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BRES2014-1143 Geotechnical Update Reporty. Sladden En ineerin { 45090 Golf Center Parkway, Suite F, Indio, CA 92201 (760) 863-0713 Fax (760) 863-0727 6782 Stanton Avenue, Suite C, Buena Park, CA 90621 (714) 523-0952 Fax (714) 523-1369 ` 450 Egan Avenue, Beaumont, CA 92223 (951) 845-7743 Fax (951) 845-8863 _ 800 E. Florida Avenue, Hemet, CA 92543 (951) 766-8777 Fax (951) 766-8778 _ February 6, 2015 y Project No. 522-14201 M ; _ 15-02-060 Ms. Jaclin C. Smith 302 East Wedgewood - Spokane, Washington 99208 Project: Proposed Smith Residence - 80871 Vista Lazo — Lot 10 Lions Gate Development , w • La Quinta, California Subject: Report of Observations,arid Testing During Building Pad Grading Ref: 'Geotechnical Update prepared by Sladden Engineering dated August 12, 2014; Project No. 544-14201, Report No.14-08-305 This report provides a summary of our field observations along with the results of in -place `density testing performed at the subject site during the rough grading of the building pad for the proposed custom residence. The project site is located at 80871 Vista Lazo within the Lions Gate residential development in the CityofLa Quinta, California. During rough grading over -excavation and/or re -compaction was performed throughout the building pad area. Over -excavation extended to a minimum depth of 5 feet below existing grade or 3 feet below the bottom of the footings, whichever was deeper. The exposed native soil was moisture conditioned to near optimum moisture content and compacted to at least 90 percent relative compaction prior to fill placement. The previously removed soil was replaced in thin lifts at near optimum moisture content and compacted to at least 90 percent of maximum density. Field testing was performed from January 26, 2015 through February 6, 2015. Testing indicates that a minimum of 90 percent relative compaction was attained in the areas tested. The passing' test results- indicate compliance with the geotechnical report at the tested locations and depths but are no guarantee or warranty of the contractor's work.: Field Testing: In -place moisture/density tests were performed using a nuclear density gauge in accordance with ASTM Test Method D 6938-08. A total of 40 field density. tests were performed. Test results are summarized on the attached data,- sheet. The approximate test locations are indicated on the attached plan. ' �. R FEB 12 2015 y . CITY OF LA QUINTA ` - COMMUNITY DEVELOPMENT f ' February 6, 2015 -2-, Project No. 522-14201 x 15-02-060 Laboratory Testing: The moisture -density relationships for the tested materials were determined in the laboratory in accordance with ASTM Test Method D 1557-91. The proposed custom residence maybe supported upon conventional shallow foundations. Load bearing walls may be supported on continuous spread footings and interior columns may be supported on isolated pad footings. All footings should be founded upon properly engineered fill and should have a minimum embedment depth of 12 inches measured from the lowest adjacent finished grade. Continuous and isolated footings should have minimum widths of 12 inches and 24 inches, respectively. Continuous and isolated footings may be designed using allowable (net) bearing pressures of 1800 and 2000 pounds per square foot (psf), respectively. Allowable increases of 250 psf for each additional 1 foot in width and 250 psf for each additional 6 inches in depth may be utilized, if desired. The maximum allowable bearing pressure should be 2500 psf. The allowable bearing pressures apply to combined dead and sustained live loads. The allowable bearing pressure may be increased- by'one-third when considering transient live loads, including seismic and wind forces. All footings should be reinforced in accordance with the project structural engineer's recommendations. If there are any, questions regarding this report or the testing summarized herein, please contact the undersigned. Respectfully submitted - SLADDEN ENGINEERING "M SS/O�,�l M BRETf L. , Brett Anderson DERSON " + No. 89 IT' Principal Engineer Exp. 9/3on iii CIVIL �t ENGINEERING Grading/gvm �TFOF CA1�F�� -Copies 4 / Ms. Jaclin C. Smith • , a r • J, Sladden Engineering ProjectRame: Custom Residencei TEST RESULTS I Location: 80871 Vista Lazo, La .Quinta, California, - PROJECT NO: 522-14201 REPORT NO: 15-02-060 Test No Date Tested `Location Elevation ry vensity in place Yo moisture in place Relative Compaction Maximum Density Building Pad 1 01/26/15 Per Plan 454.5 111.2 14.6 98 114.0 2 01/27/15 Per Plan . 456.0 109.3 15.5 96 114.0 3 01/27/15' Per Plan. 456.5 112.6 13.1 99 114.0 4 01/28/15 Per Plan 458.0' 107.6 16.5 94 114.0 5 01/28/15 'Per Plan 459.0 103.1 17.0 90 114.0 6 01/29/15 Per Plan 455.0 103.5 ' 15.1 91 114.0 7 - 01/29/15 Per Plan 457.0 108.6 13.9 95 114.0 8 01/30/15 Per Plan y 457.0 107-.1 17.0 . 94 114.0 9 01/30/15 Per Plan 456.5 - 104.6 16.3 92 114.0 10 01/30/15 Per Plan 455.0 102.8 16.1 90 114.0 11 01/30/15 Per Plan l 454.5 102.7 15.9 90 114.0 12 01/30/15 Per Plan 456.0 , 103.5 17.3 91 114.0 13 02/02/15 Per Plan 457.5 104.1 12.6 92 113.0 14 02/02/15 Per Plan' _- 457.5 103.7 .13.9 92 113.0 15 02/02/15 Per Plan 459.0 ' 103.4 12.4 92 113.0 16 02/02/15 Per Plan .-459.0 103.0 14.5 91 113.0 17 02/02/15 - Per Plan 457.5 106.6 12.1 94 113.0 18 02/02/15 Per Plan 457.5• 110.3 12.5 98 113.0 19 02/02/15 Per Plan " 459.0 103.6 12.2 • 92 113.0 20 02/02/15 Per Plan . 459.0 107.1 13.0 95 113.0 21 02/02/15 Per Plan '.= 459.0 107.6 12.3 95 113.0 22 02/02/15 Per Plan ':M 455.5 102.0 12.7 90 113.0 23 02/02/15 Per Plan'. 455.5 102.5 13.0 91 113.0 24 02/02/15' Per Plan 459.6 102.2 11.7, 90 113.0 25 02/02/15 Per Plan 459.0 1016 12.1 92 113.0 26 02/02/15 Per Plan " 459.0 102.0 11.8 90 113.0 27 02/02/15 Per Plan # 457.5 103.0 12.2 91 113.0 28 02/02/15 Per Plan 457.5 102.9 11.9 91 113.0 29 02/02/15 Per. Plan 457.5 , 104.8 12.8 93, 113.0 30 02/03/15 Per Plan 459.0 - 102.6 13.4 91 113.0 31 02/03/15 - Per Plan. 459.0. 104.8 11.6 93 . 113.0 32 02/03/15 Per Plan 459.0 102.0 12.1 90 113.0 33 02/03/15 Per Plan ` - 459.0 -'101.8, 11.9. 90 113.0 34 02/06/15 Per Plan 459.5 • 109.6 11.6 97 '113.0 35 02/06/15 Per Plan 459.5' • 1071 13.1 95 113.0 36 02/06/15 Per Plan` 459.5' 110.2 1-2.7 98 113.0 37 02/06/15 Per Plan 459.5 106.5 11.5 94. 113.0 38 02/06/15 Per Plan , - 459.5 109.4 11.9 97 113.0 39 02/06/15 - Per Plan • .. 459.5 ' :. 102.9 11.4-' 91 .. 113.0 40 1 02/06/151 Per Plan 459.5 104.3 12.9 92 113.0 February 6, 2015 `{<, r 1 '; Sladden Engineering it EXIST. FF=(460.47) EXIST. RESIDENCE iz KIM AG NIZ 41 01 VA T ID Naw ji SMITH RESIDENCE PRECISE GRADING P,LAN Sladden Engineering 45090 Golf Center Parkway, Suite F, Indio, CA 92201(760) 663-0713 Fax (760) 863-0847 j 6782 Stanton Avenue, Suite A, Buena Park, CA 90621 (714) 523-0952 Fax (714) 523-1369 450 Egan Avenue, Beaumont, CA 92223 (951) 845-7743. Fax (951) 845-8863 800 E. Florida Avenue, Hemet, CA 92543 (951).766-8777 Fax (951) 766-8778 August 12, 2014 Project No. 544-14901 14-08-305 Ms. Jaclin C.-Smith 302 East Wedgewood Spokane, Washington 99208 Project: Proposed Smith Residence Vista Lazo —Lot 10 Lions Gate Development La Quinta, California Subject: Geotechnical Update Ref: Geotechnical Engineering: Report prepared by Earth Systems Consultants dated January 1.1, 1995; File No. SS-5234-PI, Report No. 94-12-718 Geotechnical Investigation prepared by Sladden Engineering dated December 1, 2010; Project No. 544=10198, Report No: 1.0-12-279 As requested, we have reviewed the above referenced geotechnical reports as they relate to the design and construction of the proposed custom residence. The project site is located on Vista Lazo (identified as Lot 10) within the Lions Gate development in the City of La Quinta, California. It is our understanding that the proposed residence will be a relatively lightweight wood -frame structure supported by conventional shallow spread footings and concrete stabs' on grade. The referenced reports include recommendations pertaining to the construction of residential structure foundations. In addition, the., Geotechnical Investigation prepared by Sladden Engineering in 2010 addresses potential' seismic hazards, hydro -collapse, seismic settlement and subsidence potential in accordance.with the City of La Quinta geotechnical guidelines. Based upon our review it is our opinion that the recommendations provided in the referenced reports remain applicable for the design and construction of the proposed residential structure foundations. In order to provide for firm and uniform foundation support, we recommend over -excavation and recompaction of the artificial fill -soil and the primary foundation bearing soil. The building areas should be cleared of surface, vegetation prior to grading. The surface soil should be over - excavated to a depth of 51eet below existing grade or 3 feet below the bottom of the footings, �® whichever is deeper. The exposed surface should be scarified, moisture conditioned and o 04 compacted to a minimum of '90 percent relative compaction prior to fill placement. The r `" ccy a previously removed soil and fill material should