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06-3450 (CONR) Geotechnical Engineering Report" RJT HOMES, LLC P. O. BOX 810 LA QUINTA, CALIFORNIA 92253 ov ®� saVE�Y OEC BOLE 11�1G FOR 001,1 U DATE 1-- GEOTECHNICAL ENGINEERING REPORT r PROPOSED RESIDENTIAL DEVELOPMENT SEC OF,AVENUE 52- AND JEFFERSON STREET LA QUINTA, CALIFOIA October 30, 2003 © 2003 Earth Systems Southwest Unauthorized use or copying of this document is strictly prohibited without the express written consent of Earth Systems Southwest. File No.: 09386-01 03-10-847 r Earth Systems 1� Southwest 79-311B Country Club Drive Barmuda Dunes, CA 92201 (760)345-1588 (800)924-7015 FAX (760) 345-7315 October 30, 2003 File No.: 09386-01 03-10-847 RJT Homes, LLC P. O. Box 810 La Quinta, California 92253 Attention:. Mr. Chad Myer Project: Proposed Residential Development SEC of Avenue 52 and Jefferson Street La Quinta, California Subiect: GEOTECHNICAL ENGINEERING REPORT Dear Mr. Myer: We take pleasure in presenting this Geotechnical Engineering Report prepared for the proposed residential development to be located at the southeast corner of Avenue 52 and Jefferson Street 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, dated September 25, 2003. Other services that may be required, such as plan review and grading observation, are additional services and will be billed according to our Fee •Schedule in effect at the time services are provided. Unless requested in writing, the client is responsible for distributing this report to the apppopriate 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 Reviewed by, Karl A. Harmon EG 2243• SER/kah/csh/nrm Distribution: 6/RJT Homes, LLC 1/RC File 2/BD File Craig S. Hill CE 38234 I TABLE OF CONTENTS EXECUTIVE SUMMARY.... Page ..................... ii Section 1 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 2.1 Field Exploration ................................ 2.2 Laboratory Testing .............................. 2.3 Infiltration Testing .............................. Section3 DISCUSSION.........................................................................................................6 3.1 Soil Conditions........................................................................................................6 DEVELOPMENT AND GRADING......................................................................12 3.2 Groundwater............................................................................................................6 Site Development - Grading..................................................................................12 3.3 Geologic Setting......................................................................................................6 Excavations and Utility Trenches..........................................................................13 3.4 Geologic Hazards.....................................................................................................7 Slope Stability of Graded Slopes...........................................................................13 3.4.1 Seismic Hazards...........................................................................................7 5.4 3.4.2 Secondary Hazards......................................................................................8 5.5 3.4.3 Site Acceleration and Seismic Coefficients .................................................9 Section4 CONCLUSIONS..................................................................................................11 Section 5 RECOMMENDATIONS.....................................................................................12 SITE DEVELOPMENT AND GRADING......................................................................12 5.1 Site Development - Grading..................................................................................12 5.2 Excavations and Utility Trenches..........................................................................13 5.3 Slope Stability of Graded Slopes...........................................................................13 STRUCTURES........................................................................................................:........14 5.4 Foundations............................................................................................................14 5.5 Slabs-on-Grade......................................................................................................15 5.6 Retaining Walls.....:................................................................................................16 5.7 Mitigation of Soil Corrosivity on Concrete...........................................................16 5.8 Seismic Design Criteria..................................:......................................................17 5.9 Pavements..........:............................................................................................:......18 Section 6 LIMITATIONS AND ADDITIONAL SERVICES..........................................20 6.1 Uniformity of Conditions and Limitations............................................................20 6.2 Additional Services................................................................................................21 REFERENCES...............................................................................................................22 APPENDIX A Site Location Map. Boring Location Map Table 1 Fault Parameters Logs of Borings APPENDIX B Laboratory Test Results EARTH SYSTEMS SOUTHWEST 11 EXECUTIVE SUMMARY The site is located at the southeast corner of Avenue 52 and Jefferson Street in the City of La Quinta, California. Preliminary development plans include 109 single-family homes and 36 duplex units. We understand that the proposed structures will be one and two-story, wood -frame and stucco construction supported with perimeter wall foundations and concrete ;slabs -on -grade. The proposed project may be constructed as planned, provided that the recomn-endations in this report are incorporated in the final design and construction. Site developn-ent will include demolition of existing structures and removal of undocumented fill, clearing and grubbing of vegetation, site grading, building pad preparation, underground utility instalLation, street and parking lot construction, and concrete driveway and sidewalks. Based of the noz-uniform nature and the hydro -collapse potential of the near surface soils, remedial site grading is recommended to provide uniform support for the foundations. We consider the most significant geologic hazard to the -project to be the potential for moderate to severe seismic shaking that is likely to occur during the design life of the proposed structures. The project site is located in the highly seismic Southern California region within the influence' of several fault systems that are considered to be active or potentially active. Tne site is located in Seismic Zone 4 of the 2001' California Building Code (CBC). Structures should be designed in accordance with the values and parameters given within the CBC. The seismic design parameters are presented in the following table and within the report. EARTH SYSTEMS SOUTHWEST .. = SUMMARY OF RECOMMENDATIONS Design Item Recommended Parameter Reference Section No. Foundations Allowable Bearing Pressure 5.4 Continuous wall footings n 1,500 psf�/. fi Pad Column footings 1,800. ` sf'✓ Foundation Type ' - r; Spread Footing t 5.4' Bearing Materials' Engineered fill Allowable Passive Pressure 300 psf per foot * 5.4 ' Active Pressure35 pcf 5.6 At -rest Pressure 55 pcf 5.6 Allowable Coefficient of Friction 0.35 5.4 Soil Expansion Potential .