- existent. At the present time, no water storage reservoirs are located in the immediate vicinity of the site. Therefore, hazards from seiches are considered negligible at this time. Soil Liquefaction: Liquefaction is the loss of soil strength from sudden shock (usually earthquake shaking), causing the soil to become a fluid mass. In general, for the effects of liquefaction to be manifested at the, surface, groundwater levels must be within 50 feet of the ground surface and the soils within the saturated zone must also 'be susceptible to liquefaction. The potential for liquefaction to occur at this site is considered negligible because the depth of groundwater beneath the site exceeds 50 feet. No free groundwater was encountered in our exploratory borings. In addition, the project does not lie within a designated liquefaction hazard zone. Ground Subsidence: The potential for seismically induced ground subsidence is considered to be low at the site. Dry sands tend to settle and densify when subjected to strong earthquake shaking. The amount of subsidence is dependent on relative density of the soil, ground motion, and earthquake duration. Uncompacted fill areas may be susceptible to seismically induced settlement. Based on Tokimatsu and Seed methodology, we estimate that about 1/4 inches of total ground subsidence may occur in the upper 30 feet of soils during the Design Basis Earthquake. 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. EARTH SYSTEMS SOUTHWEST 11 December 3, 2002 7 of 19 3.4.3 Site Acceleration and Seismic Coefficients File No.: 08846-01 02-12-703 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 (EPA) 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. Estimate of PGA and EPA from 1996 CDMG/USGS Probabilistic Seismic Hazard Mans Risk Equivalent Return Period (years) PGA ( ) 1 Approximate EPA ( ) 2 10% exceedance in 50 years 475 T 0.45 1 0.43 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 Engineers 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 seismic and site coefficients given in Chapter 16 of the 1997 Uniform Building Code (UBC) are provided in Section 5.8 of this report. Seismic Hazard Zones: The site does not lie within a liquefaction, landslide or fault rupture hazard area or zone established by the Riverside County and City of La Quinta General Plan. Riverside County has not been mapped by the California Seismic Hazard Mapping Act (Ca. PRC 2690 to 2699).. EARTH SYSTEMS SOUTHWEST 1 i 1 y 1 1 I J1, 1 December 3, 2002 8 of 19 File No.: 08846-01 02-12-703 Section 4 CONCLUSIONS The following is a summary of our conclusions and professional opinions based on the data obtained from a review of selected technical literature and the site evaluation. General: ➢ From a geotechnical perspective, the site is suitable for the proposed development provided the recommendations in this report are followed in the design and construction of this project. Geotechnical Constraints and Mitigation: ➢ The primary geologic hazard is severe ground shaking from earthquakes originating on nearby faults. A major earthquake above magnitude 7 originating on the local segment of the San Andreas Fault zone would be the critical seismic event that may affect the site . within the design life of the proposed development. Engineered design and earthquake - resistant construction increase safety and allow development of seismic areas. ➢ The project site is in seismic Zone 4 and about 12.9 km from a Type A seismic source 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, flooding, and the weight of the intended structures. ➢ The soils are susceptible to wind and water erosion. Preventative measures to reduce seasonal flooding and erosion should be incorporated into site grading plans. Dust control should also be implemented during construction. Site grading should be in strict compliance with the requirements of the South Coast Air Quality Management District (SCAQMD). ➢ Other geologic hazards including fault rupture, liquefaction, seismically induced flooding, and landslides are considered low or negligible on this site. ➢ The upper soils were found to be relatively medium dense silty sands to sandy silts. 