be placed in thin lifts at near optimum moisture content and compacted to at least 90 percent relative compaction. F— CD Sladden Engineering August 12, 2014 -2- Project No. 544-14201 14-08 30 Based upon our review, it is our opinion that the proposed custom residence may be supported upon conventional shallow foundations. Load bearing walls may be supported on, continuous spread footings and interior columns may be supported on isolated pad footings. All footings should be founded upon properly engineered fill and should have a minimum embedment depth of 12 inches measured from the lowest adjacent finished grade. Continuous and isolated footings should have a minimum width of 12 inches and 24 inches respectively. Continuous and isolated footings placed on such materials may be designed using an allowable (net) bearing pressure of 1.800 and 2000 pounds per square foot (psf) respectively. Allowable increases of 250 psf for each additional I foot in width and 250 psf for each additional 6 inches in depth may be utilized, if desired. The maximum allowable bearing pressure should be 2500 psf. The maximum. bearing. pressure applies to combined dead and sustained live loads. The allowable bearingpressure may be increased by one-third when considering transient live loads, including seismic and wind forces. All footings should be reinforced in accordance with the project structural engineer's recommendations. Based on the allowable bearing pressures recommended above, total settlement of the shallow footings are anticipated to be less than one -inch, provided foundation preparations conform to the recommendations described in this report. Differential settlement is anticipated to be approximatelyhalf the total settlement for similarly loaded footings spaced up to approximately 40 feet apart. Lateral load resistance for the spread footings will be developed by passive soils pressure against the sides of the footings below grade and by friction acting at the base of the concrete footings bearing on compacted fill. An allowable passive pressure of 300 psf per foot of depth may be used for design purposes. An allowable coefficient of friction 0.45 may be. used for dead and sustained live loads to compute. the 'frictional resistance of the footing placed directly on compacted fill. Under seismic and wind loading conditions, the passive pressure and frictional resistance may be increased by one-third. The bearing soil is non -expansive and falls within the "very low" expansion category in accordance with 2013 California Building Code (CBC) classification criteria. Slab tickness and reinforcement should be determined by the, structural engineer. We recommend a minimum floor slab thickness of 4.0 inches and minimum reinforcement of #3 bars approximately 18 inches on center in each direction. All slab reinforcement should be supported on concrete chairs to ensure that reinforcement is placed at slab mid -height. Slabs with moisture sensitive surfaces should be underlain with a moisture vapor retarder consisting of a polyvinyl chloride membrane such as 10-mil Visqueen, or equivalent. All laps within the membrane should be sealed aind at least 2 inches of clean sand should be placed over the membrane to promote uniform curing of the concrete. To reduce the potential for punctures, the membrane should be placed on a pad surface that has been graded smooth without any sharp protrusions. If a-smoothsurface can not be achieved by grading, consideration should be given to placing a 1-inch thick leveling course of. sand across the "pad surface prior to placement of the membrane. Sladifen Engineering August 12, 2014 -3- Project No. 544-1.4201. 14-08-305 Based.on our field observations and understanding of local geologic conditions, the soil profile type judged applicable to this site is So, generally described as stiff soil. The following presents additional coefficients and factors relevant to seismic mitigation for new construction based upon the 2013 California Building Code (CBC). The seismic design category for a structure may be determined in accordance with Section I.613 of the 2013 CBC or ASCE7. According•to the 2013 CBC; Site Class D may be used to estimate design seismic loading for the proposed structures. The 2013 CBC Seismic Design Parameters are summarized below. Risk Category (Table 1.5-1): I/11/111 Site Class (Table 1613.3.2): D: Ss (Figure 1613.3.1): 1.500g' S1 (Figure 1613.3.1):'0.608g Fa (Table 1613.3.3(1)):1.0 Fv (Table 1613.5.3(2)): 1.5 Sms (Equation 16-37 {Fa X Ss)): 1.500g Sml (Equation 16-38 )Fv X Si)): 0.912g . SDS (Equation 16-39 )2/3 X Sms)): 1.000g SD1 (Equation 16-40 (2/3 X Sm1)): 0.608g Seismic Design Category: D In addition, we have sampled the surface soil on.the subject lot to determine the soluble sulfate content as it relates to selecting appropriate concrete mix designs. Testing indicates that the site soil is generally considered non- corrosive with respect to concrete. The testing indicated soluble sulfate content of 400 ppm (0.040 percent) that corresponds with the "negligible" exposure category in accordance with ACI 318-08, Table 3.' Based upon tips, the use of sulfate resistance concrete mixes is not required. If you have questions regarding this ,letter or the referenced reports, "please contact the undersigned. Respectfully submitted, SLADDEN ENGINEERI fESSlp� Brett L. Anderso NDER -, Z Principal Engineer NO. C45389 c p 9�so1a4 m s CNIL SER/gvm �, i�ao Copies: 4 / Addressee ShUlden Engineering .LA QUINTA: Please verify that soils reports contain all of the above -information, In addition, to assure continuity between'the investigation/reporting stage and the execution stage, please use the following checklist to verify that.the conclusions and recommendations in the report cover all the required'eiements. Only then. can we be assured that the constructlon documents address all of the site, soil conditions. La Quinta Geotechnical Report Checklist Does the "Conclusions and Recommendations" section of the report address each of the following criteria? "Address" means: (a) the criterion is considered significant and mitigation rneasure(s)_noted, or; 4 (b) the criterion is considered insignificant and explicitly,so stated. Ys No Criterion D Foundation criteria .based. upon bearing capacity of natural or compacted soil. ® Foundation criteria to.mitigate the effects7of expansive soils. , ® Foundation criteria based upon bearing capacity of natural er compacted soil. ® Foundation criteria to' mitigate the effects of liquefaction: Foundation criteria" to mitigate the effects of seismically induced differential .settlement.Ile ® foundation criteria to mitigate the effects of long-term differential settlement. ®' Fouridatiori criteria to mitigate the effects of'- ng soil strength. Foundation'critena to mitigate expected total and differential settlement. Any "No' "' answers to the -above checklist' should be noted as specific required, cosRr-TT L. F } _ # � Yt .. ! `,r ANDERSON N0. 12 09114 m IT. r t±j `�. CIVERING MAXIMUMM •. HORfAAL'-WEIdWANO - WATER-CEME[1'[TTIOUS UG�EIGHT. MATERIALS-'RATIOiBY.-: AGGREGATE•CORCRETF EXPOSURE CONDfT10N -WE)GNT,.7NOR MAL•WEIGHT AGGREGATE CONCRETE :_::;Fsl.: x n.ma9-for MPa Concrete intended to have low permeability when exposed to water 0.50 4,600 , Concrele exposed to'frcczing and thawing in a moist' condition or to deicing chemicals 0.45 4 500 For corrosion protection for reinforced concrete exposed to chlorides from deicing chemicals, salts or . brackish water, orspray-from thesc'sources 0.40 5,000 TABLE 19-A-3—REQUIREMENTS:FOR CONCRETE _ r EXPOSED TO SULFATE -CONTAINING SOLUTIONS - i • s •. NORMAL -WEIGHT LIGHTWEIGHT :AGGREGATE AGGREGATE CONCRETE Mwdmum;Watar. •Mdtedala'Rotio;by:. f^,Normal- • WATER- SOLUBLE •• Camentlllous ' olpht•and SULFATE rr50���IHSOI �PERCENTAGEBY •+' -r_ ' - Wdggby .HCFMGM.tgtit- -',1JghtwelphI' -AOB!'a0ale,. SULFATE SULFATE (SOS) IN " Concrata; pslt EXPOSURE WEIGHT , WATER, ppm CEMENT TYPE AOnro9ale Concratel x G.DD6a4'forMPa Negligible 0.00-0.10. _ '. 0-150 Modcratcz• 0.IM-20 _ 150-1,500 U. EP(MS), is '0-50. 4.WG Severe 0.20-2-00 1,500-1.0,000 V 0.49 4,500 Very severe Over 2.00 Over 10,000 V plus 0.45 4,500 pozzola13 - IA lo*W W2ter-CCM-1iti ous matena s rauo orht higher 1 $th may belcyuired for low pame56i1ityor forproteetian agains t corrosion 'of embedded items or freezing and thawing (]able L9=A z Seawater. - ?Pozzolan thathas been determined by trst or service ¢card tairiing "Typo V ccunem [o improve sulfate rr istanct'whcn used inconcrcte eon- 2-264 i 1 la den Engineering 45000 Golf Center Parkway, Suite F, Indio, California 92201 (760) 863-0713 Fax (760) 863-0847 6782 Stanton Avenue, Suite A, Buena Park, CA 90621 (714) 523-0952 Fax (714).523-1369 450 Egan Avenue, Beaumont, CA 92223 (951) 845-7743 Fax (951) 845-8863 ' . 