-Ver low EI<20 • -3.1 Geologic Hazards & Seismic Liquefaction Potential Low 3.5.2 Significant Fault and Magnitude San Andreas, M7.7 5.8 Fault Type s A, 5.8 Seismic Zone 4 r 5.8 Soil Profile Type Sp 5.8 Near -Source Distance 6.7 km 5.8 �• Seismic Coefficient, NA 1.00 `5.8 r Seismic Coefficient, Nv 1.17 5.8 Pavement TI equal to, 4.5 (Light Traffic) " 2.5" AC / 4.0" AB 5.9 ` TI equal to 7.0 (Heavy Traffic) 4.0"'AC / 8.0" AB 5.9 ; Slabs Building Floor Slabs On eri ineered fill 5.5 Modulus of Sub rade Reaction •200 pci ' 5.5 ' 'Existing Site Conditions -Existing Fill N/A Soil Corrosivity ' Low sulfates low chlorides 5.7 Groundwater Depth• Presently >60 feet, Historic <50 feet 3.2 - Estimated Fill and Cut includes over -excavation <5 feet -fill >10 feet -*.cut 1:1 `. ,The recommeridations contained within this report are' subject to the limitations presented in • Section 6 of this report. We recommend that all individuals'using this report read,the limitations. ' • ..w. Ar .• �, i ••. ' � '. - i.. - ,-, a r, . l E .e• � i -.'EARTH SYSTEMS SOUTHWEST October 30, 2003 1 of 22 File No.: 09386-01 03-10-847 GEOTECHNICAL ENGINEERING REPORT PROPOSED RESIDENTIAL DEVELOPMENT SEC OF AVENUE 52 AND JEFFERSON STREET LA QUINTA, CALIFORNIA Section 1 INTRODUCTION 1.1 Project Description This Geotechnical Engineering Report has been prepared for the proposed residential development to be located at the southeast corner of Avenue 52 and Jefferson Street in the City of La Quinta, California. The proposed single and multi -family dwellings will include one and two-story structure. We understand 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, residential street construction, and concrete driveway and sidewalk placement. Based on existing site topography and ground conditions, site grading is assumed to consist of fills not exceeding 5 feet and cuts of about 15 feet. We used maximum column loads of 20 kips and a maximum wall loading of 1 S 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, wr would need to reevaluate the given recommendations. 1.2 Site Description The approximately 15 -acre project site is an irregular shaped parcel located south of Avenue 52 and east of Jefferson Street in the City of La Quinta,.California. The. site loca-ion and vicinity are shown on Figure 1 in Appendix A. Currently, the majority of the site consists of vacant land with a relatively sparse growth of native brush and weeds. An existing residential structure that is. currently being used as a bank is located in the northeast corner of the site. A large elevated pad (10-1.5 ft. above native grade) is located in the west -central portion of the site, as well as an east -west strip of imported fill soil (5- 1.0 ft. above native grade) placed near the central portion of the site. Several large trees: are located on and around the elevated pad. Aside from the elevated pad and strip of imported fill, the site is relatively flat and level with adjacent properties. Scattered trash and debris was observed throughout the site. Drainage of the site is accomplished through infiltration and sheet flow. Site elevation is approximately 30 feet above sea level. The project site is bounded to the north by Avenue 52, to the west by Jefferson Street, to the east by vacant land and to the south by the All American Canal (Coachella Canal). EARTH SYSTEMS SOUTHWEST October 30,'2003- '2 of 22 File No.: 09386-01 03-10-847 The history of past use and development of the property was not investigated as part of our scope of services. The USGS La Quinta Quadrangle Map indicates a structure located_ in the western portion of the site. Evidence of some past development was observed in the .vicinity of the elevated pad on the site during our reconnaissance. Buried remnants such as old foundations, slabs, or septic systems are likely to 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:. R. 1.3 Purpose and Scope of Work The purpose for our services was to evaluate the site soil conditions and to provide professional opinions and recommendations regarding the proposed development of the site. The scope of work included the following: ➢ . A general reconnaissance of the site. ➢ Shallow subsurface exploration by drilling seven exploratory borings to depths ranging from 14 to 50 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 other sites in the vicinity. ➢ Engineering analysis and evaluation of the acquired data from the exploration and testing programs. ➢ A summary of our findings and recommendations in this written report." This report contains the following: ➢ Discussions on subsurface soil and groundwater conditions. ➢ Discussions on regional and local geologic conditions.' ➢ Discussions on geologic and seismic hazards. ➢ Graphic and tabulated results of laboratory tests and field studies: ➢ Recommendations regarding: { • Site development and grading criteria, • Excavation conditions and buried utility installations, - • Structure foundation type and design, • Allowable foundation bearing capacity and expected total and differential settlements,, _ Concrete slabs -on -grade, • Lateral earth pressures and coefficients, • Mitigation .of the potential corrosivity of site soils to concrete and steel reinforcement,, - • Seismic design parameters; Preliminary pavement structural sections. Not Contained'In This Report: Although available through Earth Systems Southwest, the current scope of our services does not include: ➢ A corrosive study to determine cathodic protection of concrete or buried pipes. ➢ An environmental assessment. EARTH SYSTEMS SOUTHWEST r. October 30, 2003 4 of 22 File No.:.09386-01 03-10-847 Section 2 METHODS OF INVESTIGATION 2.1 Field Exploration . Seven exploratory borings were drilled to depths ranging from 14 to 50 feet below the existing ground surface to observe the soil profile and to obtain .samples for laboratory testing. The borings were drilled on October 3, 2003. 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 approximat-, 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 insice diameter. The samples were obtained by driving the sampler with a 140 -pound, hammer manually activated by rope and cathead dropping 30 inches in general accordance with ASTM D 1586L Recovered soil samples were sealed in containers and returned to the laboratory. Bulk sa_�nples• 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 s.ratification 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 (ASTtM.D 2937). ➢ Maximum density tests .were performed to evaluate the moisture -density relationship of typical soils encountered (ASTM D 1557). ➢ 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. October 30, 2003 5 of 22 File No.: 09386-01 03-10-847 ➢ 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. 