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. EARTH SYSTEMS SOUTHWEST December 3, 2002 9 of 19 File No.: 08846-01 02-12-703 Section 5 RECOMMENDATIONS j' SITE DEVELOPMENT AND GRADING 5.1 Site Development - Grading A representative of Earth Systems Southwest (ESSW) should observe site clearing, grading, and the bottom of excavations before placing fill. Local variations in soil conditions may warrant increasing the depth of recompaction and over -excavation. Clearing and Grubbing: At the start of site grading existing vegetation, non -engineered fill, construction debris, trash, and abandoned underground utilities should be removed from the proposed building, structural, and pavement areas. The surface should be stripped of organic growth and removed from the construction area. Areas disturbed during clearing should be properly backfilled and compacted as described below. Dust control should also be implemented during construction. .Site grading should be in strict compliance with the requirements of the South Coast Air Quality Management District (SCAQMD). Building Pad Preparation: 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 3 feet below existing grade or a minimum of 2 feet below 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 D 1557) for an additional depth of 1 -foot. These recommendations are intended to provide a minimum of 4 and 3 feet of moisture conditioned and compacted soil beneath the floor slabs and footings, respectively. Auxiliary Structures Subgrade Preparation: Auxiliary 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 (ASTM D 1557) for a depth of 1 -foot below finished subgrades. Compaction should be verified by testing. Engineered Fill Soils: The native soil is suitable for use as engineered fill and utility trench backfill provided it is free of significant organic or deleterious matter. The native soil should be placed in maximum 8 -inch lifts (loose) and compacted to at least 90% relative compaction (ASTM D 1557) near its optimum moisture content. Compaction should be verified by testing. Rocks larger than 6 inches in greatest dimension should be removed from fill or backfill material. EARTH SYSTEMS SOUTHWEST n December 3, 2002 10 of 19 File No.: 08846-01 02-12-703 Imported fill soils (if needed) should be non -expansive, granular soils meeting the USCS classifications of SM, SP -SM, or SW -SM with a maximum rock size of 3 inches and 5 to 35% passing the No. 200 sieve. The geotechnical engineer should evaluate the import fill soils before hauling to the site. However, because of the potential variations within the borrow source, import soil will not be prequalified by ESSW. The imported fill should be placed in lifts no greater than 8 inches in loose thickness and compacted to at least 90% relative compaction (ASTM D 1557) near optimum moisture content. Shrinkage: The shrinkage factor for earthwork is expected to range from 10 to 20 percent for the upper excavated or scarified site soils. This estimate is based on compactive effort to achieve an average relative compaction of about 92% and may vary with contractor methods. Subsidence is estimated to be about 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 drainage is not provided. Drainage should be maintained for paved areas. Water should not pond on or near paved areas. 5.2 Excavations and Utility Trenches Excavations should be made in accordance with CalOSHA requirements. Our site exploration and knowledge of the general area indicates there is a potential for caving of site excavations (utilities, footings, etc.). Excavations within sandy soil should be kept moist, but not saturated, to reduce the potential of caving or sloughing. Where excavations over 4 feet deep are planned, lateral bracing or appropriate cut slopes of 1:1 (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 Unprotected, permanent graded slopes should not be steeper than 3:1 (horizontal: vertical) to reduce wind and rain erosion. Protected slopes with ground cover may be as steep as 2:1. However, maintenance with motorized equipment may not be possible at this inclination. Fill slopes should be overfilled and trimmed back to competent material. Slope stability calculations are not presented because of the expected minimal slope heights (less than 5 feet). EARTH SYSTEMS SOUTHWEST ! 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. 