800 E. Florida Avenue, Hemet, CA 92543 (951) 766-8777 Fax (951) 766-8778 December 1, 26.0 ;Project No. 544-10198 10-12-279 Sunbird Investments, Ltd. J C/o Steven de Christopher 42575 Melanie Place, Suite C Palm Desert, California 92211 ' :" ' ` Subject: Geotechnical Investigation a Project Proposed Ptammond Resid_ once " -• - 80-810 Vista Lazo Lion's Gate r La Quinta, California ` Sladden Engineering is pleased to present the results of our geotechnical investigation for the proposed custom residence to be. constructed witizin The Lion's Gate residential development in the City of La Quinta, California. Our services were completed in accordance with our proposal for geotechnical engineering services dated November 8, 2010 and your authorization to proceed with the work. The purpose of our investigation was to_explore''the subsurface conditions at the site in order to provide recommendations'for foundation design •and site preparation. Evaluation of environmental issues and hazardous wastes was not included within the scope of services provided. The opinions, recommendations and de's_ign criteria presented in this report are based on our field exploration program, laboratory'testing 'and -engineering an Based on . the results of our investigation, it is our professional •opinion that the, proposed project is feasible provided the recommendations presented in this report'are implemented in the design and carried out through construction. We appreciate the opportunity to provide service to you on this project. If you have any questions regarding this report,' please contact the undersigned: FESS/ e�p p� Respectfully submitted, SLADDEN ENGINEERING �. �. No. C 45389 rM i' ;(® Exp. "LI-2012 "CIVIL @ Matthew J. Cohrt @6 Matthew J• 'A ' ' .,Brett L. nderso FOF CALF , - A Project Geologist" a Cohrt © Principal ..Engineer No.8567 � , SER/mc ®C��e� Copies: 6/Addressee • N _ _ Sladden Engineering . is �r� •. - . � + h � • y � ', . • ' GEOTECHNICAL INVESTIGATION PROPOSED HAMMOND RESIDENCE �` 80810 VISTA LAZO . ' + y+ LION'S GATE LA'QUINTA, CALIFORNIA t ' r f December 1,,2010 ' TABLE OF CONTENTS ,_ t INTRODUCTION .. .... 1 PROJECT DESCRIPTION ............... ... .:..... ........ 1 . SCOPEOF SERVICES .................... ......... A �...................................................................................... 2 -' SITE CONDITIONS............ - ....... ............................. GEOLOGIC SETTING ...................................... ................................................................... 3 . .......... ... SUBSURFACE CONDITIONS-.........:'......:. ,.............. :. ......:: ::...............3 SEISMICITY AND FAULTING ' CBC DESIGN PARAMETERS....... _ - .............................. 5 s GEOLOGIC HAZARDS. .......................... :......... 5 CONCLUSIONS ................................... '' .... 1 ..4 ........ 7 .... EARTHWORK AND GRADING .. s Stripping .................................. :.. 8 " 4 i Preparation of Building Areas ;.... :...................... 8 Compaction..... ............................................................8 Shrinkage and Subsidence ....... '...................... 9 ..... ............... FOUNDATIONS SPREAD FOOTINGS ... ' SLABS-ON-GP.ADE ....................... .... ' .... ' 10 _ SOLUBLE SULFATES ..............:...... .............. ............ ......... .......................................-..-......10 .r UTILITY TRENCH BACKFILL ......................................................................... ......'.:..:: ...::.................10 EXTERIOR CONCRETE FLATWORK :..:�............ A,- ' ............•} DRAINAGE................................11 LIMITATIONS .............................. ' :.:....:..:.. 11 ..... ... .,.. . ... ... ADDITIONAL SERVICES. ...... :... ......:.. ..... .12 REFERENCES - l'.... t ... . '.............................................'....13 FIGURES - . f Site Location Map, Regional Geologic Map - Borehole Location Plan APPENDIX A - Field Exploration';,,. APPENDIX B • Laborato�.y Testing �• • `r r ~.: ' Sladden Engineering r December 1, 2010 7, _ Project No. 544-10198 10-12-279 INTRODUCTION This' report presents the results of the geotechnical investigation performed by Sladden Engineering (Sladden) for the proposed custom residence to be constructed at 80-810 Vista Lazo within The Lion's Gate development in the City of La Quinta, California. The site is located within the SE 114 of. Section 21, Township 6 South, Range 7 East (SBBM) at approximately 33.628480 north latitude and 116.252680 west longitude. The approximate location of the site is indicated on the Site1ocation Map (Figure 1). Our investigation was conducted in order to evaluate the engineering properties of the subsurface materials, to evaluate their in -situ _ characteristics, and to provide engineering recommendations and design criteria for site preparation, foundation design and the design of.various site improvements. This study also includes a review of published and unpublished geotechnical and geological literature regarding seismicity at and near the subject site. PROJECT DESCRIPTION Based on our preliminary conversations, it is our understanding that the proposed project will consist of constructing a new custom residence on the lot. Sladden anticipates that the proposed project will also include new swimming pool, exterior concrete flatwork and associatedsite improvements. For our analyses we expect that the proposed residence will consist of a relatively lightweight one or two-story, wood -frame structure supported on conventional- shallow spread footings and concrete slabs -on -grade. Grading plans and finished floor -elevation were not available at the time of this report. however, based on the previous rough grading conductedat the site, we expect that grading will be limited to minor cuts and fills in order to accomplish the desired pad elevations and provide adequate gradients for site drainage. We recommend removal and recompaction of the primary foundation bearing soil in order to provide uniform foundation support. Upon completion of precise grading plans, Sladden should be retained in order to ensure that the recommendations presented within in this report are incorporated into the design of the proposed project. Structural foundation loads were not available at the time of this report. Based on our experience with relatively lightweight structures, we expect that isolated column loads will be less than 30 kips and continuous wall loads will, be less than 3.0 kips per Iinear foot. If these assumed loads vary significantly from the actual loads, we should be' consulted to verify the applicability of the recommendations provided. Sladden Engineering `T December 1, 2010 -2- Project No. 544-10198 r 10-12-279 SCOPE OF SERVICES The purpose of our investigation was to determine specific engineering characteristics of the surface and near surface soil, in order to develop foundation design criteria and recommendations for site preparation. Exploration of the site was achieved -by drilling two (2) exploratory boreholes to depths of approximately 21.5 and 51.5 feet below (existing) ground surface (bgs)-. Specifically, our' site characterization consisted of the following tasks: Site reconnaissance to assess the existing surface conditions on and adjacent to the site. Advancing two (2) exploratory boreholes to depths of approximately 21.5 and 51.5 feet bgs in order to characterize the subsurface soil conditions. Representative samples of the soil were classified in the field and retained for laboratory testing and engineering analyses. Performing laboratory testing on selected samples to evaluate their engineering characteristics. ® Reviewing geologic literature and discussing geologic hazards. o Performing engineering analyses to develop recommendations for foundation design and site preparation. The preparation of this report summarizing our work at die site. SITE CONDITIONS The site is located at 80-810 Vista Lazo within the Lion's Gate development in the City of La Quinta, California. The undeveloped lot is formally identified as APN: 762-250-021 and occupies approximately 0.51 acres. The proposed building area was previously rough graded. As such, previous grading has created a relatively flat building area. -The site is bounded by vacant land to the north and west, and Vista Lazo to the immediate east and south. At the time of our investigation, the site was undeveloped: Based on our review of the USGS (198,0), .the site is situated at an `approximate elevation of 40 feet below mean sea level (MSL). No natural ponding of water or surface seeps were observed at or near the site during our investigation conducted on November 18, 2010. Site drainage appears to be controlled via sheet flow and surface infiltration. Regional drainage is provided by the Whitewater River that is located approximately seven (7) miles northeast of the site. Sladden Engineering 0 r December 1., 2010 - 3 - Project No. 544-10198 10-12-279 GEOLOGIC SETTING The project site is located within the Colorado Desert Physiographic Province (also referred to as the Salton Trough) that is characterized as a northwest -southeast trending structural depressionextending from the Gulf of California to the Banning Pass. The Salton Trough is dominated by several northwest trending faults, most notably the San, Andreas Fault system. The Salton Trough is bounded by the Santa Rosa — San Jacinto Mountains on the southwest, the San