2.3 Infiltration Testing An infiltration test was performed within the vicinity of one of the proposed retention basins as shown on Figure 2. The test was conducted within an 8 -inch diameter augered borehole made to a depth of about 10 feet below existing ground surface. A 3 -inch diameter perforated pipe was set in the borehole and backfilled with'gravel around the pipe. Water was injected at a relatively constant rate until a stabilized head of water was established. Based on th.- US Bureau of Reclamation methodology for a constant head, pump -in test, the follcwing hydraulic_, conductivity rates were obtained. Test ID Bottom of Hole feet Water Head feet Flow Rate m Hydraulic Conductivity. in/hr al/sf/da B_4 10 5 1 1.5 22 The designer of the retention basin should decide on an appropriate factor of safety to apply to the reported infiltration rate. Infiltration may be significantly less than the values given over time because of siltation of the well bottom and development of a film- from roac oils from paved streets. A. silt and oil trap placed at influent points may be considered to reduce the potential for reduction in the infiltration rate of soils: EARTH SYSTEMS SOUTHWEST I October 30, 2003 Section 3 DISCUSSION 3.1 Soil Conditions 6 of 22 File No.: 09386-01 03-10-847 The field exploration indicates that site soils consist generally of medium dense interbedded fine grained sand and silty sand (SP -SM and SM) with occasional silt layers (ML).. 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 (EI < 20) category in,accordance with Table 18A -I -B of the California 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 0.5 to 2.2 % 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 (PM�o) 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 60 feet, based on water well data obtained from the USGS Water Resources Bulletin 91-4196. However, there is uncertainty in the accuracy of short-term water level measurements. Groundwater levels may fluctuate with precipitation, irrigation, drainage, regional pumping from wells, and site grading.' The absence of groundwater levels detected may not represent an accurate or permanent condition. Groundwater should not be a factor in design or construction at this site. 3.3 Geologic Setting Regional Geology: , The site lies within the Coachella Valley, a part of the Colorado Desert geomorphic province. A significant feature within the Colorado Desert geomorphic province is the Salton Trough. The Salton Trough is a large northwest -trending structural depression that extends from San Gorgonio Pass, approximately 180 miles to the Gulf of California. Much of this depression in the area of the Salton Sea is below sea level. The Coachella Valley forms the northerly part of the Salton Trough. The Coachella Valley contains a thick sequence of sedimentary deposits that are Miocene to recent in age. Mountains surrounding the Coachella Valley include the Little San Bernardino Mountains on the northeast, 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. . -EARTH SYSTEMS SOUTHWEST A S October 30, 2003 .7 of 22 File No.: 09386-01 03-10-847 Local Geology: The project site is located in the southern portion of the Coachella Valley near the eastern flanks of the Santa Rosa Mountains at an elevation of approximately 30 feet above mean sea level. The project is located in an area that was once covered by .he ancient Lake Cahuilla. The sediments in this area of the valley generally consist of fine-grained sands with interbedded clays and silts of aeolian (wind-blown), lacustrine (lake bed), ane alluvial (water - laid) origin. 3.4 Geologic Hazards Geologic hazards that may affect the region include seismic hazards (ground shaking, surface fault rupture, soil liquefaction, and other secondary, earthquake -related hazards), slope instability, flooding, ground subsidence, and erosion. A discussion follows on the specific hazards to this site. 3.4.1 Seismic Hazards Seismic Sources: Several active faults or seismic zones lie within 62 miles (100 kilometers)- of the project site as shown on Table 1 in Appendix A. The primary seismic hazard to the site. is strong groundshaking from earthquakes along the San Andreas and San Jacinto Faults. The Maximum Magnitude Earthquake (MmaX) listed is from published geologic information available for each fault (Cao et. al, CGS, 2003). The Mmax corresponds to the maximum earthquake believed to be tectonically possible. Surface Fault Rupture: The project site does not lie within a currently delineated State of California, Alquist-Priolo Earthquake Fault Zone (Hart, 1997). Well -delineated fault lines cross through this region as shown on California Geological Survey (CGS) maps (Jennings, 1994).. Therefore, active fault rupture is unlikely.to occur at the project site. While fault rupture would most likely occur along previously established fault traces, future fault rupture could occur at other locations. Historic Seismicity: Six historic seismic events (5:9 M orgreater) 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 truly 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 andcaused 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 irjuries 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 year.. 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 whil-. widely felt, no significant structural damage has been reported in the Coachella Valley. EARTH SYSTEMS SOUTHWEST October 30, 2003 .8 of 22 File No.: 09386-01 03-10-847 Seismic Risk: While accurate earthquake predictions are not possible, variolas agencies have conducted statistical risk analyses. In 2002, the California Geological Survey (CGS) and the United States Geological Survey (USGS). completed the latest generation of pro-Dabilistic seismic hazard maps. We have used these maps in our evaluation of -the seismic risk at the site. The Working Group of California Earthquake Probabilities (WGCEP, 1995) estimated a 22% conditional probability that a magnitude 7 or greater earthquake may occur between 1994 to 2024 along the Coachella segment of the San Andreas Fault. The primary seismic risk at the site is a potential earthquake along the San Andreas Fault. Geologists believe that the San Andreas Fault has characteristic earthquakes that result from rupture of each fault segment. The estimated characteristic earthquake is magnitude 7.7 for the Southern Segment of the fault (USGS, 2002). 