Appendix E1 - Geotech Site B 4-1-13.pdf

7/28/2019 Appendix E1 - Geotech Site B 4-1-13.pdf

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~ CHJ Consultants1355 E. Cooley Drive. Suite C. Colton, CA -92324 Phone(909) 824-7311 Fax (909).5031136

15345Anacapa Road, SuiteD, Victorville, CA 92392 Phone {760) 2430506 fax(760) 243-122577-564A Country Club Drive, Suite 122, Palm Desert, CA 92211 Phone (760) 772-8234 Fax (909) 503c1136

County ofRiversideEconomic Development Agency3403 1Oth Street, Suite 500Riverside, California 92501Attention: Mr. Rizaldy Balayot

Dear Mr. Balayot:

April1, 2013

Job No. 13143-3

This letter transmits six copies of our Geotechnical Investigation report for the proposed East CountyDetention Center parking structure, to be located southeast of the intersection of Oasis Street andPlaza Avenue in the City of Indio, California

We appreciate this opportunity to provide geotechnical services for this project. If you havequestions or comments concerning this report, please contact this firm at your convenience.

Respectfully submitted,CHJCONSULTANTS


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G E O T E C ~ C A L I N V E S T I G A T I O NPROPOSED EAST COUNTY DETENTION CENTERPARKING STRUCTURE

SOUTHEAST OF OASIS STREETAND PLAZA AVENUEINDIO, CALIFORNIA

PREPARED FORCOUNTY OF RIVERSIDE

ECONONUCDEVELOPMENTAGENCYJOB NO. 13143-3


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~ * ~ CHJ Consultants~ 1355 E. Cooley Drive, Suite C. Colton, CA 92324 Phone (909) 824-7311 Fax (909) 503-113615345 Anacapa Road, Su ite D, Vctorville, CA 92392 Phone (760) 243-0506 Fax (760) 243-1225

77-564A Country Club Drive, Suite 122, Palm Desert, CA 92211 Phone (760) 772-8234 Fax (909) 503-1136

County ofRiversideEconomic Development Agency3403 1Oth Street, Suite 500Riverside, California 92501Attention: Mr. Rizaldy Balayot

Dear Mr. Balayot:

April 1, 2013

Job No. 13143-3

Attached herewith is the Geotechnical Investigation report, prepared for the proposed East CountyDetention Center parking structure, to be located southeast of the intersection of Oasis Street andPlaza Avenue in the City of Indio, California.

This report was based upon a scope of services generally outlined in our proposal, dated March 5,2013, and other written and verbal communications.

We appreciate this opportunity to provide geotechnical services for this project. If you havequestions or comments concerning this report, please contact this finn at your convenience.

Respectfully submitted,CHJCONSULTANTS


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TABLE OF CONTENTS

INTRODUCTION................................................................................................................. 1PROJECT CONSIDERATIONS........................................................................................... 2SCOPE OF SERVICES......................................................................................................... 2SITE DESCRIPTION............................................................................................................ 3FIELD INVESTIGATION.................................................................................................... 3LABORATORY INVESTIGATION.................................................................................... 4SITE GEOLOGY AND SUBSURFACE SOIL CONDITIONS........................................... 5FAULTING............................................................................................................................ 6

Fault Rupture Hazard Potential..................................................................................... 7Local and Regional Faults ............................. ..... ..... .. .......... ....... ... ....... ............ ............ 7San Andreas Fault Zone ........... .............. .......... ..... ....... ................. .......... .. ............ 7San Gorgonio Pass Fault Zone.............................................................................. 8Eureka Peak and Burnt Mountain Faults............................................................... 9Brawley Seismic Zone........................................................................................... 9San Jacinto Fault Zone.......................................................................................... 9Pinto Mountain Fault............................................................................................. 10HISTORICAL EARTHQUAKES......................................................................................... 10DESIGN ACCELERATION PARAMETERS...................................................................... 11GROUNDWATER................................................................................................................ 12LIQUEFACTION POTENTIAL AND SEISMIC SETTLEMENT...................................... 13SLOPE STABILITY AND LANDSLIDE POTENTIAL..................................................... 16FLOODING........................................................................................................................... 17SUBSIDENCE POTENTIAL................................................................................................ 17HYDROCONSOLIDATION................................................................................................. 18CONCLUSIONS.................................................................................................................... 18


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TABLE OF CONTENTS

Potential Erosion........................................................................................................... 28Expansive Soils............................................................................................................. 28Soil Corrosion............................................................................................................... 28Preliminary Flexible Pavement Design . . ... ............. . . . . . .. .. . . . 29Preliminary Rigid Pavement Design............................................................................. 30

SHALLOW FOUNDATION RECOMMENDATIONS....................................................... 32Preparation ofFooting Areas........................................................................................ 32Foundation Design........................................................................................................ 32Modulus ofSubgrade Reaction..................................................................................... 33Slabs-on-Grade............................................................................................................. 34DEEP FOUNDATION RECOMMENDATIONS................................................................. 34

Allowable Axial Pile Capacities................................................................................... 35Lateral Pile Analysis..................................................................................................... 36Pile Spacing and Group Efficiency............................................................................... 37CIDH Pile Installation................................................................................................... 39Pre-Job Conference....................................................................................................... 40Construction Observation ........ ......... ..... ........ ........ ................. ....... ....... ............ .. .......... 40LIMITATIONS ............:......................................................................................................... 41CLOSURE 42REFERENCES...................................................................................................................... 43AERIAL PHOTOGRAPHS REVIEWED............................................................................. 48


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TABLE OF APPENDICES

APPENDIX "A" - GEOTECHNICAL MAPSIndex Map........................................................................................................... "A-1"Site Plan.............................................................................................................. "A-2"Geologic Index Map........................................................................................... "A-3"Regional Fault Map............................................................................................ "A-4"Earthquake Epicenter Map................................................................................. "A-5"

APPENDIX "B"- EXPLORATORY LOGSKey to Logs ....................................................................................................... .Engineering Properties from SPT Blows .......................................................... .Soil Classification Chart ................................................................................... .Exploratory Boring Logs, East County Detention Center Parking Structure .... .

APPENDIX "C"- LABORATORY TESTINGParticle Size Distribution (ASTM D422) .......................................................... .Compaction Curves (ASTM D1557) ................................................................ .Consolidation Tests (ASTM D2435) ................................................................ .Direct Shear Tests (ASTM D3080) ................................................................... .Test Data Summary ........................................................................................... .Corrosivity Test Results .................................................................................... .R-Value Test. ..................................................................................................... .AC & PCC Structural Section Design .............................................................. .

APPENDIX "D" - GEOTECHNICAL CALCULATIONSLiquefaction Potential - SPT Data .................................................................... .Seismic Settlement Potential - SPT Data .......................................................... .Earth Pressures ..................................................................................................

APPENDIX "E"- PILE CALCULATIONSPile Results, 24-Inch Pile .................................................................................. .

"B" (1 of3)"B" (2 of3)"B" (3 of3)"B-1 "-"B-9"

"C-1""C-2""C-3""C-4"-"C-11 II"C-12""C-13""C-14""C-15"

"D-1 "-"D-3""D-4 I -"D-6""D-7"

"E-1 II- "E-3"


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GEOTECHNICAL INVESTIGATIONPROPOSED EAST COUNTY DETENTION CENTER PARKING STRUCTURESOUTHEAST OF OASIS STREET AND PLAZA A VENUEINDIO, CALIFORNIAPREPARED FORCOUNTY OF RIVERSIDEECONOMIC DEVELOPMENT AGENCYJOB NO. 13143-3

INTRODUCTION

During March and April of 2013, a geotechnical investigation was performed by this firm for theproposed East County Detention Center (ECDC) parking structure, to be located southeast of theintersection of Oasis Street and Plaza Avenue in the City of Indio, California. The purposes of thisinvestigation were to explore and evaluate the geotechnical engineering/engineering geologicconditions of the site and to provide appropriate geotechnical engineering and engineering geologicrecommendations for design and construction of the proposed development.

To orient our investigation at the site, an electronic copy of the 30-scale ECDC Parking StructureSpace Plan, dated January 22, 2013, prepared by Holt Architecture, was provided to us. GoogleEarth's aerial imagery was also utilized. The approximate location of the proposed facility is shownon the attached Index Map (Appendix "A").

C.H.J., Incorporated performed a geotechnical investigation for the County AdministrativeCenter/Law Library improvement project in 2008 (Job No. 08659-3, dated October 17, 2008). Ageotechnical investigation was performed by CHJ Consultants, Inc. for the ECDC project in 2012(Job No. 12643-3, dated October 23, 2012), proposed for construction northwest of the intersection ofPlaza Avenue and Oasis Street. Information obtained for these investigations was referenced during


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PROJECT CONSIDERATIONS

Page No.2Job No. 13143-3

It is our understanding, based on the Parking Structure Space Plan (dated January 22, 2013, preparedby Holt Architecture), that a three-level, multi-bay structure is being added to ECDC. The proposedparking structure will include 330 stalls per level with dimensions of approximately 240 feeteast-west and 474 feet north-south. The total footprint will occupy approximately 113,760 squarefeet.