1 A minimum footing depth of 12 inches below lowest adjacent grade should be maintained. A representative of ESSW should observe foundation excavations before placement of reinforcing steel or concrete. Loose soil or construction. debris should be removed from footing excavations before placement of concrete. Conventional Spread Foundations: Allowable soil bearing pressures are given below "for foundations bearing on recompacted soils as described in Section 5.1. Allowable bearing pressures are net (weight of footing and soil surcharge may be neglected). ➢ Continuous wall foundations, 12 -inch minimum width and 12 inches below grade: 1500 psf for dead plus design live loads Allowable increases of 300 psf per each foot of additional footing width and 300 psf for each additional 0.5 foot of footing depth may be used up to a maximum value of 3000 psf. ➢' Isolated pad foundations, 2 x 2 foot minimum in plan and 18 inches.below grade: 2000 psf for dead plus design live loads Allowable increases of 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 ('/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 'h -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 allowablepassive equivalent fluid EARTH SYSTEMS SOUTHWEST December 3, 2002 11 of 19 File No.: 08846-01 02-12-703 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. 1 A minimum footing depth of 12 inches below lowest adjacent grade should be maintained. A representative of ESSW should observe foundation excavations before placement of reinforcing steel or concrete. Loose soil or construction. debris should be removed from footing excavations before placement of concrete. Conventional Spread Foundations: Allowable soil bearing pressures are given below "for foundations bearing on recompacted soils as described in Section 5.1. Allowable bearing pressures are net (weight of footing and soil surcharge may be neglected). ➢ Continuous wall foundations, 12 -inch minimum width and 12 inches below grade: 1500 psf for dead plus design live loads Allowable increases of 300 psf per each foot of additional footing width and 300 psf for each additional 0.5 foot of footing depth may be used up to a maximum value of 3000 psf. ➢' Isolated pad foundations, 2 x 2 foot minimum in plan and 18 inches.below grade: 2000 psf for dead plus design live loads Allowable increases of 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 ('/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 'h -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 allowablepassive equivalent fluid EARTH SYSTEMS SOUTHWEST 11 December 3, 2002 12 of 19 File No.: 08846-01 02-12-703 pressure of 250 pcf may also be used. These values include a factor of safety of 1.5. Passive resistance and frictional resistance may be used in combination if the friction coefficient is reduced to 0.23 of dead load forces. A one-third (1/3) increase in the passive pressure may be used when calculating resistance to wind or seismic loads. Lateral passive resistance is based on the assumption that backfill next to foundations is properly compacted. 5.5 Slabs -on -Grade 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 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 before 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, 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 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/a 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. EARTH SYSTEMS SOUTHWEST i I' 1 u , December 3, 2002 13 of 19 File No.: 08846-01 02-12-703 Curing and Quality Control: The contractor should take precautions ,to reduce the potential of curling of.slabs in this and desert region using proper batching, placement, and curing methods. Curing is highly effected by temperature, wind, and humidity. Quality control procedures may be ;used including trial batch mix designs, batch plant inspection, and on-site special inspection and testing. Typically, for this type of construction and using 2500 -psi concrete, many of these quality control procedures are not required. 5.6 Mitigation of Soil Corrosivity on Concrete Selected chemical analyses.for corrosivity were conducted on soil samples from the project site as shown in Appendix B. The native soils were found to have low sulfate ion concentration (21 ppm) and moderate chloride ion concentration (411 ppm). Sulfate ions can attack the cementitious material in concrete, causing weakening of the cement matrix and eventual deterioration by raveling. Chloride ions can cause corrosion of reinforcing steel. The Uniform Building Code does not require any special provisions for concrete for these low concentrations as tested. Normal concrete mixes may be used. A minimum concrete cover of three (3) inches should be provided around steel reinforcing or embedded components exposed to native soil or landscape water. Additionally, the concrete should be thoroughly vibrated during placement. Electrical resistivity testing of the soil suggests that the site soils may present a very severe potential for metal loss from electrochemical corrosion processes. Corrosion protection of steel can be achieved by using epoxy corrosion inhibitors, asphalt coatings, cathodic protection, or encapsulating with densely consolidated concrete. Earth Systems does not practice corrosion engineering. We recommend that a qualified corrosion engineer evaluate the corrosion potential on metal construction materials and concrete at the site to provide mitigation of corrosive effects. 