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 fXGCEP, 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 massa In general, fir 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 becF-use the depth of groundwater beneath the site exceeds 50 feet. No free groundwater was encountered in our exploratory borings. In addition, the project does not lie within the Riverside County H State designated liquefaction hazard zone. Ground Subsidence: The potential for seismically induced ground subsidence is considered to be moderate at the site. Dry sands tend to settle and densify when subjected to strong earthquake shaking. The amount of subsidence is dependent on relative density of the soil.. ground motion, and earthquake duration. Uncompacted fill areas may be susceptible to seismically induced settlement. Slope Instability: The site is relatively flat. Therefore, potential hazards from. slope instability,` landslides, or debris flows are considered negligible. Flooding: The project site does not lie within a designated FEMA 100 -year flood plain. The project site may be in an area where sheet flooding and erosion could occur-. If significant EARTH SYSTEMS SOUTHWEST October 30, 2003 9-of,22 _ y File No.:.09386-01 . 03710-847 changes are proposed for the site, appropriate project design,. construction, and maintenance can minimize the site sheet flooding potential. 3.4.3 Site Acceleration and Seismic Coefficients Site Acceleration: The potential intensity of ground motion may be estimated ':)y 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. 'Grcund motions are dependent primarily on the earthquake magnitudeand distance to the seisrrpogenic (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 consideu ably in the same general area. This variability can be expressed statistically by a standard deviat_on about a mean relationship. The PGA alone is an inconsistent scaling factor to compare to the CBC Z factor and is generally a poor indicator of potential structural damage, during an earthquake. _ Important factors influencing.the structural performance are the duration and frequency of strong ground motion, " local subsurface conditions, soil -structure interaction, and structural details. Because of these factors, an effective peak acceleration (EPA) is used in structural design. The following table provides the probabilistic estimate of the PGA and EP?_ taken from the 2002 CGS/USGS seismic hazard maps. r EARTH SYSTEMS SOUTHWEST October 30,` 2003 10.of 22 File No.: 09386-01. 03-10-847 - ` Estimate of PGA and EPA from 2002 CGS/USGS Probabilistic Seismic. Hazard Maps i P quivalent Return Approximate - Risk Period ears PGA ' EPA 2 .. IAn/ ______ 1_ ___ _ LA ___.__ 1. - I A - I A Notes: 1. Based on a soft rock site,`SBic and soil amplification factor of 1.0 for Soil Profile Type Sp. • 2. Spectral acceleration (SA) at period of 0.2 seconds divided by 2.5 for 5% damping, as defined by the International Building Code. 2001 CBC Seismic Coefficients: The California .Building Code (CBC) seismic design criteria . are based on a Design Basis Earthquake (DBE) that has an earthquake ground motion with a 10% probability of occurrence in 50 years. The PGA and EPA estimates given. above are provided for information on the seismic risk inherent in the CBC design. The seismic and site coefficients given in Chapter 16 of:the 2001 California Building Code are provided below. 2001 CBC Seismic Coefficients for Chapter 16 Seismic Provisions , R Reference Seismic Zone. 4 Figure 16-2. Seismic Zone Factor, Z: 0:4 Table 16-I Soil Profile Type: Sp Table 16-J Seismic Source Type: A Table '16-U Closest Distance to Known Seismic Source: 10.8 km = 6.7 miles (San Andreas Fault) Near Source Factor, Na: 1:00' Table 16-S Near Source Factor, Nv: 1.17Table 16-T ' Seismic Coefficient, Ca: 0.44 • = 0.44Na Table 16-Q = ' Seismic Coefficient, CV: 0.75 = 0.64Nv Table 16-R, 'Seismic Hazard Zones: The site.does not lie within a liquefaction, landslide or fault rupture hazard area or zone established by the 2002 Riverside County General Plan. Riverside County has not been mapped by the California Seismic Hazard Mapping Act (Ca. PRC 2690 to 2699).. EARTH SYSTEMS SOUTHWEST October 30, 2003 11 of 22 File No.: 09386-01 03-10-847 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. "t 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, is of soil profile Type Sq and is about 10.8 km from a Type A seismic source as defined in the California Building Code. A qualified professional should design any permanent structure constructed on the site. , The minimum seismic design should comply with the 2001 edition of the California Building Code. ➢ Adherence to the grading and structural recommendations"in this report should reduce potential settlement problems from seismic forces, heavy rainfall or irrigation, flooding, and the weight of the intended structures. , ➢ The soils are susceptible to wind and water erosion. Preventative measures to reduce seasonal flooding and erosion should' be incorporated into site grading plans. Dust control should also be implemented during construction. Site grading should be in strict' compliance with the requirements of the South. Coast Air Quality Management District (SCAQMD). ➢' Other geologic hazards including fault rupture, liquefaction, seismically induced flooding, and landslides are considered low or negligible on this site. ➢ The upper soils were found to.be relatively loose to medium dense and ire 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. , "' EARTH SYSTEMS SOUTHWEST October 30, 2003 12. of 22 File No.: 09386-01 03-10-847 Section 5 ' RECOMMENDATIONS SITE DEVELOPMENT AND GRADING 5.1 Site Development -,Grading A representative of Earth Systems Southwest (ESSW) should observe site clearing, grading, and the bottom of excavations before placing fill. Local variations in soil conditions may warrant increasing the depth of recompaction and over -excavation. Clearing and Grubbing: At the start of site grading, existing vegetation, tnees, large roots, pavements, foundations, non -engineered fill, construction debris, trash, and abandoned underground utilities should be removed from the proposed building, structural, and pavement areas. The surface should be stripped of organic growth and removed from the construction area. Areas disturbed during demolition and clearing should be properly backfilled and compacted as described below. • Dust control should also be implemented during construction. Site grading should be in strict compliance with the requirements of the South Coast Air Quality Management District (SCAQMD). Building Pad Preparation: Because of the relatively non-uniform and under -compacted nature 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) in addition to the removal of the stockpiles of soils. The over -excavation would 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% re]L.ive compaction (ASTM D 1557) for an additional depth of 1 -foot. Deep excavations will be n:cessary in cases where pools/spas penetrate the depth of compaction. In these cases, the pool/spa should be compacted to at least 2 feet below the bottom of the pool/spa. 