Bernardino Mountains on the north, the Little San Bernardino - Chocolate — Orocopia Mountains on the east, and extends through the Imperial Valley into the Gulf of California on the south. A relatively thick sequence (20,000 feet) of sediment have been deposited in the Coachella Valley portion of the Salton Trough from Miocene to present times. These sediments are predominately terrestrial in nature with some lacustrian (lake) and minor marine deposits. The major contributor of these sediments has been the Colorado River: The mountains surrounding the Coachella Valley are composed primarily of Precambrian metamorphic and Mesozoic "granitic" rock. The Salton Trough is an internally. draining area .with no readily available outlet to Gulf of California and with portions well below sea level (-253' msl). The region is intermittently blocked from the Gulf of California by the damming effects of the Colorado River delta (current elevation +30'msl). Between about 300AD and 1600 AD (to 1700.?) the Salton Trough has been inundated by the River's water, forming ancient Lake Cahuilla (max. elevation +58' 1 msl). Since that time the floor of the Trough has been repeatedly flooded with other "fresh" water lakes (1849, 1861, and 1691), the most recent and historically long lived being the current Salton Sea (1905). The sole outlet -for these waters is evaporation, leaving behind vast amounts of terrestrial sediment materials and evaporite minerals. The site has been mapped by Rogers (1965) to be immediately underlain by undifferentiated Quaternary - age lake deposits and alluvium (Ql-Qal). The regional geologic setting for the site vicinity is presented on the Regional Geologic Map (Figure 2). SUBSURFACE CONDITIONS The subsurface conditions at the site were investigated by drilling two (2) exploratory boreholes to depths of 21.5 and 51.5 feet bgs in order to observe the subsurface soil conditions. The approximate locations of the boreholes are illustrated on the Borehole Location Plan (Figure 3). The boreholes were advanced using a truck -mounted Mobile B-61 drill -rig equipped with 8-inch outside diameter (O.D.) hollow stem augers. A representative of Sladdeni was on -site to log the materials encountered and retrieve samples for laboratory testing and engineering analysis. During our field investigation, artificial fill soil consisting of:-silty,sand and sandy silt (SM-ML) was encountered to an approximate maximum depth of five (5) feet bgs. Underlying the fill soil and extending to maximum depths explored, lacustrine and alluvial deposits were encountered. Generally, the underlying earth materials observed within the bores appeared adequate for the anticipated foundation loads at relatively shallow exploration depths. Detailed descriptions of the subsurface materials encountered are included in Appendix.A of this report: Sladden Engineering it ` December 1, 2010 Project No. 544-10198 10-12-279 Groundwater was not encountered to a maximum explored depth of 51.5 feet bgs during our field investigation conducted on November 18, 2010. As such, it is our opinion that groundwater should not be a factor during construction of the proposed project.: ' SEISMICITY AND FAULTING, The southwestern United States is a tectonically active and structurally complex region, dominated by northwest trending dextral faults. The faults of the region are often part of complex fault systems, composed of numerous subparallel faults which splay or step from main fault traces. Strong seismic shaking could be produced by any of these faults during the design life of the proposed project. We consider the most significant geologic hazard to the project to be the potential for moderate to strong seismic shaking that is likely to occur during the design life of the project. The proposed project 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. An active fault is defined by the State of California as a "sufficiently active and well defined fault that has exhibited surface displacement within the Holocene epoch (about the last 11,000 years). A potentially active fault is defined by the State as a fault With a history of movement within Pleistocene time (between 11,000 and 1.6 million years ago). M As previously stated, the site has been subjected to strong seismic shaking related to active faults that traverse through the region. Some of the more significant seismic events near the subject site within recent times include: M6.0 North Palm Springs (1986), M6.1 Joshua Tree (1992), M7.3 Landers (1992), M6.2 Big Bear (1992),M7.1 Hector Mine (1999) and M7.2 Baja California (2010). Table 1 lists the closest known potentially active faults that was generated in part using the EQFAULT computer program (Blake, 2000), as, modified using the fault parameters from The Revised 2002 California Probabilistic Seismic Hazard Maps (Cao et al, 2003). This table does not identify the probability of reactivation or the on -site effects from earthquakes occurring on any of the other faults in the region. TABLE 1 CLOSEST KNOWN ACTIVE FAULTS -4- Fault Name Distance, (Km) Maximum Event San Andreas - Coachella ,13.1 7.2 San Andreas - Southern I3.1 7.2 San Jacinto - Anza 28.2 7.2 San Jacinto - Coyote Creek 30.2 6.8 Burnt Mountain 37.0 6.5 Eureka Peak 38.5 _ 6.4 San Andreas - San Bernardino 38.8 7.5 Sladden Engineering e December 1, 2010 - 5 _ Project No. 544-10198 10-12-279 2007 CBC SEISMIC DESIGN PARAMETERS Sladden has reviewed the 2007 California Building Code (CBC) and summarized the current seismic design parameters for the proposed. structure. The seismic design category for a structure may be determined in accordance with Section 1613 of the 2007 CBC or ASCE7. According to the 2007 CBC, Site Class D may be used to estimate design seismic loading for the proposed structures. The period of the structures should be less than '� second. This assumption should be verified by the project structural engineer. The 2007 CBC Seismic Design Parameters are summarized below. Occupancy Category (Table 1604.5): II Site Class (Table 1613.5.5): D Ss (Figure 1613.5.1): 1.500g S1 (Figure 1613.5.1): 0.600g Fa (Table 1.613.5.3(1)):1.0 Fv (Table 1613.5.3(2)): 1.5 Sms (Equation 16-37 (Fa X Ss)): 1.500g Sml (Equation 16-38 (Fv XS1O: 0.900g SDS (Equation 16-39 12/3 X Smsj):1.00Og SDI (Equation 16-40 (2/3 X Sm1O:; 0.600g Seismic Design Category: D GEOLOGIC HAZARDS.,, The subject site is located in an active seismic zone and will likely experience strong seismic shaking during die design life of the proposed project. In general, the intensity of ground shaking will depend on several factors including: the distance to, the earthquake focus, the earthquake magnitude, the response characteristics of the underlying materials, -and the quality and type of construction. Geologic hazards and their relationship to the site are discussed below. I. Surface Rupture. Surface rupture is expected to occur along preexisting, blown active fault traces. However, surface rupture could potentially splay or step from known active faults or rupture along unidentified traces. Based on our review of Rogers (1,965), Jennings (1994), Hart and Bryant (1997), and RCL1S (2010), no known faults are currently mapped on or projecting towards the site. in addition, no signs of active surface faulting were observed during our review of non -stereo digitized photographs of the site and site vicinity (Google, 2010; Terra Server 2002).'Finally, no signs,of,active surface fault rupture or secondary seismic effects (lateral spreading; lurching etc.) were identified on -site during our field investigation. Therefore, it is our opinion that risks associated with primary surface ground rupture should be considered "low" IL' Ground Shakins. The site has been subjected to .past ground shaking by local and regional faults that traverse through the region. A- probabilistic approach was employed to the estimate the peak ground acceleration.(a.