5.7 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. EARTH SYSTEMS SOUTHWEST t 1 December 3, 2002 14 of 19 File No.: 08846-01 02-12-703 1997 UBC Seismic Coefficients for Chapter 16 Seismic Provisions 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 The UBC seismic coefficients are based on scientific knowledge, engineering judgment, and compromise. If further information on seismic design is needed, a site-specific probabilistic seismic analysis should be conducted. The intent of the 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 tenets 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. 5.8 Pavements Since no traffic loading were provided by the design engineer or owner, we have assumed traffic loading for comparative evaluation. The design engineer or owner should decide the appropriate traffic conditions for the pavements.. Maintenance of proper drainage is advised to prolong the service life of the pavements. Water should not pond on or near paved areas. The following table provides our preliminary recommendations for pavement sections. Final pavement sections recommendations should be based on design traffic indices and R -value tests conducted during grading after actual subgrade soils are exposed. EARTH SYSTEMS SOUTHWEST Seismic Zone: 4 Seismic Zone Factor, Z: 0.4 . Soil Profile Type: SD Seismic Source Type: A Closest Distance to Known Seismic Source: 12.9 km = 8.0 miles Near Source Factor, Na: 1.00 Near Source Factor, Nv: 1.08 Seismic Coefficient, Ca: 0.44 = 0.44Na Seismic Coefficient, Cv: 0.69 = 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 The UBC seismic coefficients are based on scientific knowledge, engineering judgment, and compromise. If further information on seismic design is needed, a site-specific probabilistic seismic analysis should be conducted. The intent of the 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 tenets 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. 5.8 Pavements Since no traffic loading were provided by the design engineer or owner, we have assumed traffic loading for comparative evaluation. The design engineer or owner should decide the appropriate traffic conditions for the pavements.. Maintenance of proper drainage is advised to prolong the service life of the pavements. Water should not pond on or near paved areas. The following table provides our preliminary recommendations for pavement sections. Final pavement sections recommendations should be based on design traffic indices and R -value tests conducted during grading after actual subgrade soils are exposed. EARTH SYSTEMS SOUTHWEST December 3, 2002 15 of 19 File No.: 08846-01 I1 02-12-703 PRELIMINARY RECOMMENDED PAVEMENTS SECTIONS r 11 1 R -Value SubQrade Soils 40 (assumed) Design Method — CALTRANS 1995 Notes: 1. Asphaltic concrete should be Caltrans, Type B, '/i -in. or 3/a -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/a in. maximum) and compacted to a minimum of 95% of ASTM D1557 maximum dry density near its optimum moisture. 3. All pavements should be placed on 12 inches of moisture -conditioned subgrade, compacted to a minimum of 90% of ASTM D 1557 maximum dry density near its optimum moisture. 4. Portland cement concrete should have a minimum of 3250 psi compressive strength @ 28 days. 5. Equivalent Standard Specifications for Public Works Construction (Greenbook) may be used instead of Caltrans specifications for asphaltic concrete and aggregate base. EARTH SYSTEMS SOUTHWEST Flexible Pavements Rigid Pavements Asphaltic Aggregate Portland Aggregate Traffic Concrete Base Cement Base Index Pavement Use Thickness Thickness Concrete Thickness (Assumed) (Inches) (Inches) (Inches) (Inches) 4.0 Auto Parking Areas 2.5 4.0 4.0 4.0 Notes: 1. Asphaltic concrete should be Caltrans, Type B, '/i -in. or 3/a -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/a 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 n December 3, 2002 16 of 19 File No.: 08846-01 1 02-12-703 Section 6 LIMITATIONS AND ADDITIONAL SERVICES 6.1 Uniformity of Conditions and Limitations Our findings and