The site is currently occupied by a paved parking lot.

Project grading plans were not available at the time of our investigation. However, observation ofsite topography and of adjacent developments indicates that development of this site will entail minorcuts and fills. The final project grading plan should be reviewed by the geotechnical engineer.

SCOPE OF SERVICES

The scope of services provided during this geotechnical investigation included the following:

Review of published and unpublished geologic literature, maps and prior pertinentgeotechnical/geologic reports prepared by C.H.J., Incorporated, CHJ Consultants and others

Review of aerial photographs flown between 1974 and 2011 Field reconnaissance of the site and surrounding area


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Evaluation of geologic hazards


Evaluation of the geotechnical data to develop site-specific recommendations for site grading, shallow and deep foundation design, preliminary asphalt concrete (AC) and Portlandcement concrete (PCC) pavement structural section design, and mitigation of potentialgeotechnical concerns and hazards, such as liquefaction and seismic settlement

SITE DESCRIPTION

The site is located east of Oasis Street and south of Plaza Avenue in the City of Indio, RiversideCounty, California, and is developed as an existing parking lot with associated infrastructure. Thesite is relatively level and is approximately 11 feet below mean sea level (msl). Evidence ofunderground utilities was observed throughout the site.

In the reviewed aerial photographs dated 1974, 1980 and 1984, the site appears to be largelyundeveloped, although several structures are present in the center and northern portions of the site.At those times, none of the subject site was paved. Aerial images dated 1996 show the site to be inits approximate present condition. No evidence of faulting or other geologic hazards was seen in theaerial photographs reviewed or at the site during the geologic reconnaissance.

No other surface features pertinent to this investigation were noted.

FIELD INVESTIGATION


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Continuous logs of the subsurface conditions, as encountered within the exploratory borings, wererecorded at the time of drilling by a staff geologist from this firm. Both a standard penetration test(SPn sampler (2-inch outer diameter and 1-3/8-inch inner diameter) and a modified California sampler (3-inch outer diameter and 2-3/8-inch inner diameter) were utilized in our investigation.Relatively undisturbed samples were obtained by driving the modified California sampler (asplit-spoon ring sampler) ahead of the borings at selected levels. The penetration resistance wasrecorded on the boring logs as the number of hammer blows used to advance the sampler in 6-inchincrements (or less if noted). Samplers are driven with an automatic hammer that drops a140-pound weight 30 inches for each blow. After the required seating, the sampler is advanced upto 18 inches, providing up to three sets of blowcounts at each sampling interval. The recordedblows are raw numbers without any corrections for hammer type (automatic vs. manual cathead) orsampler size (California sampler vs. SPT sampler). Relatively undisturbed as well as bulk samplesof typical soil types obtained were returned to the laboratory in sealed containers for testing andevaluation.

Our exploratory boring logs, together with our in-place blowcounts per 6-inch increment, are presented in Appendix "B". The stratification lines presented on the boring logs represent approximateboundaries between soil types, which may include gradual transitions.

LABORATORY INVESTIGATION

Included in our laboratory testing program were field moisture content tests on all samples returnedto the laboratory and field dry density tests on all relatively undisturbed ring samples. The results


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contents for liquefaction and seismic settlement analyses. Atterberg limits testing was conducted onselected clay-like soils as an aid to classification. An expansion index test was performed on aselected sample to evaluate the expansion potential of the on-site soils.

Sieve analyses, sand equivalent tests and R-value tests were performed on probable pavement subgrade soils to develop criteria for preliminary pavement design recommendations. Selected samplesof materials were delivered to HDRISchiff for chemical/corrosivity testing.

Summaries of the laboratory test results appear in Appendix "C". Soil classifications provided inour geotechnical investigation report are generally per the Unified Soil Classification System(USCS).

SITE GEOLOGY AND SUBSURFACE SOIL CONDITIONS

The site is located in the central Coachella Valley in the Colorado Desert geomorphic province. TheCoachella Valley extends southeastward from the San Gorgonio Pass to the Salton Sea region and istraversed by segments of the San Andreas fault zone. The lowland of the Coachella Valley accumulates sediments from surrounding highlands in the form of alluvial and eolian (wind-deposited)materials. The valley in the area of the site is bounded on the southwest by the San Jacinto andSanta Rosa mountains and on the northeast by the Indio Hills. The channel of the Whitewater Riveris located about 1-1/4 miles northeast of the site. According to published geologic mapping(Dibblee, 2008, Enclosure "A-3"), the site is underlain by alluvial sand and clay.


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Fill classified as silty sand (SM) was encountered in all of our exploratory borings to depths rangingfrom approximately 3 to 7 feet bgs.

Groundwater was encountered within Exploratory Boring Nos. 1, 2 and 3 at depths of 70, 70, and69 feet bgs, respectively.

Refusal to further advancement of the drill auger was not experienced in any of the exploratoryborings.

Bedrock was not encountered within the exploratory borings.

No caving of the boring walls in the upper 10 feet of the borings was observed upon removal of theaugers.

A graphic depiction of the subsurface soil conditions encountered is presented on the attached boringlogs (Appendix "B ").

Expansion testing performed on samples of silt-bearing soil indicated a "very low" potential forexpansion when tested as per ASTM D4829.

The results of corrosivity testing are discussed in the "Soil Corrosion" section of this report.

FAULTING


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FAULT RUPTURE HAZARD POTENTIAL:

PageNo. 7Job No. 13143-3

The site is not located within an Alquist-Priolo Earthquake Fault Zone (APZ) designated by the Stateof California for active faults. According to the County of Riverside General Plan (2005) and Cityof Indio General Plan (2006), faults are not located beneath the site. The closest APZ, designatedfor faults of the Coachella segment of the San Andreas fault zone, is located approximately 4 kilometers (2.5 miles) northeast of the site. Active faults are not mapped within or projecting through thesite, and evidence of faulting was not observed in the aerial imagery reviewed. Therefore, thepotential for fault rupture beneath the site is considered low.

LOCAL AND REGIONAL FAULTS:The tectonics of the Southern California area are dominated by the interaction of the North Americanplate and the Pacific plate, which are sliding past each other in a translational manner. Althoughsome of the motion may be accommodated by rotation of crustal blocks such as the western Transverse Ranges (Dickinson, 1996), the San Andreas fault zone is thought to represent the major surfaceexpression of the tectonic boundary and to be accommodating most of the translational motionbetween the Pacific plate and the North American plate. However, some of the plate motion isaccommodated by other northwest-trending, strike-slip faults that are thought to be related to the SanAndreas system, such as the San Jacinto fault and the Elsinore fault. Local compressional or extensional strain resulting from the translational motion along this boundary is accommodated byleft-lateral, reverse and normal faults (Matti and others, 1992; Morton and Matti, 1993). A mapshowing the site in relation to regional faults is presented in Appendix "A" (Enclosure "A-4").

San Andreas Fault Zone


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of two main sub-parallel strands. The closest mapped trace of the San Andreas fault is locatedapproximately 4.3 kilometers (2-3/4 miles) northeast of the site. The San Andreas fault is characterized by youthful fault scarps, vegetational lineaments, springs and offset drainages. The WorkingGroup on California Earthquake Probabilities (1995) tentatively assigned a 28 percent (13 percent)probability to a major earthquake occurring on the San Bernardino Mountains segment of the SanAndreas fault between 1994 and 2024. More recent studies of the southern segment of the SanAndreas fault, which includes the portion located near the site, suggest that the southern segment iscapable ofproducing a large earthquake (Fialko, 2006).

The Mission Creek, Banning and Gamet Hill segments of the San Andreas fault zone branch from theCoachella Valley segment at a point located approximately 7 kilometers (4-1/2 miles) north of thesite. Multiple fault strands distributed across a zone approximately 500 meters wide with conc.entrated faulting in a 200-meter-wide zone are interpreted for the Mission Creek fault in the Desert HotSprings area based on seismic imaging studies (Catchings et al., 2009). Near-surface strands of theMission Creek fault form a groundwater barrier and converge at depth into a vertical tosouthwest-dipping fault zone (Catchings et al., 2009). The Banning fault dips toward the MissionCreek fault located to the northeast, forming a single fault zone at depth (Catchings et al., 2009).

The SAFZ is considered the most important fault with respect to the potential to produce strongground shaking at the site.