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 su.:)grade should be scarified, moisture conditioned, and compacted to at least 90% rela-ive ' 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 End utility trench backfill, provided it is free of significant organic or deleterious matter. The native soil should be placed in maximum 8 -inch lifts (loose) and compacted to at least 90% relative compaction (ASTM.D 1557) near its optimum moisture content. Compaction should be verified by testing. EARTH SYSTEMS SOUTHWEST October 30,.2003 13 of 22 File No.: 09386-01 03-10-847 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 (ASTMD 1557) near optimum moisture content. Shrinkage: The shrinkage factor for earthwork is expected to. range from 5 to 15 percent for the upper excavated or scarified site soils. This estimate is based on compactive effort to achieve an average relative compaction of about 92%.and may vary with contractor methods. Subsidence is estimated to range from 0.1 to 0.2 feet. Losses from site clearing and removal of existing site improvements may affect earthwork quantity calculations and should be considered. Site Drainage: Positive drainage should be maintained away from the structures (5% for 5 feet minimum) to prevent ponding and subsequent saturation of the foundation soils. Gutters and downspouts should be considered as a means to convey water away from foundations if adequate drainage is not provided. Drainage should be maintained for paved. areas. Water should not pond on or near paved areas. 5.2 Excavations and Utility Trenches Excavations should be made in accordance with CalOSHA requirements. Our site exploration and knowledge of the general area indicates there is a potential for caving of site excavations (utilities, footings, etc.). Excavations within sandy soil .should be kept moist, but not saturated, to reduce the .potential of caving or sloughing. Where excavations over 4 feet deep are planned, lateral bracing or appropriate cut slopes of 1.5:1 (horizontal: vertical) should be provided. No surcharge loads from stockpiled soils or construction materials should be allowed within a horizontal distance measured from the top of the excavation slope, equal to the depth of the excavation. Utility Trenches: Backfill of utilities within road or public right-of-ways should be placed in conformance withAhe 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 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). Octbber 30, 2003 14 of 22 - He No.: 09386-01 03-10-847 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 r --commended 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 1.2 inches below lowest adjacent grade should be maintained. A representative of ESSW should observe foundation excavations before placeme-'it 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. A1_owable 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 2 500 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 2300 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 ar_d the grading requirements. ` Minimum reinforcement for continuous wall footings should be two, No. 4 steel _einforcing 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 engi-ieer. Expected Settlement: Estimated total static settlement should be less than 1 inch, based on footings founded on firm soils as recommended. Differential settlement between exterior and interior bearing members should be less than. %2 -inch, expressed in a post -construction angular distortion ratio of 1:480 or less. Frictional and Lateral Coefficients: Lateral loads may be resisted by soil friction, on the. base of. foundations and by passive resistance of the soils acting on foundation walls. An allowable coefficient of friction of 0.35 of dead load may be used. An allowable passive equivalent fluid pressure of 250 pcf may also be used. These, values include a factor of safety'of L5. Passive EARTH SYSTEMS SOUTHWEST October 30, 2003 15 of 22 File No.: 09386-01 03-10-847 resistance and frictional resistance may be ,used in combination if the friction coefficient is reduced by one-third. A .one-third ('/3) increase in the passive pressure may be used when calculating resistance to wind or seismic loads. Lateral passive resistance. is based on the assumption that backfill next to foundations is properly compacted. 5.5 -Slabs-on-Grade Sub rg ade: Concrete slabs -on -grade and flatwork should be supported by compacted soil placed in accordance with Section 5.1 of this report. Vapor Retarder: In areas of moisture sensitive floor coverings, an appropriate vapor retarder should be installed to reduce moisture transmission from the subgrade soil to the slab. For these areas an impermeable membrane (10 -mil thickness) should underlie the floor slabs. The membrane should be covered with -2 inches of sand to help protect it during construction and. to 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 membrane is dependent upon its quality, method of overlapping, its protection during construction,. and the successful sealing 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 ('/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 arid desert region using proper batching, placement, and curing'methods. Curing is highly effected by temperature, wind, and humidity. Quality control procedures may EARTH SYSTEMS SOUTHWEST October 30, 2003 16 of 22 File No.: 09386-01 03-10-847 be used including trial batch mix designs, batch plant inspection, and on-site soecial 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 deign. The values are given as equivalent fluid pressures, without surcharge loads or hydrostatic pressure. Lateral Pressures and Sliding Resistance' Granular Back -fill Passive Pressure 375 pcf - 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 Z Acting at 0.5H, 18H psf or 50 pef 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 stabiliy 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 ac:ive earth pressure. Walls retaining less than 6 feet of soil and not supporting inhabitable structures need not consider this increased pressure (reference: CBC Section 1630A. 1. 1.5). Upward sloping backfill or surcharge loads from nearby footings can create larger lateral pressures. Should any walls be considered for retaining sloped backfill or- placed next to foundations, our office should be contacted for recommended design parameters. Surcharge loads should be considered if they exist within a zone between the face of the wall and a plane projected 45 degrees upward from the base of the wall. The increase in lateral earth pressure should be taken as 35% of the surcharge load within this zone. Retaining walls subjected to traffic loads should include a'uniform surcharge load equivalent to at least 2 feet :)f 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 whyn the specific application is determined. Backfill immediately behind the retaining structure should be a free - draining granular material. Waterproofing should be according to the designer's specifications. Water should not be 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. Foundtation subgrade preparation should be as specified in Section 5.1 5.7 Mitigation of Soil Corrosivity on Concrete EARTH SYSTEMS SOUTHWEST , October 30, 2003 17 of 22 FileNo.:409386-01 • - 03-10-847 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 (70 . and 80 ppm) and low chloride ion concentration (88 and 1.4,7 ppm). Sulfate ions can attack the cementitious material in concrete, causing, weakening of the cement matrix, and eventual deterioration by raveling. Chloride ions can cause corrosion of reinforcing steel. The California Building Code 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. 