recommendations in this report are based on selected points of field exploration, laboratory testing, and our understanding of the proposed project. Furthermore, our findings and recommendations are based on the assumption that soil conditions do not vary significantly from those found at specific exploratory locations. Variations in soil or groundwater conditions could exist between and beyond the* exploration points. The nature and extent of these variations may not become evident until construction. Variations in soil or groundwater may require additional studies, consultation, and possible revisions to our recommendations. Findings of this report are valid as of the issued date of the report. However, changes in conditions of a property can occur with passage of time whether they are from natural processes or works of man on this or adjoining properties. In addition, changes in applicable standards occur whether they result from legislation or broadening of knowledge. Accordingly, findings of this report may be invalidated wholly or partially by changes outside our control. Therefore, this report is subject to review and should not be relied upon after a period of one year. In the event that any changes in the nature, design, or location of structures are planned, the conclusions and recommendations contained in this report shall not be considered valid unless the changes are reviewed and conclusions of this report are modified or verified in writing. This report is issued with the understanding that the owner, or the owner's representative, has the responsibility to bring the information and recommendations contained herein to the attention of the architect and engineers for the project so that they are incorporated into the plans and specifications for the project. The owner, or the owner's representative, also has the responsibility to verify that the general contractor and all subcontractors follow such recommendations. It is further understood that the owner or the owner's representative is responsible for submittal of this report to the appropriate governing agencies. As the Geotechnical Engineer of Record for this project, Earth Systems Southwest (ESSW) has striven to provide our services in accordance with generally accepted geotechnical engineering practices in this locality at this time. No warranty or guarantee is express or implied. This report was prepared for the exclusive use of the Client and the Client's authorized agents. ESSW should be provided the opportunity for a general review of final design and specifications in order that earthwork and foundation recommendations may be properly interpreted and implemented in the design and specifications. If ESSW is not accorded the privilege of making this recommended review, we can assume no responsibility for misinterpretation of our recommendations. Although available through ESSW, the. current scope of our services does not include an environmental assessment, or investigation for the presence or absence of wetlands, hazardous or EARTH SYSTEMS SOUTHWEST IJ December 3, 2002 17 of 19 File No.: 08846-01 02-12-703 toxic materials in the soil, surface water, groundwater or air on, below, or adjacent to the subject . property. 6.2 Additional Services This report is based on the assumption that an adequate program of client consultation, construction monitoring, and testing will be performed during the final design and construction ' phases to check compliance with these recommendations. Maintaining ESSW as the geotechnical consultant from beginning to end of the project will provide continuity of services. The geotechnical engineering firm providing tests and observations shall assume the responsibility of Geotechnical Engineer of Record. Construction monitoring and testing would be additional services provided by our firm. The costs of these services are not included in our present fee arrangements, but can be obtained from our office. The recommended review, tests, and observations include, but are not necessarily limited to the following: • Consultation during the final design stages of the project. • Review of the building and 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 needed during construction. -000- Appendices as cited are attached and complete this report. 4- � I EARTH SYSTEMS SOUTHWEST December 3, 2002 18 of 19 File No.: 08846-01 02-12-703 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. 1 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. 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. 