San Gorgonio Pass Fault ZoneThe active San Gorgonio Pass fault zone (SGPFZ), located in the San Gorgonio Pass area approxi


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faults that roughly parallel Interstate 10 and bound the mountain front between Banning andWhitewater River (Yule and Sieh, 2003).

Eureka Peak and Burnt Mountain FaultsThe Eureka Peak and Burnt Mountain faults were revealed as a result of surface rupture along thesouthern portion of the Landers earthquake rupture system. The faults are located approximately29 kilometers (18 miles) north-northwest of the site and are thought to be significant in transferringslip from the SAFZ into the Eastern California shear zone. Geologic investigations suggest that thelast pre-Landers earthquake to occur on the Eureka Peak fault was more than 11,000 years before thepresent (Yucca Valley, 1995).

Brawley Seismic ZoneThe Brawley seismic zone is a linear zone of seismicity that includes surface and concealed faultslocated approximately 105 kilometers (66 miles) south-southeast of the site. The Brawley seismiczone is associated with a right step between the Imperial fault zone and San Andreas fault zone,forming an inferred spreading center segment beneath the Imperial Valley (Treiman, 1999). Earthquake swarms associated with the Brawley zone occurred in 1975, 1981, 2005 and most recently inAugust/September 2012.

San Jacinto Fault ZoneThe San Jacinto fault zone is a system of northwest-trending, right-lateral strike-slip faults. TheAnza/Clark segment of the San Jacinto fault zone is located approximately 35 kilometers (22 miles)southwest of the site and is associated with the moment magnitude (Mw) 6.4 San Jacinto earthquake


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Page No. 10Job No. 13143-3

on the San Bernardino Valley segment of the San Jacinto fault for the 30-year interval from 1994 to2024.

Pinto Mountain Faul tThe Pinto Mountain fault is a left lateral, strike-slip fault system trending eastward approximately28 kilometers (45 miles) from the eastern San Bernardino mountains to the Twentynine Palms area(Jennings, 1994). The closest portion of the fault to the site is located approximately 48 kilometers(29 miles) northwest of the site. This fault exhibits Holocene-age activity and experienced triggeredslip during the 1992 Landers earthquake event. Portions of the Pinto Mountain fault are includedwithin Alquist-Priolo Earthquake Fault Zones designated by the State of California.

IDSTORICAL EARTHQUAKES

A map of recorded earthquake epicenters is included as Enclosure "A-5" (Epi Software, 2000). Thismap includes the California Institute of Technology database for earthquakes with magnitudes of 4.0or greater from 1932 through 2011.

The Working Group on California Earthquake Probabilities (1988) lists seven Mw 6.0 or greaterearthquakes that have occurred on the San Jacinto fault since 1899, although they acknowledge thatseveral of the earlier episodes may have occurred on other nearby faults. The Clark segment of theSan Jacinto fault zone is associated with the Mw 6.4 San Jacinto earthquake of 1954. The mostrecent surface rupture along the San Jacinto fault zone occurred in 1968 along the Coyote Creek segment during an Mw 6.5 earthquake. Two earthquakes took place in the San Bernardino Valley.


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The Coachella Valley segment of the San Andreas fault was the locus for the 1948 Mw 6.5 earthquake in the Desert Hot Springs area and for the 1986 Mw 5.6 earthquake in the North Palm Springsarea. Surface rupture occurred on the Mojave segment of the San Andreas fault in the great 1857Fort Tejon earthquake. Using dendrochronological evidence, Jacoby and others (1987) inferred thata great earthquake on December 8, 1812, ruptured the northern reaches of the San Bernardino Mountains segment. Recent trenching studies have revealed evidence of rupture on the San Andreas faultat Wrightwood within this time frame (Fumal and others, 1993). Comparison of rupture events atthe Wrightwood site and Pallett Creek, and analysis of reported intensities at the coastal missions, ledFumal and others (1993) to conclude that the December 8, 1812, event ruptured the San BernardinoMountains segment of the San Andreas fault largely to the southeast of Wrightwood, possibly extending into the San Bernardino Valley.

Surface slip/rupture occurred on the Burnt Mountain and Eureka Peak faults during the Landersearthquake sequence in 1992. These relatively short faults are postulated to produce moderateearthquakes of magnitude 6.4 to 6.7 during independent earthquake events.

Significant historic earthquakes have not specifically been attributed to the Pinto Mountain fault orSan Gorgonio Pass fault zone. The magnitude 7.3 Landers earthquake occurred June 28, 1992,approximately 64 kilometers (40 miles) northwest of the site. The Mw 7.1 Hector Mine earthquakeoccurred on October 16, 1999, approximately 97 kilometers (60 miles) north of the site.

DESIGN ACCELERATION PARAMETERS


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Table 1

PageNo.12Job No. 13143-3

Design Acceleration ParametersMapped Spectral Acceleration Parameters Ss = 1.71 and S1 = 0.69

Site Coefficients Fa= 1.0 and Fv = 1.5Adjusted Maximum Considered Earthquake SMs = 1.71 and SM1 = 1.04Spectral Response Parameters

Design Spectral Acceleration Parameters Sos = 1.14 and Sm = 0.69

The corresponding value of peak ground acceleration (PGA) from the design response spectrum is0.46g. Based on the design spectral acceleration parameters and ASCE 7-05, the project is considered Seismic Design Category "D".

GROUNDWATER

The site is located in Section 26 of Township 5 South, Range 7 East in the Thermal subarea of theWhitewater subbasin of the Coachella Valley Groundwater Basin. Groundwater data in the vicinityof the site are summarized in the following table.

Table 2Depth to Water LocationDate SurfaceDataiD Measured Water Elevation of Reference


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Groundwater was encountered at depths of 70, 70, and 69 feet bgs in Boring Nos. 1, 2 and 3 in ourcurrent borings at the site.

Based on the available historic and recent groundwater data for the site and the anticipated groundwater conditions during the project lifetime, the depth to historic high groundwater is 20 feet bgs.

LIQUEFACTION POTENTIAL AND SEISMIC SETTLEMENT

According to the County of Riverside (2012) and the City of Indio (2006), the site is located withinan area identified as having a potential for liquefaction based on the potential for shallowgroundwater.

Liquefaction is a process in which strong ground shaking causes saturated soils to lose their strengthand behave as a fluid (Matti and Carson, 1991). Ground failure associated with liquefaction canresult in severe damage to structures. Soil types susceptible to liquefaction include sand, silty sand,sandy silt and silt, as well as soils having a plasticity index (PI) less than 7 (Boulanger and Idriss,2006). Loose soils with a PI less than 12 and moisture content greater than 85 percent of the liquidlimit are also susceptible to liquefaction (Bray and Sancio, 2006). For sandy soils, the geologicconditions for increased susceptibility to liquefaction are: 1) shallow groundwater (generally lessthan 50 feet in depth), 2) the presence of unconsolidated sandy alluvium, typically Holocene in age,and 3) strong ground shaking. All three of these conditions must be present for liquefaction tooccur.


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softening' and 'liquefaction' can also be used in reference to the engineering procedures that havebeen developed for these respective soil types" (Idriss and Boulanger, 2008).

Due to the potential for the presence of shallow groundwater beneath the site (20 feet), theliquefaction potential of the site has been evaluated based on the SPT and cone penetrometer test(CPT) data obtained and using the simplified procedure described by Seed and Idriss (1982), Seedand others (1985), modified in the 1996 National Center for Earthquake Engineering Research(NCEER) and 1998 NCEER!National Science Foundation (NSF) workshops (Youd and ldriss, 2001)and recently summarized by ldriss and Boulanger (2008). The method of evaluating liquefactionpotential consists of comparing the cyclic stress ratio (CSR) developed in the soil by the earthquakemotion to cyclic resistance ratio (CRR), which will cause liquefaction of the soil for a given numberof cycles. In the simplified procedure, the CSR developed in the soil is calculated from a formulathat incorporates ground surface acceleration, total and effective stresses in the soil at different depths(which in turn are related to the location of the groundwater table), non-rigidity of the soil columnand a number of simplifying assumptions.

For sandy soils, the CRR that will cause liquefaction is related to the relative density of the soil,expressed in terms of SPT blowcounts (N1)6o (Seed and Idriss, 1982; Seed and others, 1985; Youdand Idriss, 2001; Idriss and Boulanger, 2008), cone penetration resistance (qciN) (Robertson andWride, 1998; Youd and ldriss, 2001; Idriss and Boulanger, 2008) or shear wave velocity (V 51 )(Andrus and Stokoe, 2000; Youd and ldriss, 2001; Andrus and others, 2004), all normalized for aneffective overburden pressure of 1 ton per square foot and corrected to equivalent clean sandresistance. For clayey soils, the CRR is related to cyclic undrained shear strength ratio, suiGvc'


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Prediction of seismic-induced settlement is also very important. Seismic-induced settlementincludes settlement that occurs both in dry sands and saturated sands (California Geological Survey,2008). Severe seismic shaking may cause dry sands to densify, resulting in settlement expressed atthe ground surface. Seismic settlement in dry soils generally occurs in loose sands and silty sands,with cohesive and fine-grained soils being less prone to significant settlement. For saturated soils,significant settlement is anticipated if the soils exhibit liquefaction during seismic shaking.