„x) that could be experienced at the site. Based on the USGS Probabilistic Hazard Curves (USES, 2009) the site could be subjected to ground motions on the order of 0.4742g. The peak ground acceleration at the site is judged to have a 475 year return period and a 10 percent chance of exceedence in 50 years. Sladden Engineering December 1, 2010 - 6 - Project No. 541-101.98 _ 1 ' - 10-12-279 ' 1II.: Al Liquefaction. Liquefaction is the process in which loose, saturated granular soil loses strength as a result of cyclic loading. The strength loss is a result of a decrease in granular sand volume and a positive increase in pore pressures. Generally, liquefaction can occur if all of the following conditions apply: liquefaction -susceptible soil, groundwater within a depth of 50 feet or less, and strong seismic shaking, According to the County of Riverside, the site is situated within a "High to Moderate" ' liquefaction potential zone (RCLIS, 2010). Based on our review of groundwater maps of the site, vicinity (>50 feet bgs; Tyley, 1975), and our experience in the project vicinity, risks . associated with liquefaction and liquefaction related hazards, should be considered negligible. t IV. Tsunamis and Seiches. Because the 'site is situated at an inland location, and is not immediately adjacent to any impounded bodies of water, risk associated with tsunamis and Seiches is considered negligible. V. Slope Failure, Landsliding, Rock Falls. The site is situated on relatively level ground and not situated adjacent to any Hillsides. Accordingly, risks associated with slope instability and rock falls hazards are considered "negligible". VI. Expansive Soil. Generally, the site soil consists of silty sand (SM). Based on the results of our laboratory testing (EI=12), the materials underlying the siie are considered to have a "very low" expansion potential and the risk of structural damage caused by volumetric changes in the subgrade soil is considered "negligible". VI1. Settlement. Settlement resulting from the'anticipated foundation loads should be tolerable provided that the recommendations included.in this report are considered in foundation design -and construction. The estimated ultimate settlement is calculated to be less that approximately one inch when using the recommended bearing values. -As a practical , matter, differential settlement -between footings can be assumed as one-half of the total settlement. . VIR. , Subsidence. The site situated:within a "Susceptible" subsidence zone (RCLIS, 2010). Land subsidence can occur in valleys where aquifer, systems have been•subjected to .'extensive' groundwater pumping, such that groundwater pumping exceeds groundwater recharge- Generally, pore water reduction can result in a rearrangement of skeletal grains and could result in elastic (recoverable) or inelastic (unrecoverable) deformation of an aquifer system. Recent published literature indicates that the Upper Coachella'Valley region between 1996 and 2005 has been subjected to groundwater withdrawal related subsidence (USGS, 2007). Although recent investigations have documented significant subsidence within the La Quinta. area (USGS, 2007), no' fissures or other. sutficial evidence of subsidence were observed _at the subject site. With the exception of isolated tension zones typically manifested on the ground surface as fissures and/or ground cracks, subsidence related to groundwater depletion is generally areal in nature with limited differential settlement over - short distances such as across individual buildings. ' V - ,. Sfadden Engineering December 1, 2010 - 7 - Project No. 544-1.01.98 10-12-279 The Coachella Valley Water" ater District has publically acknowledged regional subsidence throughout the southern portion of the Coachella Valley and has indicated a commitment to groundwater replenishment programs that are intended to limit future subsidence. At this time, subsidence is considered a regional problem requiring regional mitigation not specific to the project vicinity.. Locally, no fissures or other surficial evidence of subsidence were observed at or near the subject site. However, site specific effects resulting from long term regional subsidence is beyond the scope of our investigation. IX. Debris Flows. -Debris flows are viscous flows consisting of poorly sorted mixtures of sediment and water and are generally initiated on slopes steeper than approximately six horizontal to one vertical (6HAV)(Boggs, 2001) Because the building area is located on elevated topography risks associated with debris flows should be considered remote. X. Flooding and Erosion. No signs of flooding or erosion were observed during our field investigation conducted on November 18, 2010 Accordingly, risks associated with flooding and erosion should be considered low. CONCLUSIONS Basedon the results of our investigation, it is our, professional opinion that the project is feasible from a soil mechanic's standpoint provided the recommendations of this report are incorporated in the design and carried out through construction. The main geotechnical concern in the construction of the proposed project is the presence of potentially compressible surface soil. The surface soil is considered loose, potentially compressible and not suitable for support of shallow foundations or concrete slabs in its existing condition. Because of the somewhat loose and potentially compressible condition of the near surface soil and undocumented nature of the fill soil, remedial grading including overexcavation or recompaction is recommended for the proposed building and foundation areas. We recommend that remedial grading within the proposed building areas include overexcavation and recompaction of the primary foundation bearing soil. Specific recommendations for site preparation are presented in the Earthwork and Grading section of this report. Caving did occur to -varying degrees within. each of our exploratory bores and the surface soil may be susceptible to caving within deeper excavations. All excavations' should be constructed in accordance with the normal CalOSHA excavation criteria. On the basis of our observations of die materials encountered, we anticipate that the subsoil will conform. to that described by Ca1OSF1A as Type•B or C. Soil conditions should be verified in the field by a "Competent person" employed by the Contractor. The following recommendations present more detailed design criteria that have been developed on the basis of our field and laboratory investigation. Sladden Engineering ' December 1, 2010 - 8 - Project No. 544-10198 1.0-12-279 EARTHWORK AND GRADING All -earthwork including excavation, backfill and preparation of the subgrade soil should be performed in accordance with the geotechnical recommendations presented in this report and portions of the local regulatory requirements, as applicable. All earthwork should be performed under the observation and testing of a qualified soil engineer. The following geotechnical engineering recommendations for the proposed project are based on our field' investigation program, laboratory testing and geotechnical engineering analyses. a. Stripping. Areas to be graded should be cleared of any existing structures, vegetation, associated root systems, and debris. All areas scheduled to receive fill should be cleared of old fills and any irreducible matter. The strippings should be removed off site, or stockpiled for later use in landscape areas. Voids left by obstructions should be properly backfilled in accordance with the compaction recommendations of this report. b. Preparation of the Building Areas. In order to provide for firm and uniform foundation support, we recommend overexcavation and recompaction of the primary foundation bearing soil. The building area should be cleared of surface vegetation prior to precise grading. The surface soil should be overexcavated to a depth of 5 feet below existing grade or 3 feet below the bottom of the footings whichever is deeper. The exposed surface should be scarified, moisture conditioned and compacted to a minimum of 90 percent relative compaction is attained prior to fill placement. Any fill material should be placed in thin lifts at near optimum moisture content and compacted to at least 90`percent relative compaction. c. Compaction. Soil to be used as engineered fill should be free of. organic material, debris, and other deleterious substances, and should not contain irreducible matter greater than three inches in maximum dimension. All fill materials should be placed in thin lifts, not exceeding six inches in their loose state. If import fill is required, the material should be of a low to non -expansive nature and should meet the following criteria: Plastic Index Less than 12 Liquid Limit Less than 35 Percent Soil Passing #200 Sieve Between 1.5% and 35% Maximum Aggregate Size 3 inches The subgrade and all fills should be compacted with acceptable compaction equipment, tout least 90 percent, relative compaction. The bottom of the exposed subgrade should be observed by a representative of Sladden Engineering prior to fill placement. Compaction testing should be performed on all lifts in order to ensure proper placement of -the fill materials. Table 2 provides a summary of the excavation and compaction recommendations. Sladden Engineering ` December 1, 201.0 -9- Table 2 SUMMARY OF RECOMMENDATIONS Project No. 544-10198 10-12-279 *Remedial Grading Excavation and recompaction within the building envelope and extending laterally for 5 feet beyond the building limits and to a minimum of 5 feet below existing grade or 3 feet below the bottom of the footings, whichever is deeper. Native / Import Engineered Fill Place in thin lifts not exceeding 6 inches in the loose state, compact to a minimum of 90 percent relative compaction within 2 percent, of the optimum moisture content. "Actual depth may vary and should be determined by a.representative of Sladden Engineering in the field during construction. e. Shrinkage and Subsidence. Volumetric shrinkage of the material that is excavated and replaced as controlled compacted fill should be anticipated. We estimate that this shrinkage could vary from 15 to 25 percent Subsidence of the surfaces that are scarified .and compacted should be between 1 and 3 tenths of a foot. This will vary depending upon the type of equipment