5.8 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 2001 edition of the California Building Code using the. seismic coefficients given in the table below. n 'EARTH SYSTEMS SOUTHWEST ' ' October 30, 2003 18 of 22 Fire No.: 09386-01 03-10-847 2001 CBC Seismic Coefficients for Chapter 16 Seismic Provisions Reference . Seismic Zone: 4 Figure 16-2 Seismic Zone Factor, Z: 0.41. Table 16-1 Soil Profile Type: So Table 16-J Seismic Source Type: A Table. 16-U Closest Distance to Known Seismic'Source: 10.8 km = 6.7 miles (San Andreas Fault) Near Source Factor, Na: 1.00 Table. 16-S. . Near Source Factor, Nv: 1.17 Table 16-T Seismic Coefficient, Ca: 0.44 = 0.44Na Table 16-Q Seismic Coefficient, Cv: 0.75 = 0.64Nv Table16-R The CBC seismic coefficients are based on scientific knowledge, engineering judgment, and compromise. If .further information on seismic design is -needed, a site-spec_fic probabilistic seismic analysis should be conducted. The intent of,the CBC lateral force requirements is to provide a structural design that will resist collapse to provide reasonable life safety from a major earthquake, but may experience some structural and nonstructural damage. A fundamental tenet of seismic design is that inelastic yielding is allowed to adapt to the seismic demand on the structure. In other words,, damage is allowed. The CBC lateral force requirements should be considered a minimAtm design. "The owner and the designer should evaluate the level of risk and performance thEit is acceptable. Performance, based, criteria could be set in the design. The design engineer should exercise special care so that all components of the design are 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 was 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 October 30, 2003 19 of 22 Fide No.: 09386-01 t - 03 -10 -847 - PRELIMINARY RECOMMENDED PAVEMENTS SECTIONS R -Value Subgrade Soils - 50 (assumed) Design Method — CALTRANS 1995 Notes: 1. Asphaltic concrete should be Caltrans, Type 13, ''/2 -in. or'/4-in. maximum -medium grading and compacted to a minimum of 95% of the 75 -blow Marshall density (ASTM D 1559) or equivalent. < 2._ Aggregate base should be Caltrans Class 2.(3/4 in. maximum) and compacted to a minimum of 95% of ASTM D1557 maximum dry density near its optimum moisture. 3. All pavements should be placed on 12 inches of moisture -conditioned subgrade.'compacted to•a . minimum of 90%'of ASTM D 1557 maximum dry densitynear 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. r EARTH SYSTEMS SOUTHWEST Flexible Pavements Ri id Pavements Asphaltic Aggregate Portland Aggregate , Traffic, Concrete Base Cement Base lndex - Pavement Use Thickness Thickness Concrete Thickness Assumed Inches Inches) (Inches)' Inches 4.5 Auto Parking Areas 2.5" 4.0 4.0 4.0 5.0 Residential Streets 3:0 4.0 5.0 4.0 Notes: 1. Asphaltic concrete should be Caltrans, Type 13, ''/2 -in. or'/4-in. maximum -medium grading and compacted to a minimum of 95% of the 75 -blow Marshall density (ASTM D 1559) or equivalent. < 2._ Aggregate base should be Caltrans Class 2.(3/4 in. maximum) and compacted to a minimum of 95% of ASTM D1557 maximum dry density near its optimum moisture. 3. All pavements should be placed on 12 inches of moisture -conditioned subgrade.'compacted to•a . minimum of 90%'of ASTM D 1557 maximum dry densitynear 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. r EARTH SYSTEMS SOUTHWEST October 30, 2003 20 of 22 File No.: 09386-01 03-10-847 k 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 app_icable 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 inn 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 -epresentative 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 authorize] 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 October 30, 2003 21 of 22 - File No.: 09386-01 03-10-847 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 :)f engineered' fill as required by CBC.Sections 1701 and 3317 .or local grading ordinances: • Consultation as needed during construction. _000 - Appendices as cited are attached and complete this report. EARTH SYSTEMS SOUTHWEST October 30, 2003 22 of 22 File No.: 09386-01 03-10-847 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. Blake, T.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. California Geologic Survey (CGS), 199.7, Guidelines for Evaluating. and Mitigating Seismic Hazards in California, Special Publication 117. Cao, T, Bryant, W.A., Rowhandel, B., Branum. -D., and Wills, C., 2003, The Revised 2002 California . Probabilistic Seismic Hazard Maps, California Geologic Survey (CGS), June 2003. California Department of Water Resources, 1964, Coachella Valley Investigation, Bulletin No. 108, 146 pp. Envicom Corporation and the County of Riverside Planning Department, 1976, Seismic Safety and Safety General Plan Elements Technical Report, County of Riverside. Frankel, A.D., et. al, 2002, Documentation, for the 2002 Update of the National Seismic Hazard Maps, USGS Open -File Report 02-420. Hart, E.W., 1997, Fault -Rupture Hazard Zones in California: California Division of Mines and ' Geology Special Publication 42. M International Code Council (ICC), 2002, California Building Code, 2001 Edition. International Code Council (ICC), 2003, International Building Code, 2003 Edition Jennings, C.W, 1994, Fault Activity Map of California and Adjacent Areas: California Division of Mines and Geology, Geological Data Map No. 6, scale 1:750,000. Petersen, M.D., Bryant, W.A., Cramer, C.H., Cao, T., Reichle, M.S., Frankel, A.D., Leinkaemper, J.J., McCrory, P.A., and Schwarz, D.P., 1996, Probabilistic. Seismic Hazard Assessment for the State of California: California Division of Mines and Geology Open -File Report 96-08. Proctor, R. J., 1968, Geology of the Desert Hot Springs - Upper Coacheila 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, 2002, Geotechnical Element of the Riverside County General Plan — Hearing Draft. EARTH SYSTEMS SOUTHWEST' October 30, 2003 123 of 22 File No.: 09386-01 03-10-847 Rogers, T.H., 1966, Geologic Map of California - Santa Ana Sheet, California Division of Mines and Geology Regional Map Series, scale* 1:250,000. 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. r EARTH SYSTEMS SOUTHWEST I\99NO11V:I1 : 1 >.•wf.. ... °Q /i °itit p 1. .ra •� .i .•.. d•• ,14 - AVENU�1 .5 i� C. _ 19 •l`. a.,� :.��:::,.,•.,n-<..� -.- _ 111.;4: •..:::'A; •:::..:: �:.. a• II' :. ..fi••:' / I :� � on••. JJ ,•�'•. Ilii. •. e.•• r1 ..: ( ....•.•.:°. p °. .°..•. r.. �'•1 •Ills•••••.•°I►. ........• •..•.•...r••. 1.Y•••••a•r•4. 1/ •I •.C1•.