The methods for evaluating seismic settlement in saturated sands can generally be classified into twogroups. The method for the first group was developed during the 1970s and 1980s, generally basedon the relationship between cyclic stress ratio, CNt)6o, and volumetric strain (Silver and Seed, 1971;Lee and Albaisa, 1974; Tokimatsu and Seed, 1987). The method for the second group wasdeveloped in the early 1990s with the paper by Ishihara and Yoshimine (1992) as the first publicationin the category, modified and improved by various researchers (Robertson and Wride, 1998;Yoshimine et al., 2006; Idriss and Boulanger, 2008; and Yi, 2010a), and is generally based on therelationship between volumetric strain and the factor of safety for liquefaction. ldriss andBoulanger (2008) modified the methods to incorporate both SPT and CPT data. Yi (2010b, 2010c)modified the methods to incorporate shear wave velocity data.

Research related to the estimation of dry sand settlement during earthquake excitation was initiated inthe early 1970s by Silver and Seed (1971), followed by the works of several researchers (Seed andSilver, 1972; Pyke et al., 1975; Tokimatsu and Seed, 1987; Pradel, 1998). A simplified method ofevaluating earthquake-induced settlements in dry, sandy soils based on the Tokimatsu and Seedprocedure has been developed by Pradel (1998) and is recommended by Martin and Lew (1999) as


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modified method for CPT data (Yi, 2010a). All of these methods were incorporated into aliquefaction and seismic settlement program, GeoSuite 2008, version 2.2 (Yi, 2013).

Liquefaction potential was evaluated for the soil profiles encountered in exploratory borings using anSPT sampler. Seismic settlement was estimated for the same soil profiles utilized in the liquefactionanalyses. The results of liquefaction potential and seismic settlement evaluations are shown inEnclosures 11D-1 11 through 110-6 11

Our calculations indicate that liquefaction could occur within thin localized layers. However, overall, liquefaction potential is considered to be insignificant. Our analysis indicates that seismic settlement (including liquefaction-induced settlement and dry sand settlement) could range from approximately 1.3 to 2.0 inches based on SPT data soil profiles using the Idriss and Boulanger (2008)method. We estimate a maximum seismic settlement of 2 inches and a maximum seismicdifferential settlement of 3/8 inch over 40 feet. Seismic settlement will generally occur in soil layersbelow 20 feet bgs to as deep as 65 feet bgs.

Examination of the liquefaction analysis results indicates that the maximum thickness of the liquefiable layer (H2) was 5 feet. According to Ishihara (1985), the surface manifestation of liquefaction(such as boils, ground fissure, etc.) can be minimized by adequate thickness of the non-liquefiablecrust (H1) at the site. For the thickness of the liquefiable layer (H2) of 5 feet, Ishihara's charts indicates that the surface manifestation effects on the structure will be absent if the non-liquefiable crustis thicker than 13.5 feet for a maximum ground acceleration of0.4 to 0.5g. Based on these data, it isthe opinion of this firm that the surface manifestation effects of liquefaction on the structure will be


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parking structure regulations. The soils on-site are considered to be Type C with regard to CALOSHA excavation standards. The potential for landsliding or lateral spreading is considered to bevery low.

FLOODING

Evidence of recent flooding of the site and surrounding area was not observed on the aerial photographs reviewed. As depicted on Flood Insurance Rate Map No. 06065C2253G (FEMA, 2008)dated August 28, 2008, the site is located in a shaded zone "X". This zone is described in the maplegend as:

"Zones B and X (shaded) are areas of 0.2-percent-annual-chance floodplain, areas of1-percent-annual-chance (base flood) sheet flow flooding with average depths of less than 1foot, areas of base flood stream flooding with a contributing drainage area of less than 1square mile, or areas protected from the base flood by levees. No Base Flood Elevation (BFEs)or depths are shown in this zone, and insurance purchase is not required."

According to the County of Riverside (2012), the site is not located within a potential inundationzone for seismically induced dam/reservoir failure from dams or reservoirs. The site is not locatedin a coastal area. No large water storage facilities are known to exist within the area of the site.Therefore, the potential for precipitation-induced or seismically induced flooding due to dam failureor seiche to affect the site is considered to be low.


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Valley since the 1970s, resulting in increased groundwater pumping and groundwater level declines.By 2005, levels in many wells in the East Valley area had declined 50 to 100 feet.

Land subsidence studies by Ikehara and others (1997) reported that subsidence may have been asmuch as 1/2 foot in the southern parts of Coachella Valley between 1930 and 1996. A more recentstudy (Sneed, 2010) documented three main areas of subsidence in the Coachella Valley: the PalmDesert, Indian Wells and La Quinta areas. The site is not located within a documented subsidencearea. The 2007 report did not establish a direct relation between subsidence and groundwaterpumping/declining water levels; however, the 2010 report suggests a direct relationship betweenwater level declines and subsidence in the Coachella Valley region.

Ground subsidence alone is not expected to pose a significant hazard to the project. Groundcracking may be a potential hazard should significant subsidence occur in the future. The potentialfor significant subsidence during the lifetime of the project is considered to be low to very low.

HYDROCONSOLIDATION

To evaluate the potential deformation that may be caused by the addition of water, hydroconsolidation tests were performed on selected, representative relatively undisturbed samples. The results areshown in Enclosure "C-3". Based on the test results, the site soils have moderatehydroconsolidation potential.

CONCLUSIONS


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Moderate to severe seismic shaking can be expected at the site.


No evidence of recent significant flooding of the site was observed dwing the field reconnaissance oron the aerial images reviewed. The upper soils encountered within the site consist of silty sands andsilt that are moderately susceptible to erosion by wind and water.

Groundwater was encountered at depths ranging from 69 to 70 feet bgs in our exploratory borings atthe site. The historical high groundwater depth for this site is 20 feet. Liquefaction could occurwithin localized thin layers during the design earthquake. Because of the adequate thickness of thenon-liquefiable crust at the site, surface manifestation effects of liquefaction on the structure will beminimal. However, seismic settlement and differential settlement are anticipated.

Refusal to further advancement of the drilling augers was not experienced.

Slight caving was noted within the exploratory borings utilized for this investigation; trenches, largerdiameter borings or excavations that remain open for longer periods of time may be subject to caving.

Bedrock was not encountered in any of our exploratory borings.

Fill classified as silty sand (SM) was encountered to depths of 3 to 7 feet below existing grade in theexploratory borings. Additional areas of fill may be present between boring locations within thesite.


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The site is not within a documented subsidence area. Should significant subsidence occur in thefuture, ground cracking may be a potential hazard. The hazard is considered to be low to very low.

Based on the expansion index test results, significant expansion is not anticipated.

Hydroconsolidation test results indicate moderate hydrocollapse potential.

Based upon our field investigation and test data, it is our opinion that the near-surface soils, undocumented fill and underlying native soils in their present condition will not provide uniform or adequatesupport for the proposed structure or other site improvements.

Settlement resulting from seismic shaking may be on the order of2 inches and 3/8 inches over 40 feetdifferentially. Static settlement from anticipated foundation loading may result in a total settlementon the order of 1 inch and a differential settlement of approximately one half of the total. Due to thepresence of relatively deep undocumented fills and loose native soils, we are recommendingsubexcavation of the upper 8 feet of existing soils and replacement as properly compacted fill withinthe proposed parking structure area if the structure is to be supported by conventional shallowfoundations.

Subexcavation to a minimum depth of 3 feet within remaining settlement-sensitive areas to be graded(parking areas, hardscape areas and any other settlement-sensitive areas) is recommended. Thisrecommended subexcavation operation should include removal of any undocumented fills andobservation of the exposed surface by the project geologist or geotechnical engineer prior to pro


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the structure pad area include the parking structure area to a distance of 10 feet beyond footings,where possible.

The mandatory removal and replacement of the upper 8 feet of existing soil will accommodate footings as deep as 5 feet below existing grade. If footings extending beyond a depth of 5 feet are proposed, additional removal and replacement will be necessary to provide the recommended fill matthickness.

GENERAL RECOMMENDATIONS

SEISMIC DESIGN CONSIDERATIONS:Based on the geologic setting and anticipated earthwork for construction of the proposed project, thesoils underlying the site are classified as Site Class "D, stiff soil profile", according to the 2010 CBCand ASCE 7-05. The design acceleration parameters are summarized in the table below.