used, the moisture content of the soil at the time of grading and the actual degree of compaction attained. FOUNDATION: CONVENTIONAL SPREAD FOOTINGS Load bearing walls may be supported on continuous spread footings and interior columns may be supported on isolated pad footings. All footings should be founded upon properly engineered fill and. should have a minimum embedment depth of 12 inches measured from the lowest adjacent finished grade. Continuous and isolated footings should have a minimum width of 12 inches and 24 inches respectively. Continuous and isolated footings placed on such materials may be designed using an allowable (net) bearing pressure of 1800 and 2000 pounds per square foot (psf) respectively. Allowable increases of 250 psf for each additional 1 foot in width and 250 psf for each additional 6 inches in .depth may be utilized, if desired. The maximum allowable bearing pressure should be 3,000 psf. The maximum bearing pressure applies to combined dead and sustained live loads. The allowable bearing pressure may be increased by one-third when considering transient live loads, including seismic and wind forces. All footings should be reinforced in accordance with the project structural engineer's recommendations. Based on the allowable bearing pressures recommended above, total settlement of the shallow footings are anticipated to be less than one -inch, provided foundation preparations conform to the recommendations described in this report. Differential settlement is anticipated to be approximately half the total settlement for similarly loaded footings spaced up to approximately 40 feet apart. Lateral load resistance for the spread footings will be developed by passive soils pressure against the sides of the footings below grade and by friction acting at the base of the concrete footings bearing on compacted fill. An allowable passive pressure of 300 psf per foot of depth may be used for design purposes. An allowable coefficient of friction 0.45 may be used for dead and sustained live loads to compute the frictional resistance of the footing placed directly on compacted fill. Under seismic and wind loading conditions, the passive pressure and frictional resistance may be increased by one-third. Sladden Engineering December 1, 2010 -10 - Project No. 544-10198 10-12-279 All footing excavations should be observed by a representative of the project geotedunical consultant to verify adequate embedment depths prior to placement of forms, steel reinforcement or concrete. The excavations should be trimmed. neat, `level. and square. All .loose,, disturbed, sloughed or moisture - softened soils and/or any construction debris should be removed prior to concrete placement. Excavated soil generated from footing and/or,utility`trenches should not be stockpiled within the building envelope or in areas of exterior concrete flatwork. SLABS -ON -GRADE In order to reduce the risk of cracking. and settlement, concrete slabs -on -grade must be placed on properly compacted fill as outlined in the previous sections. The slab subgrades should remain near optimum moisture content and should not be permitted to dry. Prior to concrete pour, all slab subgrades should be firm and unyielding. Disturbed soils should be removed and then .replaced and compacted to a minimum of 90 percent relative compaction. Slab thickness and reinforcement should be determined by the structural engineer we recommend a minimum floor slab thickness of 4.0 inches. All slab reinforcement should be supported on concrete chairs to ensure that reinforcement is,placed at slab mid -height. Slabs with moisture sensitive surfaces should be underlain with a moisture vapor retarder consisting of a polyvinyl chloride membrane such as 10-mil Visqueen; or equivalent: All laps within the membrane should be sealed and at least 2 inches of clean sand should be placed over the membrane to promote uniform curing of the concrete. To reduce the potential for punctures; the membrane should be placed on a pad surface that has been graded smooth"without any sharp,protrusions. If a smooth surface can not be achieved by grading, consideration should be given to placing a 1-inch thick leveling course of sand across the pad surface prior to placement of the membrane. SOLUBLE SULFATES Soluble sulfate concentrations were determined to be "low" -(less than 1,000 ppm). Based upon our preliminary testing, the use of Type V and/or sulfate resistant mix design will likely not be necessary. However, the soil should to be, retested for soluble sulfate concentration -after grading and compaction work is completed. Soluble sulfate content of the surface soil should be reevaluated after grading and appropriate concrete mix designs should be established based upon ppst-grading test results. UTILITY -TRENCH BACKFILL All utility trends. backfill should be.corripacted to a minimum relative compaction of 90 percent. Trench backfill materials should be placed in lifts no greater than six inches in their loose state, moisture conditioned (or air-dried) , as necessary to achieve, near optimum moisture conditions, and then mechanically compacted in place to a minimum relative compaction of 90 percent. A representative of the project soil engineer should test the backfill to verify adequate compaction. Sladden Engineering December 1., 2010 -11: Project No. S4.4-1.0198 10-12-279 EXTERIOR CONCRETE FLATWORK To minimize cracking of concrete flatwork, the subgrade soil below concrete flatwork areas should first be compacted to a minimum relative compaction of 90 percent. A representative of the project geotechnical consultant should observe and verify the density and moisture content of the soil prior to concrete placement. DRAINAGE All final grades should be, provided with positive gradients away from foundations to provide rapid removal of surface water runoff to an adequate discharge point. No water should,be'allowed to be pond on or immediately adjacent to foundation elements. In order to reduce water infiltration into the subgrade soil, surface water should be' directed away from building foundations to .an adequate discharge point. Subgrade drainage should be evaluated upon completion of the precise grading plans and in the field during grading. LIMITATIONS The findings and recommendations presented in this report are based upon an interpolation of the soil conditions between the exploratory boring locations and extrapolation of these conditions throughout the proposed building area. Should conditions encountered during grading appear different than those indicated in this report, this office should be notified. The use of this report by other parties or for other projects is not authorized. The recommendations of this report are contingent upon monitoring of the grading operation by a representative of Sladden Engineering. All recommendations are considered to be tentative pending our review of the grading operation and additional testing, if indicated. If others are employed to perform any soil testing, this office should be notified prior to such testing in order to coordinate any required site visits by our representative and to assure indemnification of Sladden Engineering. We recommend that a pre -job conference be held on the, site prior to the initiation of site grading. The purpose of this meeting will be to assure a complete understanding of the recommendations presented in this report as they apply to the actual grading performed. Sladden Engineering ` December 1, 2010 -12 - Project No. 544-10198 1.0-12-279 ADDITIONAL SERVICES Once completed, final project plans and specifications should be reviewed by use prior to construction to confirm that the full intent of the recommendations presented herein have been applied to design and construction. Following review of plans and specifications, observation should be performed by the Soil Engineer during construction to document that foundation elements are founded on/or penetrate into the recommended soil, and that suitable backfill soil is placed upon competent materials and properly compacted at the recommended moisture content. Tests and observations should be performed during grading by the Soil Engineer or his representative in order to verify that the grading is being performed in accordance with the project specifications. Field density testing shall be performed in accordance with acceptable ASTM test methods. The minimum acceptable degree of compaction should be 90 percent for subgrade soils -and 95 percent for Class I1 aggregate base as obtained by the ASTM D1557-91 test method. Where testing indicates insufficient density, additional compactive effort shall be applied until retesting indicates satisfactory compaction. Sladden Engineering December 1, 2010 =13 - Project No. 544-10198 t N 10-12-279 ` • REFERENCES Blake, T.; 2000, EQFAULT and EQSEARCH, Computer Programs for Deterministic and Probabilistic Prediction of Peak Horizontal Acceleration from Digitized California Faults. Boggs, S. Jr., (2001), "Principles of Sedimento'l69y and Strati a h " Prentice Hall, third edition California Building Code (CBC), (2007), California Building Standards Commission: ' Cao T., Bryant, W.A„ Rowshandel B., Branum D., Wills C.J., (2003), 'The Revised 2002 California Probabilistic Seismic Hazard Maps". GoogleEarth.com, 2010, Vertical Aerial Photograph for the La Quinta area, California, Undated, Variable Scale. ` Hart, E. W., and Bryant, W. A:, Revised 1997, Fault -Rupture Hazard Zones'in'California, Alquist-Priolo Earthquake Fault Zoning 'Act with •Index to Earthquake -Fault Zones Maps: State of California, Department of Conservation, -Division of'Mines and Geology Special Publication 42. 