•• •••••n••..11 ••.. fir. :•:. •.1 •yl'••a'Ir •�.i • �. •.• mC��P ,, .•••.•..•• •...• 1. >•.....•` 11•.:M•.....a r• a• •. ••.•°r • mm¢• .pr�)'.m J1=w.• °••• •e...P it • •.. ••.. ••rr•°S•••e.•• e••• r Y� •!•••.. 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Puln it is 11 r n 111 I 0It r' .,\\.'•.) t . 1 = Ir r .1 II 0it U 0 it It AV NUS II I '•� . ! n • __ _ � � y N V % /• __ _ _ _9�a J —.. 15 „tis__ EenII L&4fitIt )is•�, it �~ Y�•I i II ° it /— �\ .•. I?n II• .... :••II •• II 11 �'�• n it II{{ e I� •.r 0-: " II " n 1 .•11 •:• cum Base Map: U.S.GS. 7.5 Minute Quadrangles, La Quinta, CA (1980) Figure 1 Site Location Map .......... Approximate Site Boundary SEC Avenue 52 and Jefferson Street La Quinta, California Scale: 1" = 2,000' N � Earth Systems out west 0 2,000' 4,000' I 10/30/03 1 09386-01 KT Ilk, y w 4M1'•.,y�.iV�J�4if'IJ,�Yi.JN r � . r w 4 ■ i lr�+ �. r fy ¢ 1 ! ■� Ir OW, �' , LEGEND Figure 2 Boring Location Map Approximate Boring Locations SEC Avenue 52 and Jefferson Street La Quinta, California Earth Systems I outhwest Not to Scale — 10/30/03 .09386-01 SEC Avenue 52 and Jefferson Street 09386-01 Table 1 Fault Parameters& & Deterministic Fstiotates of Mean Peak Ground Acceleration WC.AI Fault Name or Seismic Zone Distance • from Site (m i) (km) Fault Type Maximum Magnitude Mmax (Mw) Avg Slip Rate (mm/yr) Avg Return Period (yrs) Fault Length (km) Mean Site PGA (g) Reference Notes: (1) (2) (3) (4) (2) (2) (2) (5) San Andreas - Southern y 6.7 10.8 SS A . 7.7 24 220 199 0.42 San Andreas -.Mission Crk. Branch 7.9 12.8 SS., A 7.2 25 220 95 0.31 San Andreas - Banning Branch 7.9 12.8 SS A 7.2 10 220 98 0.31 San Jacinto (Hot Spgs - Buck Ridge) 15.6 25.1 SS C 6.5 2 354 70 0.13 Blue Cut 16.5 26.5 SS C 6.8 1 760 30 0.14 San Jacinto-Anza 19.8 31.9 SS' A 7.2 '12 250 91 0.15 Burnt Mtn. 20.0 32.1 SS B 6.5 0.6 5000 21 0.10 San Jacinto -Coyote Creek 20.6 33.2 SS B 6.8 4 175 41 -0.11 Eureka Peak 20.9 33.6 SS B 6.4 0.6 5000 19 0.09 Morongo 31.2 50.3 SS C 6.5 0.6 1170 23 0.06 San Jacinto - Borrego 32.8 52.7 SS B 6.6 4 175 29 0:06 Pinto Mountain 32.8 52.8 SS B 7.2 2.5 499 74 0.09 Emerson So. - Copper Mtn. 33.9 54.6 SS B 7.0. 0.6 5000 54 0.08 Landers 35.1 56.4 SS B 7.3 0.6 5000 83 0.09 Pisgah -Bullion Mtn. -Mesquite Lk 35.5 57.2 SS B 7.3 0.6 5000 89 0.09 San Jacinto -San Jacinto Valley 37.7 .60.6 SS B 6.9 12 83 43 , 0.07 Earthquake Valley 38.3. 61.7 SS B 6.5 2 351 20 0.05 Brawley Seismic Zone 39.2 63.1 SS B 6.4 25 24 42 • 0.05 North Frontal Fault Zone (East) 41.2 66.3 DS B 6.7 0.5 1727 27 0.06 Elsinore -Julian 42.7 68.8 SS A 7.1 5 340 76 0.07 Johnson Valley (Northern) 45.8 73.8 SS B 6.7 0.6 5000 35 0.05 Elmore Ranch 47.2 76.0 SS B 6.6 1 225 29 0.04 Calico - Hidalgo '47.4 76.4 SS B 1.3 0.6 5000 95 0.07 Elsinore -Temecula 47.5 76.5 SS B 6.8 5 240 43 0.05 Elsinore -Coyote Mountain 49.0 78.9 SS B 6.8 4 625 39 0.05 Superstition Mtn. (San Jacinto) 50.8 81.8 SS B 6.6 5 500 24 0.04 Lenwood-Lockhart-Old Woman Sprgs 51.7 83.1 SS B 7.5 0.6 .5000 145 0.07 Superstition Hills (San Jacinto) 51.7 _ 83.2 SS B 6.6 4 250 23 0.04 North Frontal Fault Zone (West) 52.1 83.9 DS B 7.2 1 1314 50 0.07 Helendale -.S. Lockhardt 59.4 95.6 SS B 7.3 0.6 5000 97 0.05 San Jacinto -San Bernardino Y 60.6 97.5' SS B 6.7 12 100 36 . 0.04 Notes: 1. Jennings (1994) and California Geologic Survey (CGS) (2003) 2. CGS (2003), SS = Strike -Slip, DS = Dip Slip, BT = Blind Thrust 3. 2001• CBC, where Type A faults: Mmax > 7 & slip rate >5 mm/yr & Type C faults: Mmax <6.5 & slip rate, < 2 mm/yr 4. CGS (2003) 5. The estimates of the mean Site PGA are based on the following attenuation relationships: Average of: (1) 1997 Boore, Joyner & Fumal; (2) 1997 Sadigh et al; (3) 1997 Campbell , (4) 1997, Abrahamson ,& Silva (mean plus sigma values are about 1.5 to 1.6 times higher) Based on Site Coordinates: 33.671 N Latitude, 116.266 W Longtude and Site Soil Type D EARTH SYSTEMS SOUTHWEST Y Earth Systems a . ` VFW Southwest 79-81 IB Country Dub Drive, Bermuda Dunes, CA 92201 -5 - 10 15. 20 = 25 = 30 - 35 -40 - 45 50 - 55 rnone tiov��y�-n�aa rr�n do"�w�-ron Boring No: B-1 SP -Slut Drilling Date: October 3, 2003 , Project Name: SEC Avenue 52 & Jefferson Street, La Quinta, CA Drilling Method: 8" hollow stcm auger File Number: 09386-01 . 8,13,16 Drill Type: CME 45 w/rope & cathead Boring Location: See Figure 2 dense, dry, fine grained gravelly artificial fill at surface Logged By: Karl Harmon Sample Type Penetration 7,9,13 °?' Description of Units Page 1 of 1 v . Resistance _ ° U "' O c •F' 2 Note: The stratification lines shown re resent the P Y p 108 1 CV,, a C` ° c approximate boundary between soil and/or rock types Graphic Trend p m a. 0 (Blows/6") C] U and the transition may be gradational. Blow Count Dry Density' -5 - 10 15. 20 = 25 = 30 - 35 -40 - 45 50 - 55 SP -Slut SAND WITH SILT: light olive gray, medium. . 8,13,16 dense, dry, fine grained gravelly artificial fill at surface ` 7,9,13 98 . 11,16,24 108 1 damp, fine to medium grained ML SILT: dusky yellow, medium dense, moist 5,8,10 85 33 , SM SILTY SAND: light olive gray,.medium dense, a,5,7 damp to moist, very fine to fine grained, interbedded with sand with silt, lenses of silt ' Total Depth 21.5 feet . No groundwater encountered 0 Earth Systems Southwest 79-811 B County �Iub Drive, Bennuda Dunes, CA 92201 Phone (760) 3454588 FAX(760)345-7315 Boring No: B-2 Drilling Date: October 3, 2003 Project Name: SEC Avenue 52 & Jefferson Street, La Quinta, CA Drilling Method: 8" hollow stem auger File Number: 09386-01, Drill Type: .CME 45 w/rope & cathead .Boring Location: See Figure 2 Logged By: Karl,Harmon Sample Type Penetration 2 Description of Units Page 1 of 1 ul Resistance _ E U V) � °' cz- n a, K r- = Note: The stratification lines shown re resent the p Y o i — c approximate boundary between soil and/or rock types Graphic Trend Q" m 0 (Blows/6") U) O � j and the transition may be gradational. Blow Count Dry Density SM SILTY. SAND: light olive gray,.medium dense, dry_ to damp, very 'fine to fine grained 7,13,15 95 3 gravelly artificial fill w/asphalt chunks on surface 5 , 9,16,20 95 3 damp, some sand with silt 10 ' 6 6 7 damp to moist, silt lens at tip 15. • SM/ML SILTY SAND TO SANDY SILT: light olive gray, �I 8,7,6 medium dense, moist to wet, interbedded 20 Total Depth 19 feet No groundwater encountered • 25 30 35 k . • 40 45 50 55 k s k Earth Systems �� Southwest 79-811 B Country _'lub Drive, Bermuda Dunes, CA 92201 - 35 - 40 - 45 ' 11 SM SILTY SAND: light olive gray, medium dense, dry to damp, very fine to fine grained, some sand -with ' 7'12'14 silt, shells SP -Slut N. SAND WITH SILT: light olive gray, medium' 11,14,21 96 l dense, dry, very fine to fine grained, some silt; sand . 12,16,23.' 