Table3Design Acceleration Parameters

Mapped Spectral Acceleration Parameters ss = 1.71 and sl = 0.69Site Coefficients F = 1.0 and F = 1.5a v

Adjusted Maximum Considered Earthquake SMs = 1.71 and SM1 = 1.04Spectral Response ParametersDesign Spectral Acceleration Parameters S05 = 1.14 and S01 = 0.69


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Observation, testing, documenting and reporting of the grading operation should be performed by thegeotechnical engineer of record. A final compaction report should be issued by the geotechnicalengineer of record at the completion of the grading operation. Operations undertaken at the sitewithout the geotechnical engineer present may result in exclusion of affected areas from the fmalcompaction report for the project.

Grading of the subject site should be performed, at a minimum, in accordance with theserecommendations and with applicable portions of the 2010 CBC. The following recommendationsare presented for your assistance in establishing proper grading criteria.

INITIAL SITE PREPARATION:All areas to be graded should be stripped of significant vegetation and other deleterious materials.These materials should be removed from the site for disposal. Any existing utility lines should betraced, removed and rerouted from areas to be graded.

Any existing undocumented fills encountered during grading should be completely removed from allareas to be graded and cleaned of significant deleterious materials; they may be reused as compactedfill.

To assist in undocumented fill and/or loose native soil identification and removal, it is our opinionthat all areas to be graded should be subexcavated to a minimum depth of 3 feet bgs. Depending onthe foundation type selected, additional removal may be necessary. If conventional shallow foundations are utilized, all loose material in the parking structure pad area should be completely removed.


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Removal depths greater than 8 feet may be necessary. An engineering geologist from this firmshould be present during the subexcavation operation prior to scarification and refilling in order toidentify existing fills or loose soils extending below this depth. A relative compaction of at least85 percent may be utilized as preliminary quantitative criteria to supplement the engineeringgeologist's qualitative evaluation of suitable base of excavation. The bottoms of all excavationsshould be observed and approved by the engineering geologist.

If deep foundations are utilized, all undocumented fill in the parking structure pad area should becompletely removed. A minimum removal of 3 feet should be performed. The removal shouldextend beyond the foundation edge at the bottom of the excavation to a distance of 10 feet, wherepossible.

In addition, it is our recommendation that all existing undocumented fills and loose soils under anyproposed paved or other flatwork areas be removed and replaced with properly compacted andcontrolled fills. If this is not done and any undocumented fills are left, premature structural distressof the paved and flatwork areas can be expected.

Cavities created by removal of subsurface obstructions should be thoroughly cleaned of loose soil,organic matter and other deleterious materials; shaped to provide access for construction equipment;and backfilled as recommended for site fill.PREPARATION OF FILL AREAS:The bottoms of the excavations should be observed by the engineering geologist to verify the


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COMPACTED FILLS:


The on-site soils should provide adequate quality fill material, provided they are free from organicmatter and other deleterious materials.

Import fill, if needed, should be inorganic, non-expansive, granular soil free from rocks or lumpsgreater than 6 inches in maximum dimension. Sources for import fill should be observed andapproved by the geotechnical engineer prior to their use.

Fill should be spread in near-horizontal layers, approximately 8 inches in thickness. Thicker liftsmay be approved by the geotechnical engineer if testing indicates that the grading procedures are adequate to achieve the required compaction. Each lift should be spread evenly, thoroughly mixed during spreading to attain uniformity of the material and moisture in each layer, brought to near optimummoisture content and compacted to a minimum relative compaction of 95 percent in accordance withASTM 01557. Our experience on nearby projects with similar soil conditions indicates that propermixing of the soils to obtain the desired moisture content is critical in obtaining the desiredcompaction.

It should be noted that very moist soils were encountered during our investigation. These soils weregenerally deeper than the anticipated excavation depths; however, very moist, near-surface soils maybe encountered during grading. Such soils will require specialized grading techniques such asspreading, drying and mixing to obtain the recommended moisture content.

Based upon the relative compaction of the native soils tested during this investigation and the relative


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Values presented for shrinkage and subsidence are estimates only. Final grades should be adjustedand/or contingency plans to import or export material should be made to accommodate possiblevariations in actual quantities during site grading.

It is crucial that the geotechnical engineer be present to observe these operations. Furtherrecommendations may be made in the field, depending on the actual conditions encountered.

LATERAL LOADING:Resistance to lateral loads will be provided by passive earth pressure and base friction. For footingsbearing against compacted fill, passive earth pressure may be considered to be developed at a rate of350 pounds per square foot (psf) per foot of depth. Base friction may be computed at 0.36 times thenormal load. Base friction and passive earth pressure may be combined without reduction.

Other than conservative soil modeling, the lateral passive earth pressure and base friction valuesrecommended do not include factors of safety. I f the design is to be based on allowable lateralresistance values, we recommend that minimum factors of safety of 1.5 and 2.0 be applied to the friction coefficient and passive lateral earth pressure, respectively. The resulting allowable lateralresistance values are:

Table 4Ultimate Allowable Factor of Safety

Passive Lateral Earth Pressure (psf/ft) 350 175 2.0


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typical earth pressure distributions are included in Enclosure "D-7" for an assumed wall height of15 feet.

For restrained conditions, an at-rest earth pressure of 60 ps f per foot of depth should be utilized.The "at-rest" condition applies toward braced walls that are not free to tilt. The "active" conditionapplies toward unrestrained cantilevered walls where wall movement is anticipated. The structuraldesigner should use judgment in determining the wall fixity and may utilize values interpolatedbetween the "at-rest" and "active" conditions where appropriate.

For walls 10 feet high or less, a uniform construction surcharge load of 72 ps f or an alternative trafficsurcharge load of 100 ps f should be applied in addition to active earth pressure. For walls higherthan 10 feet, a uniform construction surcharge load of 72 psf or an alternative traffic surcharge loadof 100 psf should be applied only up to 10 feet. The resulting additional surcharge pressure shouldbe applied to the wall as a rectangular distribution, from top to bottom, or 10 feet, whichever issmaller.

These values should be verified prior to construction when the backfill materials and conditions havebeen determined. These values are applicable only to level, properly drained backfill with no additional surcharge loadings and do not include a factor of safety other than conservative modeling ofthe soil strength parameters. If inclined backfills are proposed, this firm should be contacted todevelop appropriate active earth pressure parameters. If import material is to be utilized for backfill,an engineer from this fum should verify the backfill has equivalent or superior strength values.


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1. A 4-inch diameter perforated PVC (Schedule 40) pipe or equivalent at the base ofthe stemencased in 2 cubic feet ofgranular drain material per linear foot ofpipe or2. Synthetic drains such as Enkadrain, Miradrain, Hydraway 300 or equivalent.

Perforations in the PVC pipe should be 3/8 inch in diameter. Granular drain material should bewrapped with filter cloth such as Mirafi 140 or equivalent to prevent clogging of the drains with fines.Wails should be waterproofed to prevent nuisance seepage. Water should outlet to an approveddrain.

SEISMIC LATERAL EARTH PRESSURE:The seismic earth pressure acting on a cantilevered retaining wall was calculated by theMononobe-Okabe ("M-0") method (Okabe, 1926; Mononobe and Matsuo, 1929). It is recommended by AASHTO (LRFD Bridge Design Specifications, Fifth Edition, 2010, Section Cll.8.6)that the pseudostatic horizontal seismic coefficient (kh) be taken equal to kh=0.50xPGA=0.23g. Thepseudostatic vertical seismic coefficient (kv) is usually taken as one-half of kh. For retaining wallswith on-site soils as backfill materials, a unit weight of 119 pounds per cubic foot (pet) and a frictionangle of 30 degrees were utilized in the calculation. These values should be verified prior toconstruction when the backfill materials and conditions have been determined and are applicable onlyto level, properly drained backfill with no additional surcharge loadings.

A total lateral active seismic earth pressure (including static active earth pressure) developed at a rate


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The above lateral earth pressures are for level backfill. If inclined backfills are proposed, this firmshould be contacted.

POTENTIAL EROSION:The potential for erosion should be mitigated by proper drainage design. Water should not beallowed to flow over graded areas or natural areas so as to cause erosion. Graded areas should beplanted or otherwise protected from erosion by wind or water.

EXPANSIVE SOILS:Silty soil materials tested during this investigation exhibited a "very low" potential for expansion(expansion index of 2) in accordance with ASTM D4829. The results of these tests are presented inthe Appendix "C". Based on these results, it is the opinion of this firm that special structural designand/or construction procedures to specifically mitigate the effects of expansive soil movements arenot necessary. Requirements for reinforcing steel to satisfy structural criteria are not affected bythis recommendation. Additional evaluation of soils for expansion potential should be conducted bythe geotechnical engineer during construction.