38 Pages. Supplements 1 and 2 were added on 1999.. - - 'Jennings, Charles W. (Compiler), 1994, Fault Activity Map of California and Adjacent Areas, California' Division of Mines and Geology, Geologic Data Map No. 6 - Riverside County Land Information Systems (RCLIS),available at r , http://www.tlmai.co.riverside.ca.us/gis/gisdeve)op.htmi: ! Rogers T.H (compiler), Jenkins, O.P (edition) (1965), Geologic Map of California, Santa Ana Sheet, sixth printing 1.992, California Division of.Mines-and Geology, 1: 250,000. TerraSever, Inc., 2002, Aerial Photographs and Topographic Maps at Various_ Scales. Available at www.terraserve.com x Tyley, S.J., (1974) Analog Model Study of the 'Ground -Water Basin of the Upper Coachella Valley, California, Geological Survey"Water-Suppley Paper 2027: United States Geological Survey(USGS) (1980) Indio 7.5 Minute. Quadrangle Map, 1:24000. .} United States Geological Survey (USGS) (2007);'"Detectiorf and Measurement of Land Subsidence Using ' Global Positioning System and, Interferometric'Synthetic Aperture Radar, Coachella Valley, California, 1996-2005", Scientific Investigations Report 2007-5251. 'United States Geological Survey (USGS) (2009)„"Seismic Hazard Curves and Uniform Response Spectra, Version 5.0.9a", updated10/21/2009: - k t . Sladden Engineering I InpIII�I � t� 7 : 1 I I a , _ ------ I •- .. .____ _ _ A. {1 r AVEWIF 77AVENUE y� S /r ' .Coacrtella valley! �rj : ,Cl.mela,y- ' . ,ir AVENUG' -J4 I � , t -• AVCNUC M. , • ----- ----� . 6__ `_ 15 �_ lA :_p i-I? 2D ..J AVENUE Jn AVFNU I ,j 1 I I u;. E.=-=^ >�.:r ll AVENUE b _ -- -- �` o 0 1 Mile 27 : -- Source: USGS (1980) "" SITE LOCATION MAP FIGURE Project Number: 544-10198 Report Number: 10-12-279 Sladden Engineering Date: December 1, 2010 r ' - ^� � r. • '' , _ , _. 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'ir _..k5�.'•t9f' '.( m>7L,,: .•�.�':__`'''' fS it _T. _J +f: 1�I );vR., ,.... ,,: 4C at �ilu�• kttt `� -::`' .,:;y �iy:imfai:r ti�, i�;`�. �:a ..c '-- aI� --_7 ,� , Q'Q�, .lF ,J�{..1};i'i' '�U n\i:.� .a t,� ./.'•a_.::'::, - ' t1. •r • - '..,5� t` -r:.q ~r g`t,_ijk'f?3}_.1:,-::ice _ 'f7n1 iv� °�: ........... - � .Ji C,luaternar�r lalre ileposits, f'N�.;,Ll't,_�:a:.i.f;c;_�,�;�.,,r:,l`1�.1�_�<:�r•`r--.,�-'�;'.`:ti, �`M1 :,k..:;:�.:.c 1 .: ?s`i YyY ^^z4y`r.(-�_f'^ r• !u�i_ 4,•'..._ �.� �I ! r•>), i, 114FJ ` _ !",t';:rr�.;t,J; . c�-:~t?if-,t� r-__�T����'Ci `if-_��;��',;t:�;;�-� -1 � •{ ..,' !, Ci'1F;a:-�u' �}.=y=;��- '�:; .�_;..r_��• z_.•i tclP,elt�raiyji�tt�. . --: t:: _ ._r..C: �.'ry: Vr::J •. .°''.c :�.�aa.;t.�'. .�yj::� lr 1•(',ill•�- ^J f�-�-: '�, �r l.,L::.f�J� T=., C•, / 0 5re�:._.•;,1. ply ,v �,cJ;�r.,�l4�`!i•''f.-F�r..�I1:,.�!(:j�;}r,/ �� Mt _.tt•; �i. -,�'-���';�. .,!°,: t p•: �,.,--:;ir:C=':• rrr /�,.�:t;::-�tQol„s. ;�``•• _ L,; L'•,,s, _..:.t" •ti v:.; ' i�E: '` �� i v_;: ��= Yg1•y;,�!- ate.' :'.t Sr- C ,:,.:. : _ 1, �! r '-' �� =R ,%•.F' =. �rT•'jtii7: IR-~-';1'S�1�'_' _ :; i."'r-a,---.�}y. •>?4J':'' ..i ;f, 1'�';v:;' Source:�Ro ers 1965.;;;_ ��,:�::y ' . wttj • %i {, �t. - I =j.:, ",,`� �': I. yS. . • REGIONAL GEOLOGICMAP, FIGURE Project Number: 544-10198 Report Number: .10-12-279 e. Sladden Engineering pater _ ',December.1, 2010 - � .-• c � ry , �1^+ .w -y t .. � �{,Q� • ,+- � ..�ti� a ,•- � •• i - i J : �f.it_ ,' i 17 _ _..... ___ !- -"'I jJ:1 I1_!_� -l.ai _ }_• _.i'_!_�y '3. .i _ '.i<' I� ...t) I .�--g�� _ BA-u-L� 1..�.. J ::!{� f .: �:: ��.. _. •...: !__.i: , I.f' �5,� —_ !ct;: :_i...��..i:!.— i S� l JIF i I(' 'i_t. --- J`:I �i i:.. �: ;,i:,;'<' �€ ;f j 41 r.. , hi1S_i_ ' -- _;_,_ _ -- -• ]^ i - ---- -� _� 7i FT DIU { gp _r-..... . .... ........ ® BH_2 Approximate Borehole Location and Designation BOREHOLE LOCATION PLAN Project Number. 544-10198 Report Number. 10-12-279 Sladden Engineering Date: December 1, 2010 FIGURE K i1 r APPENDIX A FIELD EXPLORATION For our field investigation two (2) exploratory borings were excavated utilizing a truck mounted hollow stem auger rig (Mobile B-61.). Continuous logs of the materials encountered were made by a representative of Sladden Engineering. Materials encountered in the boreholes were classified in accordance with the Unified Soil Classification System which is presented in this appendix. Representative undisturbed samples were obtained within our borings by driving a thin -walled steel penetration sampler (California split spoon sampler) or a Standard Penetration Test (SPT) sampler'with a 140 pound automatic -trip hammer, dropping approximately, 30 inches (ASTM D1586). The number of blows required to drive the samplers 18 inches was recorded in 6-inch increments and blowcounts are indicated on the boring logs.` The California samplers are 3.0 inches in diameter, carryi►lg brass sample rings having inner diameters of. 2.5 inches. The standard penetration samplers are 2.0 inches in diameter with an inner diameter of 1.5 inches. Undisturbed samples were removed from the sampler and placed in moisture sealed containers in order to preserve the natural soil moisture content. Bulk samples were obtained from the excavation spoils and samples were then transported to our laboratory for further observations and testing. Sladden Engineering ` s UNIFIED SOIL CLASSIFICATION SYSTEM MAJOR DIVISIONS TYPICAL NAMES CLEAN GRAVELS ' GW WELL GRADED GRAVEL -SAND MIXTURES r� GRAVELS WITH LITTLE OR NO cFINES GP POORLY GRADED GRAVELS, GRAVE, L-SAND N MIXTURES z° MORE THAN HALF COARSE FRACTION GM SILTY GRAVELS, POORLY -GRADED GRAVEL - IS SAND -SILT MIXTURES m LARGER THAN No.4 SIEVE GRAVELS WITH OVER GC ' CLAYEY GRAVELS; POORLY GRADED GRAVEL q F _ SIZE 12°� FINES caa SAND -CLAY MIXTURES 14 SW WELL GRADED SANDS, GRAVELLY SANDS oar G SANDS CLEAN SANDS WITH LITTLE OR NO FINES U SP POORLY GRADED SANDS, GRAVELLY SANDS MORE THAN HALF COARSE FRACTION IS SM SILTY SANDS, POORLY GRADED SAND -SILT SMALLER THAN No.4 SANDS WITH OVER MIXTURES • 2 SIEVE SIZE 12% FINES ' SC CLAYEY SANDS, POORLY GRADED SAND -CLAY ' MIXTURES I INORGANIC SILTS & VERY FINE SANDS, ROCK y MIL FLOUR, SILTY OR CLAYEY FINE SANDS, OR + CLAYEY SILTS WITH SLIGHT PLASTICITY SILTS AND CLAYS +' INORGANIC CLAYS OF LOW TO MEDIUM a LIQUID LIMIT LESS THAN 50 .' CL PLASTICITY, GRAVELLY CLAYS, SANDY CLAYS SILTY CLAYS CLEAN CLAYS 0L ORGANIC CLAYS AND ORGANIC SILTY CLAYS co co L� m 4 OF LOW PLASTICITY a N INORGANIC SILTS, MICACEOUS OR C9 dt� a • . I AM DIATOMACIOUS FIND, SANDY OR SILTY SOILS, F SILTS AND CLAYS: LIQUID ELASTIC SILTS LIMIT GREATER THAN CH INORGANIC CLAYS OF HIGH PLASTICITY, FAT W 60 CLAYS 0 • OH ORGANIC CLAYS OF MEDIUM TO HIGH PLASTICITY, ORGANIC SILTS HIGHLY ORGANIC SOILS Pt PEAT AND OTHER HIGHLY ORGANIC SOILS EXPLANATION OF BORE LOG SYMBOLS California Split -spoon Sample ®unrecovered Sample K�EMStafidard Penetration Test Sample Note: The stratification lines on the borelogs represent the approximate Groundwater depth boundaries between the soil types; the BORE LOG SLADDEN ENGINEERING Drill Rig: Mobil B-61 Date Drilled: 11/18/2010 Elevation: -40 Feet (MSL) Boring No: BH-1 a 2 _ t = •J S - o o v 0.. A .-. O 6 o CL i; o y r Description aV cn G S p p ram' 0. m (ri iE Sandy Silt (ML); grayish brown, dry to moist, low plasticity (Fill). 1 12 2 .. 4 6/8/8 30.3 1.1 105.3 6 Silty Sand (SM); light grayish brown, dry, loose, fine grained (Qal) 8 6/6/7 41.7 3.8 95.2 l0 �� Silty Sand (SM); light grayish brown, dry, loose, fine-grained (Qa)). 5/6/6 12.8 3.2' 14 76 - Silty Sand (SM); light grayish brown, dry, medium dense, fine- ' grained (Qal).' 18 3/3/3 94.7 36.7 20 Clay (CL); brown, moist, medium stiff, high plasticity (Qal). ?� 24 7/8/7 96? 38.7 26 Silt (ML); grayish brown, moist, stiff, low plasticity (Qal). 28 3, 4/5 38.2 7.0 .. 30 , Silty Sand (SM); light brown, moist, loose, fine-grained (Qal). 32 ... 4/5/5 11.8 3.9 34 36 - >: Sand (SP); light brown and gray, dry, loose, fine-grained (Qal). - 38 5/7/7 45.1 8.3 40 Silty Sand (SM); light brown, moist, medium dense, fine-grained 42 (Qal). r 9/9/9 15.8 4.3 46 Silty Sand (SM); light brown; dry, medium dense, fine-grained (Qal). 48 50 Sandy Silt (ML); light brown, moist, stiff, low plasticity (Qal). 3/6/6 62.9 23.7 Completion Notes:, PROPOSED HAMMOND RESIDENCE Termianted at -51.5 Feet bgs. 80810 VISTA LAZO, LA QUINTA, CALIFORNIA No Bedrock Encountered. Project No: 544-10198 No Groundwater or Seepage Encountered. IReport Page 7 No: 10-12-279 iI BORE LOG SLADDEN ENGINEERING Drill Rig: Mobil B-61 Date Drilled: ' - 11/18/2010 Elevation: 40 Feet (MSL) Boring -No: BH-2 'o' U o L .. a E o y a y. n, ' Description. _ Ln to(7 1 -= yr w co W .. t2 Sand (SP); light brown, dry, -medium dense, fine-grained (Fill). 