97 4 damp 7,5,6 fine to medium grained SM/ML SILTY SAND TO SANDY SILT: light olive gray, medium dense, moist, very fine to fine grainec, silty ' SP -SM sand interbedded with moist silt and sandy silt 6,7,7 ' SAND WITH SILT: medium olive brown, medium dense, damp to moist, very fine to fine grained, - interbedded with silty sand, some silt lenses 9,12,18 light olive gray,, medium dense to dense, damp, fire grained 8,12,19 medium olive brown, dense, fine to medium grained ML SILT: medium olive brown, moist to wet, clay -,y SP -Slut SAND WITH SILT: light olive gray, medium dense, damp, fine grained, silt lens at tip 10,13,13 16,20,24 dense Total Depth 50 feet No groundwater encountered Earth Sys Southwest 79-811 B Country Dub Drive, Bermuda Dunes, CA 92201 Phone (760) 345-1588 FAX (760) 345-7315 Boring No: B-4 Drilling Date: October 3, 2003 Project Name: SEC Avenue 52 & Jefferson Street, La Quinta, CA Drilling Method: 8" hollow stem auger, File Number: 09386-01 Drill Type: CME 45 w/rope & cathead Boring Location: See Figure 2 Logged By: Karl Harmon Sample Type Penetration Y Description of Units Page 1 of 1 tL Y _ U Resistance �° U � °' o Q Q, � Note: The stratification lines shown represent the . p o E ] , 2 c approximate boundary between soil and/or rock types Graphic Trend Q m a. (Blows/6") p t j and the,transition may be gradational. Blow Count Dry Density SM SILTY SAND: light olive gray, medium dense, dry to damp, very fine to fine grained, some sand with 9,19,21 96 1 silt 5 7,10,13 90 q. 10 SP -SM SAND WITH SILT: light olive gray, medium • 4,6,6 dense, damp, fine grained 15 Total Depth 14 feet , No groundwater encountered 10' perforated pipe set in adjacent hole for testing 20 25. 30 71 35 40 45 f. 50 , ' 5'5 ; 7 A 7 Earth Syst, +Southwest 79-811 B Country Club Drive, Bermuda Dunes, CA 92201 rnone t ioul sa3- roes rnx t ioul s4.) -is u .Boring No:"B-5 i Drilling Date: October 3, 2003 Project Name: SEC Avenue 52 & Jefferson Street, La Quinta, CA Drilling Method: 8" hollow stem auger File Number: 09386-01 Drill Type.' CME 45 w/rope & cathead Boring Location: See Figure 2 Logged By: Karl Harmon Sample Type Penetration _ 2 Description of,UnitS Page 1 of 1 ° Resistance. U aU °' n C Note: The stratification lines shown represent the � Q . •" ° Y p E ° c approximate boundary between soil and/or rock types Graphic Trend p m • un (Blows/6") p V and the transition may be gradational. Blow Count Dry Density - 20 - 25 - 30 - 35 -40 45 w - SM 50 55 w - SM SILTY SAND: light olive gray; medium dense, dry d fine grained; some sand with silt ' 7 9 11 85 6,7,10 88 l SP -SM SAND WITH SILT: light olive gray, medium - dense, damp, fine grained 6,10,14 92 3 • 7,6,5 fine to medium grained ML" SILT: grayish olive, medium dense, wet; interbedded, sandy and clayey SM SILTY SAND: grayish olive, medium dense, hoist 314'7 to wet; very fine to fine grained, with interbed•jed silt layers Total Depth 21.5 feet 1. No groundwater encountered w - Earth ' Systems Southwest 79-811 B Country Zlub Drive, Bermuda Dunes, CA 92201 Phone (760) 345-»588 FAX(760)345-7315 Boring No:.B-6 Drilling Date: October 3, 2003 Project Name: SEC Avenue 52 & Jefferson Street, La Quinta, CA Drilling Method: 8" hollow stem auger ,File Number:' 09386-01 Drill Type: CME 45 w/rope & cathead Boring Location: See Figure 2 Logged By: Karl Harmon .v . Sample Type yp Penetration c_ Y N � ... Description of Units Page 1 of 1 Resistance U A a •" a°i Note: The, stratification lines shown represent the 0 �~ o `' ° c approximate boundary between soil and/or rock types Graphic Trend A m Cn (Blows/6") p t j and the transition may be gradational. Blow Count Dry Density SP -SM SAND WITH SILT: light olive gray, medium dense, dry, very fine to fine grained, some silt✓ ` 9,16;18 95 3 sand 5 5,10,18 damp to moist, fine grained 10 6,7,7 damp 15 y 5,8,9 Total Depth 19 feet 20 No groundwater encountered 25 30 35 40 45 50 55 _ ft Earth System Southwest Boring No: 79-81 IB Country Club. Drive, Bermuda Dunes, CA 92201 Phone (760) 345-1588 FAX (760) 345-7315 $-% Drilling Date: "October Project Name: SEC Avenue 52 & Jefferson Street, La Quinta, CA Drilling Method: 8" hollow stem auger File Number: 09386-01 Drill Type: CME 45 w/rope & cathead Boring Location: See Figure 2 Logged By: Karl Harmon Sample Penetration Description of Units Page 1 of 1 U.Type Resistance U Q a ." Note: The stratification lines shown represent the ,a, y o E �' ° c approximate boundary between soil and/or rock types Graphic Trend ' A m (Blows/6") p U and the transition may be gradational. Blow Count Dry Density SP -SM SAND WITH SILT: light olive gray, medium; dense, dry to damp, very fine to fine grained, some 8,11,13 92 2 silty sand 5 • SM SILTY SAND: light olive gray, medium dense,. 8,11;13 89 5 damp, very fine to fine grained; some sand with silt - 10 6,11,12 SP -SM SAND WITH SILT: light olive gray, medium; t5. damp, very fine to fine grained. Idense, 4,5,6 Total Depth -16.5 feet • No groundwater encountered 20 - - t 25 30 35 40 45 50 55 3, 2003 , a P: t r a P: File No,.; 09386-01 October. l.7, 2003 UNIT•DENSITIES AND MOISTURE CONTENT ASTM D2937 & D2216. •` Job Name: SEC Avenue 52 & Jefferson Bl 5 98 Unit Moisture USCS Sample Depth Dry Content Group Location (feet) Density.(pcf) (%) Symbol Bl 5 98 1 SIP -SM . • , . • BI 10 108 ; 1 SP -SM r ' B1 i •15 85 33 ML B2 2.5 - 95 3, SM - B2 7.5 _ 95 3 SM B3 5 96 1 SP. -SM B3 10. 97 4. SP -SM . B4 2.5 96 1 SM 4 B4 7:5 90 4 SM �. B5 2 85 1 SM B5 5 88 1 SM B5 10 92 3 SP -SM B6 2.5 95 3 SP -SM r. B7 2 92 2 - CP -SM B7 5. 89 .5 SM EARTH SYSTEMS SOUTHWEST File:No.: 093.86-01 October 17, 2003 PARTICLE SIZE ANALYSIS ASTM D-422 Job Name: SEC Avenue 52 & Jefferson Sample.ID:.B1 @ 2' Feet Description: 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 % Gravel: 0 #30 100 %.Sand: 86 #50 '90 % Silt: S #100 42 % Clay .(3 micron): 6 #200 - . 14 (Clay content by short hydrometer, method) ' 100 90 - - -- - - - - - — - - ------- 70 - - - - - - 60 - ---_- - -- -- - - '- 50 - - - ---- - - U ' y 40 - -. ....--- --.... --- - - - 30ET -- — -- 10 - - -- --- 0 " 100 10 I 0:1 0.0' Particle Size ( mm) 0.001 - EARTH SYSTEMS SOUTHWEST " File No.: 09.386-01 _ October 17, 2003 PARTICLE.SIZE ANALYSIS y + ASTM D-422 T t• . Job Name: -SEC Avenue 52 & Jefferson Sample ID: B3 @ 1-4' Feet r Description: Silty Sand: F (SM) ' Sieve Percent Size Passing . 1-1/2" 100 1 " 100 ' 3/4" 100 1/2" 1.00 3/8 100 #4, 100 #8 100 #16 100 % Gravel: 0 - ` #30 100 o Sand: 91 #50 92%Silt: "�2 t S. , 100 51 % Clay (3 micron): 7 #200. 19 • (Clay content.by short hydrometer method) 100 90 80 70 r e 60 (A 50 u L 40 y 30 20 10 0 4 ' File No.: 09386-01 October 17, 2003 CONSOLIDATION TEST ASTM D 2435 & D 5333 SEC"Avenue 52 & Jefferson Initial Dry Density: 84.6 pcf ` Bl @ 15' Feet Initial Moisture, %: 32.7% Silty (ML),Specific Gravity, (assumed): 2.67 ' Ring Sample Initial Void Ratio: 0:970 Hydrocollapse: 0:5% @ 2.0 ksf % Change in Height vs Normal Presssure Diagram Before Saturation Hydrocollapse �. 'After Saturation -Y'A-Rebound - 2 1 • 0 -I -3 -4 .a v " U u L a -7 -g -9 -10 -1'1 -12 File No.: 09386-01 October 17, 2003 , CONSOLIDATION TEST ASTM D 2435 & D 5333 SEC Avenue 52 & Jefferson Initial. Dry Density: 81.7 pcf. B5 @ 2' Feet Initial Moisture, ° o: 0.9% Silty Sand: F (SM) Specific Gravity (assumed): '2.67 Ring Sample Initial Void Ratio: 1.04.1 Hydrocollapse: 2.2% @ 2.0 ksf ' % Change. in Height vs Normal Presssure Diakram 2