SOIL CORROSION:Selected samples of material were delivered to our subconsultant, HDRISchiff, for soil corrosivitytesting. Laboratory testing consisted of pH, resistivity and major soluble salts commonly found insoils. The results of the laboratory tests appear in Enclosure "C-13 ". These tests have beenperformed in order to screen the site for potentially corrosive soils.


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Results of the soluble sulfate testing indicate a "negligible" anticipated exposure to sulfate attack, asindicated in Appendix "C". Based upon the criteria from Table 4.3.1. of the American ConcreteInstitute Manual of Concrete Practice (2000), no special measures, such as specific cement types,water-cement ratios, etc., will be needed for this "negligible" exposure to sulfate attack.

Soluble chloride content of soil was not at levels high enough to be of concern with respect to corrosion of ferrous materials. It was, however, at levels high enough to be of concern with respect tocorrosion of reinforcing steel. The results should be considered in combination with the solublechloride content of the hardened concrete in determining the effect of chloride on the corrosion ofreinforcing steel.

Ammonium contents did not indicate a concern with respect to corrosion of buried copper, whilenitrate contents did.

CHJ Consultants does not practice corrosion engineering. If further information concerning thecorrosion characteristics or if interpretation of the results submitted herein is required, then acompetent corrosion engineer should be consulted.

PRELIMINARY FLEXIBLE PAVEMENT DESIGN:

The following recommended structural sections were calculated based on traffic indices (Tis) provided in the Caltrans Highway Design Manual for Safety Roadside Rest Areas (Caltrans, 2008).Based upon our preliminary sampling and testing, the structural sections tabulated below should provide satisfactory AC pavement.


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UsageAuto Parking Areas

Auto RoadsTruck Parking AreasTruck Ramps and Roads

HMA = hot mix asphalt

Table 5TI R-value5.0 505.5 506.0 508.0 50

AB = aggregate base


Recommended Structural Section0.25' HMA/0.35' Class 2 AB0.25' HMA/0.35' Class 2 AB0.25' HMA/0.35' Class 2 AB0.40' HMA/0.45' Class 2 AB

Recommended structural sections were calculated based on Tis and our preliminary sampling andtesting. For other Tis, the structural sections provided in Enclosure "C-15" should providesatisfactory AC pavement.

The structural sections are predicated upon proper compaction of the utility trench backfills and thesubgrade soils, with the upper 6 inches of subgrade soils and all aggregate base material brought to aminimum relative compaction of95 percent in accordance with ASTM D1557 prior to paving. Theaggregate base should meet Caltrans requirements for Class 2 base.

PRELIMINARY RIGID PAVEMENT DESIGN:Based upon an R-value of 50, we recommend the following PCC pavement designs. These designsare based upon the ACI "Guide for Design and Construction of Concrete Parking Lots" (ACI 330R).


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The recommended concrete sections are based on adesign life of 20 years, with integral curbs orthickened edges. In addition, the above structural sections are predicated upon proper compactionof the utility trench backfills and the subgrade soils, with the upper 12 inches of subgrade soilsbrought to a uniform relative compaction of95 percent (ASTM 01557).

Slab edges that will be subject to vehicle loading should be thickened at least 2 inches at the outsideedge and tapered to 36 inches back from the edge. Typical details are given in the ACI "Guide forDesign and Construction of Concrete Parking Lots" (ACI 330R). Alternatively, slab edges subjectto vehicle loading should be designed with dowels or other load transfer mechanisms. Thickenededges or dowels are not necessary where new pavement will abut areas of curb and gutter, parkingstructures or other structures preventing through-vehicle traffic and associated traffic loads.

The concrete sections may be placed directly over a compacted subgrade prepared as described above.The concrete to be utilized for the concrete pavement should have a minimum modulus of rupture of550 pounds per square inch (psi). This approximates a 28-day compressive strength of 3,500 psi.However, the design strength should be based upon the modulus of rupture and not the compressivestrength. Contraction join ts should be sawcut in the pavement at a maximum spacing of 30 timesthe thickness of the slab, up to a maximum of 15 feet. Sawcutting in the pavement should be performed within 12 hours of concrete placement, preferably sooner. Sawcut depths should be equal toapproximately one-quarter of the slab thickness for conventional saws or 1 inch when early-entrysaws are utilized on slabs 9 inches thick or less. The use of plastic strips for formation of ointing isnot recommended. The use of expansion joints is not recommended, except where the pavementwill adjoin structures. Construction joints should be constructed such that adjacent sections butt


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exposed. CHJ Consultants does not practice traffic engineering. We recommend that the ADTITis used for this project be reviewed by the project civil engineer or traffic engineer to verify thatthey are appropriate for this project.

SHALLOW FOUNDATION RECOMMENDATIONS

The proposed parking structure may be supported by shallow foundations, including conventionalspread footings and grade beams, provided the recommendations contained in this report areimplemented during planning, grading and construction.

PREPARATION OF FOOTING AREAS:All footings should rest entirely upon at least 36 inches of properly compacted fill material. Themandatory removal and replacement of the upper 8 feet of existing soil will accommodate footings asdeep as 5 feet below existing grade. Additional removal and replacement will be required forfootings deeper than 5 feet. This subexcavation operation should include removal of allundocumented fill and loose upper native soils existing within the areas to be graded, even thoughplanned filling will be sufficient to satisfy compacted fill thickness requirements.

FOUNDATION DESIGN:If the site is prepared as recommended, the proposed structure may be safely founded on conventional spread foundations, either individual spread footings and/or continuous wall footings, bearingon a minimum of 36 inches ofproperly compacted soil. Footings should be a minimum of 24 incheswide and should be established at a minimum depth of 24 inches below lowest adjacent fmal


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of 1,000 tons per square foot (tsf) was also assumed for recompacted fill. These parameters shouldbe confirmed during grading.

The allowable net bearing pressures are based on a factor of safety of 3 against shear failure or anallowable settlement of 112 inch, whichever is less. The allowable bearing pressures are net values.Ifneeded, 380 ps f can be added to the net values to obtain total allowable bearing pressure.

These bearing values may be increased by one-third for wind or seismic loading.

For footings thus designed and constructed, we would anticipate a maximum static settlement of112 inch or less. Differential settlement between similarly loaded adjacent footings is expected to beapproximately one-half the total settlement. These settlement estimates do not include seismicallyinduced settlement.

With the recommended 8 feet of removal and recompaction, and provided that measures will be takento minimize water infiltration into the underlying soils, it is our opinion that hydroconsolidationsettlement will be negligible. As such, total differential settlement (including static,hydroconsolidation and seismic) on the order of 3/4 inch over 40 feet should be considered in thedesign.

MODULUS OF SUBGRADE REACTION:We recommend that a modulus of subgrade reaction, kv, of 150 kips per cubic foot (kef) be used fordesign of reinforced concrete floor and mat foundations with widths up to 18 feet. If using the


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SLABS-ON-GRADE:


To provide adequate support, concrete slabs-on-grade should bear on a minimum of 36 inches ofcompacted soil. Concrete slabs-on-grade should be a minimum of 4 inches in thickness. The soilshould be compacted to 95 percent relative compaction. The final pad surfaces should be rolled toprovide smooth, dense surfaces.

Slabs to receive moisture-sensitive coverings should be provided with a moisture vapor retarder.We recommend that a vapor retarder be designed and constructed according to the American Concrete Institute 302.1R, Concrete Floor and Slab Construction, which addresses moisture vaporretarder construction. At a minimum, the vapor retarder should comply with ASTM E1745 andhave a nominal thickness of at least 10 mils. The vapor retarder should be properly sealed, per themanufacturer's recommendations, and protected from punctures and other damages. One inch ofsand under the vapor retarder may assist in reducing punctures.

DEEP FOUNDATION RECOMMENDATIONS

As an alternative to using shallow foundations (with the necessary removal and recompaction), theproposed structure could be supported by pile foundations. For purposes of our analyses, a concretecast-in-drilled-hole (CIDH) pile foundation was assumed in order to develop preliminary conclusionsregarding pile capacity and depth. Alternative pile foundations could include driven pre-castconcrete or steel "H" piles. Pile-type selection should be based on environmental considerations,constructability and cost. Pile driving will induce localized ground vibration and is generally muchnoisier than CIDH construction. Groundwater may be a concern during CIDH pile installation.


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ALLOWABLE AXIAL PILE CAPACITIES:


Both upward and downward allowable axial capacities were calculated (Allpile Version 7.13f) for24-, 30- and 36-inch-diameter concrete CIDH piles as a function of embedment depth.Enclosures "E-1 0" and "E-ll" show the summaries of downward and uplift pile capacities,respectively. The embedment depths shown on the capacity vs. depth charts are measured from thebottom of the pile cap, which has been assumed to be approximately 6 feet bgs. Axial capacitycalculations, including soil profile, pile data and vertical capacities, are shown in Enclosures "E-1 ","E-4" and "E-7". The soil profile was generated based on Exploratory Boring No. 3. Greater orlesser pile cap elevations should result in a corresponding decrease or increase in pile depth.