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, 1769-1989" 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., 1997, Fault -Rupture Hazard Zones in California: California Division of Mines and Geology Special Publication 42. International Conference of Building Officials, 1997, Uniform Building Code, 1997 Edition. International Conference of Building Officials, 2000, International Building Code, 2000 Edition. Jennings, CW, 1994, Fault Activity Map of California and Adjacent Areas: California Division of Mines and Geology, Geological Data Map No. 6, scale 1:750,000. Petersen, M.D., Bryant, W.A., Cramer, C.H., Cao, T., Reichle, M.S., Frankel, A.D., Leinkaemper, J.J., McCrory, P.A., and Schwarz, D.P., 1996, Probabilistic Seismic Hazard Assessment for the State of California: California Division of Mines and Geology Open -File Report 96-08. Reichard, E.G. and Mead, J.K., 1991, Evaluation of a Groundwater Flow and Transport Model of the Upper Coachella Valley, California, U.S.G.S. Open -File Report 91-4142. Riverside County Planning Department, 1984, Seismic Safety Element of the Riverside County General Plan. Rogers, T.H., 1966, Geologic Map of California - Santa Ana Sheet, California Division of Mines and Geology Regional Map Series, scale 1:250,000. EARTH SYSTEMS SOUTHWEST December 3, 2002 19 of 19 File No.: 08846-01 02-12-703 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. 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 J .APPENDIX A Site Location Map Boring Location Map Table 1 Fault Parameters Logs of Borings EARTH SYSTEMS SOUTHWEST �I z 0 M"Iffi-IL" NAN\, AW 'AU ro 0 cq. ...... i---------------- 0 --A t p G o -10 er 50 Water g; It if U U J I Ii We 410 0 0 C,2 6 & ----- - Mv La�a�. E;$L:wh �raUc�t :sss ,�,z _ ��br _� • OD r-..QacLJ ���o��.� xexx. oma..: v V. -�k, q 1 -1 S EF-1 - P,' W- -�,D L��c-�o���. _ :oar"0 ..._ �t:_.... �_HQ ____, _9� P� 1,a in 1�!i e�. w��i�� Reference: USGS Topographic Map, La Quinta Quadrangle, 1980 (photor, Scale: 1" = 2,000' OMMMM?MMMNM� 0 2,000. 4,000 Figure 1 - Site Location Lot 7 Desert Club Drive File No.: 08826-01 nEarth Systems =10P Southwest LEGEND Figure 2 - Boring Locations Approximate Boring Location Lot 7 Desert Club Drive File No.: 08826-01 Scale: 1" = 30' 30' 60' Earth Systems Southwest Lot 7 Desert Club Drive Table 1 Fault Parameters & & Deterministic Estimates of Mean Peak Ground Acceleration (PGA) 08846-01 Fault Name or Seismic Zone Distance from Site (mi) (lurn) 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 8.0 12.9 SS A 7.4 24 220 203 c. 1690 0.35 San Andreas - Mission Crk. Branch 8.4 13.4 SS A 7.1 25 220 95 6.5 1948 0.30 San Andreas - Banning Branch 8.4 13.5 SS A 7.1 10 220 98 6.2 1986 0.30 San Jacinto (Hot Spgs - Buck Ridge) 14.5 23.4 SS C 6.5 2 354 70 6.3 1937 0.13 Blue Cut 16.5 26.6 SS C 6.8 1 760 30 -- 0.14 San Jacinto-Anza 18.9 30.4 SS A 7.2 12 250 91 5.5 1928 0.16 Burnt Mtn. 19.3 31.0 SS B 6.4 0.6 5000 20 1992 6.1 1992 0.10 San Jacinto -Coyote Creek 19.3 31.0 SS B 6.8 4 175 41 1968 6.5 1968 0.12 Eureka Peak ,�, 20.4 32.8 SS B 6.4 0.6 5000 19 1992 6.1 1992 0.09 Morongo 30.0 48.3 SS C 6.5 0.6 1170 23 5.5 1947 0.06 Pinto Mountain 31.7 51.0 SS B 7.0 2.5 499 73 0.08 San Jacinto - Borrego 33.3 53.5 SS B 6.6 4 175 29 6.5 1942 0.06 Emerson So. - Copper Mtn. 34.1 54.9 SS B 6.9 0.6 5000 54 0.07 Landers 34.5 55.4 SS B 7.3 0.6 5000 83 1992 7.3 1992 0.09 San Jacinto -San Jacinto Valley 35.6 57.4 SS B 6.9 12 83 43 6.8 1918 0.07 Pisgah -Bullion Mtn. -Mesquite Lk 36.3 58.4 SS B 7.1 0.6 5000 88 1999 7.1 1999 0.08 Earthquake Valley 37.6 60.5 SS B 6.5 2 351 20 0.05 North Frontal Fault Zone (East) 40.3 64.8 DS B 6.7 0.5 1727 27 0.06 Brawley Seismic Zone 41.0 66.0 SS B 6.4 25 24 42 5.9 1981 0.04 Elsinore -Julian 41.6 67.0 SS A 7.1 5 340 76 0.07 Johnson Valley (Northem) 45.3 72.8 SS B 6.7 0.6 5000 36 1992 7.3 1992 0.05 Elsinore -Temecula 45.8 73.7 SS B 6.8 5 240 43 0.05 Calico - Hidalgo 47.3 76.2 SS B 7.1 0.6 5000 95 0.06 Elmore Ranch 48.9 78.8 SS B 6.6 1 225 29 1987 5.9 1987 0.04 Elsinore -Coyote Mountain 49.0 78.9 SS B 6.8 4 625 39 0.05 Lenwood-Lockhart-Old Woman Sprgs 50.7 81.6 SS B 7.3 0.6 5000• 145 0.06 Superstition Mtn. (San Jacinto) 51.8 83.4 SS B 6.6 5 500 24 c. 1440 -- 0.04 North Frontal Fault Zone (West) 52.0 83.7 DS B 7.0 1 1314 50 0.06 Superstition Hills (San Jacinto) 52.9 85.1 SS B 6.6 4 250 23 1987 6.5 1987 0.04 Helendale - S. Lockhardt 58.1 93.5 SS B 7.1 0.6 5000 97 0.05 San Jacinto -San Bernardino 58.7 94.4 SS B 6.7 12 100 36 6.7 1899 0.03 Elsinore -Glen Ivy 60.2 96.8 SS B 6.8 5 