8/10/10 9.3 0.5 :103.4 4/4/7 44.6 1.5 9-1.1 6 `: Silty Sand (SM); light brown, dry, loose; fine-grained (Qal). 4/6/9 56.0. 5.8 1U.3 70 Sandy Silt (ML); light Brown, moist, loose, fine-grained (Qal). ~ 14 6/7/7 - 16.8 4.12 • 105.2. `76 Silty Sand (SM); light grayish brown, dry to moist-, loose, fine- grained (Qal). + 020 Sandy Silt (ML); light brown, moist, medium stiff, low plasticity 2/3/5 '81-2, 31.7 892 (Qal) f, LL , 24 Termianted at -21.5 Feet bgs. ' + _ No Bedrock Encountered. 26 No Groundwater or Seepage Encountered.' 18 7307 36 r - 38 42. s 'a f • w } Y xt `. 44 it 46. r _ •L r 50 v r Completion Notes: , PROPOSED HAMMOND RESIDENCE 80810 VISTA'LAZO, LA QUINTA, CALIFORNIA Projecr No:.54440198 Page Report No:, 10-12-279 r z 4 APPENDIX B LABORATORY TESTING Representative bulk and relatively undisturbed soil samples were obtained in the field and returned to our laboratory for additional observations and testing. Laboratory testing was generally performed in two phases. The first phase consisted of testing in order to determine the compaction of the existing natural soil and the general engineering classifications of the soils underlying the site. This testing was performed in order to estimate the engineering characteristics of the soil and to serve as a basis for selecting samples for the second phase of testing. The second phase consisted of soil mechanics testing. This testing including consolidation, shear strength and expansion testing was performed in order to Provide a means of developing specific design recommendations based on the mechanical properties of the soil. CLASSIFICATION AND COMPACTION TESTING. Unit, Weight and Moisture Content Determinations: Each undisturbed sample was weighed and measured in order to determine its unit weight. A small portion of each sample was'then subjected to testing in order to determine its moisture content. This was used in order to determine the dry density of the soil in its natural condition. The results of this testing are shown on the Boring Logs. Maximum Density -Optimum Moisture, Determinations: Representative soil types were selected for maximum density determinations. This testing was performed in accordance with the ASTM Standard D1557-91, Test Method A. The results of this testing are presented graphically in this appendix. The maximum densities are compared to the field densities of the soil in order to determine the existing relative compaction to the soil. Classification Testing Soil samples were selected for classification testing This testing consists of mechanical grain size analyses. This provides information for developing classifications for the soil in accordance with the Unified Soil Classification System which is presented in the preceding appendix. This classification system categorizes the soil into groups having similar engineering characteristics..The . results of this testing is very useful in detecting variations in the soil and in selecting samples for further testing. SOIL MECHANIC'S .TESTING Expansion Testing: One (1) bulk sample was selected, for Expansion testing. Expansion testing was performed in accordance with the U13C Standard 18-2. This testing consists of remolding 4-inch diameter by 1-inch thick test specimens to a moisture content and dry density corresponding to approximately 50 percent saturation. The samples are subjected to a surcharge of 144. pounds per square foot and allowed to reach equilibrium. At that point the specimens are inundated with distilled water. The linear expansion is then measured until complete. Direct Shear Tests: One (1) bulk sample was selected for Direct Shear Tests. This test measures the shear strength of the soil under various normal pressures and is used to develop parameters for foundation design and lateral design. Tests were performed using a recompacted test specimen that was saturated prior, to tests. Tests were performed 'using a strain ' controlled test apparatus with normal pressures ranging from 800 to 2300 pounds per square foot. Sladden Engineering ' - la den Engineeringr 450 Egan Avenue, Beaumont CA 92223 (951) 84577743 Fax (951) 845-8863 Maximum Density/Optimum Moisture y ASTM D698/D1557 Project Number: 544-10198 December 8, 2010 Project Name: 80810 Vista Lazo, La Quinta Lab 1D Number: LN6-10464 ASTM D-1557 A Sample Location: B-1 Bulk @ 0-5' �. 3-1 Rammer Type: Machine 'Description. Brown Silty Sand (SM) Maximum Density: •118 pcf a y Optimum Moisture: 13% ' y Sieve Size °/� Retained 3/4" _ 3/8" #4 145 140 135 130 _ u a 125 c A I20 A -IIS 110 105 100 0 5 10 15 20, 25 Moisture Content, a o Buena Park Palm Desert o Hemet - = % la en n ineerin 450 Egan Avenue, Beaumont, CA 92223 (951) 845-7743 Fax (951) 845-8863 • ]xpansion Index • . i ASTM D 4829 ; Job Number: 544.10198 ... December 8, 2010 Job Name: 80810 Vista Lazo, La Quinta Lab ID Number: LN6-10464 "! Sample ID: B-1 Bulk C 0-5: ; Soil Description: Brown, Silty Sand (SM),` 1 ,' . ..F s:-, •Y • .1 � - :yam _ •F i, Wt of Soil—, Rnc: - F 554.2 Weight of Ring: 193.2 `. Wt of Wet Soil: ` 361'.0 Percent Moisture:, 11.6%' Wet Density, pc£ 115.2 Dry Densti, pef- t 103.2 ` Saturation: 49.5 0 a + a, Sladden Engineering 450 Egan Avenue, Beaumont, CA 92223 (951) 845-7743 Fax (951) 845-8863 Direct Shear ASTM D 3080-04 (modified for unconsolidated condition) Job Number: 544-10198 December 8, 2010 Job Name- 80810 Vista Lazo; La Quinta Initial Dry Density: 105.9 pcf Lab ID No. LN6-10464 Initial Mosture Content: 13.2 % Sample ID B-1 Bulk @ 0-5' Peak Friction Angle (0): 31 ° Classification Brown Silty Sand (SM) Cohesion (c): 260 psf . Sample Type Remolded @ 90% of Maximum Density - Test Results 1 2 - 3 4- Average Moisture Content, % 21.2 21.2 21.2 21.2 21.2 Saturation, % 97.0 97.0 97.0 97.0 97.0 Normal Stress, kps 0.739 1.479 2.958 5916 Peak Stress, kps 0.636 1,184 2.105 3.794 n.0 , i J y i.i 4.0 ' -1 -:. i( I- -.__......_.... ... i........-._..._- ... ... 5.0 1— _....... ......... 1 ---- G _ ......... . I I I I ca i......{... I -... . ... — I {:..:i I 2.0 - �......._.I i I ....� I -.I t.._i I ._.... 1 ..._ I , .._ �................ �....:� I I i --'--- ;_; ,_:_: I , t r t.o ---- -- I --- ► _ _ -__— .. I ----- ---- -I I I I ..�.._ ..... i ...._._.:.---._'__._.... .......... ..... ..... ........`..... �.. - ._....'......- --- ...'... :.. ... 0.0 0 1 2 3 4 5 6 Normal Stress, kps Sladden,Englneerong 450 Egan Avenue, Beaumont, CA 92223 (951) 845-7743 Fax (951) 845-8863 Gradation ASTM C117 & C136 , Project Number: 544-10198 , ;! ; ' December 8,2010 Project Name: 80810 Vista Lazo, La Quints Lab ID Number: LN6-10464 . Sample ID: B-1 Bulk @ 0-5' _ Soil Classification: SM ` } ';Sieve Sieve'. Percent ' Size, in Size, mm - Passing 50.8 100.0 1 1/2' 38.1 . 100.0 1„ 25.4 j 100.0 . 3/4" 19.1 100.0 1 /2 12.7 100.0 3/8" 9.53 100.0 #4 . 4.75 ' 99.9 #8 .2.36 *99.6 • , ' #16 . 1:18 -99.2 #30 0.60 98.8' #50 0.30 95.8 #100 F ' 0' 1"5 80.0 RI)nn n n'71C �� c' -Buena Park o Palm'Desert Hemet SladdenEng"ineering 450 Egan Avenue, Beaumont, CA 92223 (951) 845-7743 Fax (951) 845-8863 Gradation • ASTM C117 & C136 + Project Number 544-10198 , ', t December 8, 2010 Project Name: 80810 Vista Lazo, La Quints N. Lab ID Number:-LN6-10464 z Sample ID: B-1 #3 @ 15' Soil Classification: SM ' Sieve Sieve 4Percent Size; in r x Size, nun Passing 1++ 25.4- 100.0 . 3/4" 4 19.1 100.0 1/2++ 12.7 100.0 3/8" 9.53 - 100.0 4.75 100.0 #8 2.36 ' 100.0 #16 -1.18 "99.9 #30 0.60 98.5 #50 0.30 �74.9 ' #100" 710.15 39:4 0.001 Buena Park o Palm Desert Hemet .e 13 ladder. Engineering 450 Egan Avenue, Beaumont; CA 92223 '(951) 845-7743 Fax (951) 845-8863 Giadation ASTM C117 & C136 Project Number: 544-10198 December 8, 2010 Project Name: 80810 Vista Lazo, La Quinta ' Lab ID Number: LN6-10464 " Sample ID: B-2 #2 @ 5' Soil Classification: SM Sieve A Sieve Percent Size, in Size, mm Passing ` 1 „ 25.4 100.0 3/4" 19.1 100.0 -1/2" 12.7 100.0 3/8" .. 9.53 ' i 00.0 #4 , 4.75 100.0 . #8 2.36 100.0 ' #16 1.18 99.9.. #30 0.60 .. 99.3 #50 0.30 87.0 #100 0.15 67.8 ` #200 0.074 44.6 ladder Engineering'. 450 Egan Avenue,- Beaumont, CA 92223 (951) 845-7743 Fax (951) 845-8863 Gradation ASTM C117 & C136 Project Number: 544-10198 December 8, 2010 Project Name: 80810 Vista Lazo, La Quinta ` Lab ID Number: LN6-10464 Sample ID: B-2 #4 @ 15' Soil Classification: SM Sieve Sieve - Percent Size, in Size, mm Passing V 25.4 100.0 3/4" - 19.1 _ 100.0 1 /2" 12.7 100.0 3/8" 9.53 400.0 #4 4.75 - ' 100.0 #8 2.36. •99.9 , 416 1.18 " 99.7 #30 �� 0.60 97.1 #50 0.30 . ' 72.3 . #100 , 0.15 .38.8 0.074 16.8 100.000 10.000 1.000 0.100 , 0.010 Sieve Size, min '• 0.001 ladder Engineering- 450 Egan Avenue, Beaumont, CA 92223 (951) 845-7743 Fax (951) 845-8863, • one Dimensional Consolidation ti ASTM D2435 & D5333 i Job Number: , . � .. - :� • - 544-10198 �- December 8, 2010 Job Name: 80810 Vista Lazo, La Quinta Lab ID Number: LN6=10464 _ ` Iiiitial'Dry Density, pcf•. 102.0 Sample ID: B-1 #1 @ 5' - ; _` Initial Moisture, %: 1.1 • ti Soil Description: Brown Silty Sand (SM) . i -> Initial Void Ratio: 0.634 r Specific Gravity: ' 2.67 w - Hydrocollapse: 0.3% @ 0.702 ksf % Change in Height vs Normal Presssure Magm , ' a i 0 —3 .L -4 t U -6 -7 -8 -10 a tz �® fiz Consulting Engineers and Geologists