The recommended capacities apply to the total of dead plus live loads and are gross values at the pilehead. Both ultimate and allowable capacities are presented in Table 7. The design engineer shouldselect capacities according to the design method. If the "strength design" method is selected,ultimate capacities should be utilized. Alternatively, if the "working stress design" method is used,allowable capacities should be selected. The nominal resistance is provided for use in load andresistance factor design (LRFD). The design engineer should apply performance factors inaccordance with corresponding design specifications.

The maximum allowable downward capacity utilized a factor of safety of 2.0 for skin friction and 3.0for tip bearing. The maximum allowable uplift capacity utilized a factor of safety of 3.0 for skinfriction and 2.0 for pile weight. Utilizing these values, the combined dead plus live loads should belimited to the values presented in Table 7. We have also included ultimate downward capacities forpiles should calculations utilizing other factors of safety be desired. These capacities may be


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For properly installed piles, it is anticipated that a total settlement of less than 1/4 inch will berequired to mobilize allowable capacity.

LATERAL PILE ANALYSES:As part of our lateral pile capacity evaluation, we analyzed the behavior of CIDH piles embeddedinto the representative soil profiles in the proposed structure area for both free- and fixed-head conditions. In each case, base shear forces were applied at the top of the pile, which was assumed to be atthe bottom of the footing. The graphed results, showing pile deflection and force distribution andlateral load vs. head deflection or maximum moment, are included in Enclosures "E-2" and "E-3","E-5" and "E-6", and "E-8" and "E-9". Based on these results, we have estimated the allowable lateral loads as shown in Table 7, considering Section 1810.3.3.2 of the 2010 CBC.

The structural engineer should use judgment when modeling the degree of fixity. If a "semi-fixed"condition is considered, the lateral deflections should be re-estimated.

Table 7Axial and Lateral Pile Capacities

ITEMSoil Profile B-3Pile Length (ft.) 50 50 50


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ITEMSoil Profile B-3Allowable Uplift Capacity (kips) 62 84 104Ultimate*, Free Head 106 140 180Nominal, Free Head 79 105 135

I'll Allowable, Free Head 53 70 90t::Point of 0 Deflection (below pile cap, ft.) 11.5 14.6 17.3~u-; Ultimate*, Fixed Head 230 300 378

....03 Nominal, Fixed Head 172 225 283Allowable, Fixed Head 115 150 189Point of 0 Deflection (below pile cap, ft.) 15.9 19.6 23.1

*Assumes a maximum lateral deflection of 1 inch at pile head

PILE SPACING AND GROUP EFFICIENCY:


Both axial and lateral capacities recommended in the above sections are for single piles. In the caseof grouped piles, the total capacity will be subjected to pile spacing. Per the 2010 CBC, groupeffects should be considered for axial downward capacities where the center-to-center spacing is lessthan 3D and for lateral capacities where the center-to-center spacing is less than 8D, where Dis thepile diameter or width. For pile groups subjected to uplift, the allowable working uplift load for thegroup should be the lesser of:

a The proposed individual pile uplift working load times the number of piles in thegroup.


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Group Eff'ects fOr Downward Capacity o(Dril/ed Group Shafts


The individual downward capacity of each shaft in the pile group should be reduced by a groupefficiency factor 11 taken as:

11 =0.65 for a center-to-center spacing of2.5 diameters 11 =1.0 for a center-to-center spacing of4.0 diameters or more

For intermediate spacings, the value ofT) may be determined by linear interpolation.

Group Eff'ects for Lateral Capacity ofDrilled Group ShaftsFor general design of foundations composed of groups of drilled shafts, the P-multiplier, PM, valuesprovided in Table 8 are suggested.

The following publications can also be referenced for the necessary group efficiency to be consideredin the design of group piles.

AASHTO, 2010, LRFD Bridge Design Specifications, 5th Edition FHWA, 2010, Drilled Shafts: Construction Procedures and Design Methods, Publication

No. FHWA-NHI-10-016


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Table 8


Recommended P-multiplier, PM, Values for Design by Row PositionDesign P-multiplier, PM

Pile Spacing (center-to-center) 3D 4D 5D ~ 6 DLead Row 0.7 0.85 1.0 1.0Second Row 0.5 0.65 0.85 1.0Third Row and Higher 0.35 0.5 0.7 1.0

CIDH PILE INSTALLATION:The installation of the CIDH piles should be observed by the geotechnical engineer to verify the soilcondition and that the desired diameter and depth of pile are achieved. CIDH piles should be trueand plumb.

Because of the granular nature of the soils encountered and the anticipated diameter of the drilledholes, it is anticipated that caving could occur during the drilling and the construction of piles withinthe on-site soils. Appropriate precautions should therefore be taken during the construction ofpilesto reduce caving and raveling.

The drilling speed should be reduced as necessary to minimize vibration and caving of the sandymaterials. Based on the data developed during our investigation, drilling for the piles may proceed


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placed with appropriate equipment, so that the concrete is not allowed to fall freely more than 5 feetand to prevent concrete from striking the walls of the shaft, thus causing caving. All loose materialsshould be cleared from the bottom of the pile excavation. This is especially important because endbearing has been considered in determining the provided pile capacities. If casing is necessary andis utilized, then the casing should be withdrawn concurrently with the concrete placement.

Prior to concrete placement, any disturbed soils under and within the area of the grade beams or at thesides ofpile caps should be compacted to at least 95 percent relative compaction (ASTM 01557).

PRE-JOB CONFERENCE:It is imperative that no clearing and/or grading operations be performed without the presence of arepresentative of the geotechnical engineer. An on-site pre-job meeting with the owner, the contractor and the geotechnical engineer should occur prior to all grading-related operations. It should bestressed that operations undertaken at the site without the presence of the geotechnical engineer mayresult in exclusion of affected areas from the final compaction report for the project.CONSTRUCTION OBSERVATION:All grading operations, including site clearing and stripping, should be observed by a representativeof the geotechnical engineer. The geotechnical engineer's field representative will be present toprovide observation and field testing and will not provide any supervising or directing of the actualwork of the contractor, his employees or agents. Neither the presence of the geotechnical engineer'sfield representative nor the observations and testing by the geotechnical engineer shall excuse thecontractor in any way for defects discovered in his work. It is understood that the geotechnical


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LIMITATIONS


CHJ Consultants has striven to perform our services within the limits prescribed by our client and in amanner consistent with the usual thoroughness and competence of reputable geotechnical engineersand engineering geologists practicing under similar circumstances. No other representation, expressor implied, and no warranty or guarantee is included or intended by virtue of the services performedor reports, opinion, documents, or otherwise supplied.

This report reflects the testing conducted on the site as the site existed during the investigation, whichis the subject of this report. However, changes in the conditions of a property can occur with thepassage of time, due to natural processes or the works of man on this or adjacent properties.Changes in applicable or appropriate standards may also occur whether as a result of legislation,application or the broadening of knowledge. Therefore, this report is indicative of only those conditions tested at the time of the subject investigation, and the findings of this report may be invalidatedfully or partially by changes outside of the control ofCHJ Consultants. This report is therefore subject to review and should not be relied upon after a period ofone year.

The conclusions and recommendations in this report are based upon observations performed and datacollected at separate locations, and interpolation between these locations, carried out for the projectand the scope of services described. It is assumed and expected that the conditions between locations observed and/or sampled are similar to those encountered at the individual locations whereobservation and sampling was performed. However, conditions between these locations may varysignificantly. Should conditions that appear different from those described herein be encountered in


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The report and its contents resulting from this investigation are not intended or represented to besuitable for reuse on extensions or modifications of the project or for use on any other project.

CLOSURE

We appreciate this opportunity to be of service and trust this report provides the information desiredat this time. Should questions arise, please do not hesitate to contact this firm at your convenience.

Respectfully submitted,CHJ CONSULTANTS

John RomanoStaff Geologist

4 -t-.;to\3

Fred Yi, Ph.D., G.E. 2967Chief Engineer

G o o ( ) ~ - - -Allen D. Evans, G.E. 2060Vice President


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REFERENCES

American Concrete Institute, 2000, Manual ofConcrete Practice, Part 3, Table 4.3.1.