340 36 6.0 1910 0.04 motes: 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: 33.673 N Latitude, 116.302 W Longtude and Site Soil Type D EARTH SYSTEMS SOUTHWEST ' *'Earth Systems So thwest 79-81113 Country Club Drive, Bermuda Dunes, CA 92201 ' SM SILTY SAND: light olive gray, medium dense, dry, fine to very fine grained, some sandy silt, silt lenses 5 11,8,10 94 1 i 10 11,19,24 95 1 dry to damp ' I 15 16,32,47 ML 97 3 SILT: light olive, very dense, dry to damp - 20 16,50/4" dry _ I 25 9,27,40 dense, some very fine silty sand 30 15,50/4" damp Boring completed at 31.5 feet 35 Backfilled with cuttings No groundwater encountered ' 40 Earth Systems Southwest79-81111Country Club Drive, Bermuda Dunes, CA 92201 ' SM SILTY SAND: light olive, medium dense, dry, fine to very fine grained, some sandy silt ' 9,14,22 87 3 5 i 10 11,22,29 101 1 dense, lenses of sand and silty sand ML SANDY SILT: ver light olive, densedr g Y , Y 15 16,36,50 97 ] 23,50/4" dry to damp 20 1 Boring completed at 20 feet Backfilled with cuttings No groundwater encountered 25 30 35 ' 40 Earth Systems t� Southwest 79-811B Country Club Drive, Bermuda Dunes, CA 92201 Phone (760) 345-1588, Fax (760) 345-7315 Boring No: B^3 Drilling Date: September 23, 2002 ProjectName: Lot 7, Desert Club Drive @ Calle Amigo, La Quinta, CA Drilling Method: 8" HSA File Number: 08846-01 Drill Type: CME 45 w/rope and cathead Boring Location: See Figure 2 Logged By: Karl Harmon Sample Type Penetration v Description of Units Page 1 of I Resistance 0 ' CO a-62= U q Note: The stratification lines shown represent the x q T ] o approximate boundary between soil and/or rock types Graphic Trend q 0 (Blows/6") U)q U and the transition may be gradational. Blow Count Dry Density SM SILTY SAND: light olive, medium dense, dry to T. damp, fine to very fine grained, some sandy silt 6,8,8, dry 5 ML SANDY SILT: light olive, medium dense, dry to damp, some silt lenses 11,13,14 10 10,14,20 dense, dry to damp 15 SM SILTY SAND: light olive, dense, dry, fine grained to fine grained, silt lenses, silt at tip ML SILT: light olive, dense, dry 13,17,22 20 Boring completed at 20.5 feet Backfilled with cuttings No groundwater encountered 25 30 35 Art 1.0Earth Systems Southwest 79-811B Country Club Drive, Bermuda Dunes, CA 92201 ML SANDY SILT: light olive, stiff, dry 8,11,19 SM 90 2 SILTY SAND: light olive dense dr, fine to ver 5 12,22,30 99 2 g Y, Y fine some sandy silt grained, ML SANDY SILT: light olive, medium dense, dry, some silty sand 10 9,9,9 ' 15 10,18,20 dense ' Boring completed at 16.5 feet Backfilled with cuttings ' 20 No groundwater encountered 25 i 30 35 40 APPENDIX B Laboratory Test Results EARTH SYSTEMS SOUTHWEST File No.: 08846-01 October 14, 2002 UNIT DENSITIES AND MOISTURE CONTENT ASTM D2937 & D2216 Job Name: Lot 7, Desert Club B1 5 Unit Moisture USCS Sample Depth Dry Content Group Location (feet) Density (pcf) (%) Symbol B1 5 94 1 SM B 1 10 95 1 SM B 1 15 97 3 ML B2 3.5 87 3 SM B2 8.5 101 1 SM B2 13.5 97 1 ML B4 2 90 2 ML B4 5 99 2 SM EARTH SYSTEMS SOUTHWEST Filo No.: 08846-01 October 14, 2002 PARTICLE SIZE ANALYSIS ASTM D-422 Job Name: Lot 7, Desert Club Sample ID: B3 @ 1-3' Feet Description: Silty Sand: F w/ Gravel (SM) Sieve Percent Size Passing 1-1/2" 100 1" 100 3/4" 100 1/2" 99 3/8" 99 #4 99 #8 99 #16 98 % Gravel: 1 #30 98 % Sand: 67 #50 93 % Silt: 23 #100 62 % Clay (3 micron): 9 #200 32 (Clay content by short hydrometer method) 1■ 1 �■1 11� 11 �■ ILI 11111111E 1111 I! e�� eINN EARTH SYSTEMS SOUTHWEST Rile. No.: 08846-01 October 14, 2002 MAXIMUM DENSITY / OPTIMUM MOISTURE ASTM D 1557-91 (Modified) Job Name: Lot 7, Desert Club Procedure Used: A Sample ID: B3 @ 1-3' Feet Preparation Method: Moist Location: Native Rammer Type: Mechanical Description: Brown: Silty Sand, F (SM) Sieve Size % Retained Maximum Density: 113 pcf 3/4" 0.0 Optimum Moisture: 12.5% 3/8" 0.9 #4 1.4 140 135 130 125 110 105 100 0 5 10 15 20 25 Moisture Content, percent EARTH SYSTEMS SOUTHWEST File No.: 08846-01 SOIL CHEMICAL ANALYSES Job Name: Lot 7, Desert Club Job No.: 08846-01 Sample ID: B-3 Sample Depth, feet: 1-4' pH: 8.5 Resistivity (ohm -cm): 435 Chloride (Cl), ppm: 411 Sulfate (SOA ppm: 21 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 Corrosivitv October 14, 2002 Chemical Agent Amount in Soil Degree of Corrosivity Soluble 0 -1000 ppm Low Sulfates 1000 - 2000 ppm Moderate 2000 - 5000 ppm Severe > 5000 ppm Very Severe Resistivity 1-1000 ohm -cm Very Severe 1000-2000 ohm -cm Severe 2000-10,000 ohm -cm Moderate 10,000+ ohm -cm Low EARTH SYSTEMS SOUTHWEST