American Society of Civil Engineers (ASCE), 2006, Minimum design loads for parking structuresand other structures, ASCE standard 7-05.Andrus, D. A., Piratheepan, P., Ellis, B.S., Zhang, J., and Juang, C. H., 2004, "Comparing Liquefaction Evaluation Methods Using Penetration-VS Relationships", Soil Dynamics and EarthquakeEngineering, Volume 24, Issues 9-10, October 2004, Pages 713-721.Andrus, D. A., and Stokoe, K. H., 2000, "Liquefaction Resistance of Soils from Shear Wave Velocity", Journal of Geotechnical and Geoenvironmental Engineering, Volume 126, No. 11, Pages1015-1025.Atik, L., and Sitar, N., 2010, Seismic Earth Pressures on Cantilever Retaining Structures, Journal ofGeotechnical and Geoenvironmental Engineering, Volume 136, No. 10, October 1, 2010, Pages1324-1333.Boussinesq, J., 1885, Application des Potentiels a L'Etude de L'Equilibre et du Mouvement desSolides Elastiques, Gauthier-Villars, Paris (in French).California Department ofWater Resources, 1964, Coachella Valley Investigation, Bulletin 108.California Department of Water Resources, 2012, http://www.water.ca.gov/waterdatalibrary.California Division of Mines and Geology, 1974, State of California Special Studies Zones Map,Indio Quadrangle, Official Map, dated July 1, 1974.California Division of Mines and Geology, 2008, Guidelines for evaluating and mitigating seismichazards in California: California Division ofMines and Geology Special Publication 117.Catchings, R.D., Rymer, M.J., Goldman, M.R., and Gandhok, G., 2009, Bulletin of the SeismologicalSociety ofAmerica, v. 99, no. 4, pp.-2190-2207.


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REFERENCES


Coachella Valley Water District, 2010, Coachella Valley Water Management Plan 2010 Update -Draft Report, dated December 2010.Coduto, D.P., Yeung, M. R., and Kitch, W. A., 2010, Geotechnical Engineering Principles and Practices, 2nd Edition, Pearson Higher Education, Inc., New Jersey.Dibblee, T.W., Jr., 2008, Geologic map of the Palm Desert & Coachella 15-rninute quadrangles,Riverside County, California, Dibblee Foundation Map DF-373.Dickinson, W. R., 1996, Kinematics of transrotational tectonism in the California Transverse Rangesand its contribution to cumulative slip along the San Andreas transform fault system: GeologicalSociety ofAmerica Special Paper 305.Epi Software, 2000, Epicenter Plotting Program.Federal Emergency Management Agency (FEMA), 2008, FIRM Map Panel No. 06065C2253G datedAugust 28, 2008.Fialko, Y., 2006, Interseisrnic strain accumulation and the earthquake potential on the southern SanAndreas fault system, Nature, 441, 968-971.

Fife, D.L., Rodgers, D.A., Chase, G.W., Chapman, R.H., and Sprotte, E.C., 1976, Geologic hazardsin southwestern San Bernardino County, California: California Division of Mines and GeologySpecial Report 113.Fumal, T.E., Pezzopane, S.K., Weldon, R.J., and Schwartz, D.P., 1993, A 100-year average recurrence interval for the San Andreas fault at Wrightwood, California: Science, v. 259, p. 199-203.Ikehara, M.E., Predmore, S.K., and Swope, D.J., 1997, Geodetic network to evaluate historicalelevation changes and to monitor land subsidence in Lower Coachella Valley, California, 1996: U.S.Geological Survey Water-Resources Investigations Report 97-4237.ldriss, I. M., and Boulanger, R. W., 2008, "Soil Liquefaction During Earthquake", EarthquakeEngineering Research Institute, EERI Publication MN0-12.


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Riverside County Land Information System, 2012,http://www3.tlma.co.riverside.caus/pa/rclis/index.html, accessed March 26, 2013.Robertson, P. K., and Wride, C. E., 1998, "Evaluating cyclic liquefaction potential using the conepenetration test", Canadian Geotechnical Journal, 35: 442-459.Robertson, P.K., 2009, "Interpretation of Cone Penetration Tests- a unified approach", CanadianGeotechnical Journal, Volwne 46. pp. 1337-1355.Rogers, T.H., 1965, Geologic Map of California- Santa Ana sheet, California Division of Mines andGeology.Seed, H. B., and Idriss, I. M., 1982, Ground motions and soil liquefaction during earthquakes:Earthquake Engineering Research Institute, Monograph Series, Monograph No.5.Seed, H. B., and Silver, M. L., 1972, "Settlement of dry sands during earthquakes," J. Soil. Mechanics and Foundations Div., ASCE, 98 (4), Pages 381-397.Seed, H. B., Tokimatsu, K., Harder, L. F., and Chung, R. M., 1985, Influence of SPT procedures insoil liquefaction resistance evaluations: Journal of Geotechnical Engineering, ASCE, Volume III,No.12.Silver, M. L., and Seed, H. B., 1971 Volume changes in sand during cyclic loading, J. Soil Mechanicsand Foundations Div., ASCE 97(SM9), Pages 1171-182.Sneed, M., 2010, Measurement of Land Subsidence Using Interferometry, Coachella Valley,California, Proceedings ofEISOLS 2010, Queretaro, Mexico, 17-22 October 2010, IAHS Publ. 339,2010.Sneed, M., and Brandt, J., 2007, Detection and Measurement of Land Subsidence Using GlobalPositioning System Surveying and Interferometric Synthetic Aperture Radar, Coachella Valley,California, 199fr2005, United States Geological Survey Scientific Investigations Report 2007- 5251.Sneed, M., Ikehara, M. E., Galloway, D. L., and Amelung, F., 2001, "Detection and measurement ofland subsidence using global positioning system and interferometric synthetic aperture radar,Coachella Valley, California, 1966-98," U.S. Geological Survey Water-Resources Investigations


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Treiman, J., Jerome, compiler, 1999, Fault number 124, Brawley Seismic Zone, in Quaternary faultand fold database of the United States: U.S. Geological Survey website,http://earthquakes.usgs.gov/regionallqfaults, accessed 10/05/2012.Working Group on California Earthquake Probabilities, 1988, Probabilities of large earthquakesoccurring in California on the San Andreas fault: U.S. Geological Survey Open-File Report 88-398.Working Group on California Earthquake Probabilities, 1995, Seismic hazards in southern California:Probable earthquakes, 1994 to 2024: Bulletin of the Seismological Society of America, Volume 85,No.2, Pages 379-439.Yi, F., 2013, "GeoSuite 2008, version 2.2 - A Comprehensive Package for Geotechnical and CivilEngineers", GeoAdvanced.Yi, F., 2010a, "Case Studies of CPT Interpretation and the Application in Seismic Settlement Evaluation", The 2nd International Symposium on Cone Penetration Testing, Huntington Beach, California,May 9-11,2010.Yi, F., 2010b, "Procedure to Evaluate Seismic Settlement Based on Shear Wave Velocity- Part I,Saturated Sands", The 9th U.S. National and lOth Canadian Conference on Earthquake Engineering(9USN/10CCEE), Toronto, Canada, July 25-29, 2010.Yi, F., 2010c, "Procedure to Evaluate Seismic Settlement Based on Shear Wave Velocity- Part II,Unsaturated Sands", The 9th U.S. National and lOth Canadian Conference on Earthquake Engineering (9USN/10CCEE), Toronto, Canada, July 25-29,2010.Yoshimine, M., Nishizaki, H., Amano, K., and Hosono, Y., 2006, Flow deformation of liquefied sandunder constant shear load and its application to analysis of flow slide in infinite slope, Soil Dynamicsand Earthquake Eng. 26, Pages 253-264.Youd, T. L., and Idriss, I. M., 2001, "Liquefaction Resistance of Soil: Summary Report from the1996 NCEER and 1998 NCEERINSF Workshops on Evaluation of Liquefaction Resistance of Soils",Journal ofGeotechnical and Geoenvironmental Engineering, Volume 127, No. 10.Yucca Valley, Town of, 1995, General Plan.


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AERIAL PHOTOGRAPHS REVIEWED


Riverside County Flood Control and Water Conservation District, June 20, 1974, black and whiteaerial photograph nos. 635 and 636.Riverside County Flood Control and Water Conservation District, April 15, 1980, black and whiteaerial photograph no. 669.Riverside County Flood Control and Water Conservation District, January 20, 1984, black and whiteaerial photograph nos. 865 and 866.Google Earth, 2012, imagery dated September 25, 1996; May 5, 2002; November 16, 2004;November 16, 2006; June 5, 2009; and September 16, 2011.


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APPENDIX "A"

GEOTECHNICAL MAPS


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APPENDIX "B"

EXPLORATORY LOGS

Enclosure "B" (1 of 3)


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Enclosure B (1 of 3)

Job No. 13143

Appendix E1 - Geotech Site B 4-1-13.pdf

Documents

Transcript of Appendix E1 - Geotech Site B 4-1-13.pdf