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BRES2019-0555 Geotechnical ReportSladden Engineering 45090 Golf Center Parkway, Suite F, Indio, CA 92201 (760) 863-0713 Fax (760) 863-0847 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 January 15, 2020 Mr. Ryan Thomas 73399 El Paseo Drive, Suite 101 Palm Desert, California 92260 Project: Proposed Custom Residence Lot 129 — Via Portofina The Hideaway La Quinta, California Project No. 544-20020 20-01-020 BRES2019-0555 CITY OF LA QUINTA BUILDING DIVISION REVIEWED FOR CODE COMPLIANCE DATE07/13/2020 BY JP 4,370SF S.F.D. Subject: Geotechnical Update Ref: Geotechnical Engineering Report prepared by Earth Systems Southwest (ESSW) dated September 22, 2000; File No. 07117-10, Report No. 00-09-772 Report of Testing and Observation During Rough Grading prepared by ESSW dated August 28, 2002; File No. 07117-11, Report No. 01-07-718 Report of Testing and Observation During Rough Grading prepared by Sladden Engineering dated October 12, 2003; Project No. 544-2199 Report No. 03-10-647 In accordance with your request, we have reviewed the above referenced geotechnical reports as they relate to the design and construction of the proposed custom residence. The project site (identified as Lot 129) is along Via Portofina within the Hideaway Golf Club 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 slabs on grade. The subject lot was previously graded during the rough grading of the Hideaway project site and was subsequently regraded. The rough grading included over -excavation of the native, surface soil along with the placement of engineered fill soil to construct the building pads. The regrading included processing the surface soil along with minor cuts and fills to construct the individual building pads to the current configurations. Some additional over -excavation was performed in areas where the building envelopes were reconfigured. The most recent site grading is summarized in the referenced Report of Testing and Observations During Rough Grading prepared by Sladden Engineering along with the compaction test results. The referenced reports include recommendations pertaining to the construction of residential structure foundations. Based upon our review of the referenced reports, it is our opinion that the structural values included in the referenced grading report prepared by Sladden Engineering remain applicable for the design and construction of the proposed residential structure foundations. Sladden Engineering January 15,2020 Project No. 544-20020 20-01-020 The allowable bearing pressures recommended in the referenced grading report prepared by Sladden Engineering remain applicable. Conventional shallow spread footings should be bottomed into properly compacted fill material a minimum of 12 inches below lowest adjacent grade. Continuous footings should be at least 12 inches wide and isolated pad footings should be at least 2 feet wide. Continuous footings and isolated pad footings should be designed utilizing allowable bearing pressures of 1500 psf and 2000 psf, respectively. Allowable increases of 300 psf for each additional 1 foot of width and 300 psf for each additional 6 inches of depth may be utilized if desired. The maximum allowable bearing pressure should be 3000 psf. The recommended allowable bearing pressures may be increased by one-third for wind and seismic loading. Based on the recommended allowable bearing pressures, the total static settlement of the shallow footings is anticipated to be less than one -inch provided that foundation area preparation conforms to the recommendations described in this report. Static differential settlement is anticipated to be approximately one-half of the total settlement for similarly loaded footings spaced up to approximately 40 feet apart. Lateral forces may be resisted by friction along the base of the foundations/slabs and passive resistance along the sides of the footings. A friction coefficient of 0.50 times the normal dead load forces is recommended for use in design. Passive resistance may be estimated using an equivalent fluid weight of 300 pcf. If used in combination with the passive resistance, the frictional resistance should be reduced by one third to 0.33 times the normal dead load forces. The bearing soil is non -expansive and falls within the "very low" expansion category in accordance with 2016 California Building Code (CBC) classification criteria. Slab thickness 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 at 24 inches on center in both directions. 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. The seismic design category for a structure may be determined in accordance with Section 1613 of the 2019 CBC or ASCE7-16. According to the 2019 CBC, Site Class D may be used to estimate design seismic loading for the proposed structures. The 2019 CBC Site Specific Seismic Hazard Analyses are attached. Sladden Engineering January 15, 2020 -3- Project No. 544-20020 20-01-020 Because the lot has been previously rough graded, .the remedial grading required at this time should be minimal provided that the building falls within the previously established building envelope. The building area should be cleared of surface vegetation, scarified and moisture conditioned prior to precise grading. The exposed surface should be 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. If you have questions regarding this letter or the referenced reports, please contact the undersigned. Respectfully submitted, SLADDEN ENGINEE Brett L. Principal Engin .r , SER/ra ! OFESS/041 `q( BR E<1, fit ANDERSON J. No. C45389 ri m CIVIL * ENGENG ;- rt` �,97 o�INCAERIS-1FOCt. Copies: 4/ Addressee Matthew J. Cohrt Principal Geologist f U Sladden Engineering 2(� - oI- 62--0 Please verify that soils reports contain all of the above information. In addition, to assure conlinufty between the Investigation/reporting stage and the execution stage, please use - tha following checklist to verify that the conclusions and recommendations in the report cover all the required elements, only then can we be assured that the construction documents address all of the site soil conditions. La Quints 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 measure(s) noted, -or; • (b) the criterion is considered insignificant and explicitly so stated. .No Criterion ❑ Foundation criteria based upon bearing capacity of natural or compacted soil_ Q Foundation criteria to mitigate the effects of expansive soils. Foundation criteria based upon bearing capacity, of natural or compacted soil. Foundation criteria to mitigate the effects of liquefaction. Foundation criteria to mitigate the effects of seismically. induced differential settlement. - ® Foundation criteria to mitigate the effects of long-term differential settlement_ 7 Foundation criteria to mitigate the effects of varying soil strength. fal Foundation criteria to mitigate eXpected total and differential settlement, Any No" answers to the. above checklist should be noted as specific required corrections, # # # o?E� on 11.'Ell- L. c. DERSOf1 o. 4538 CIVIL IN«.R1NG• `T 147 4� Project: Lot 129 - Via Portofina Project Number: 544-20020 Site Lat/Long; 33.6681 /-116.2548 Controlling Seismic Source: San Andreas REFERENCE Site Class Site Class D - 21.2.2.01) Site Class D - 21.2.2.01) 0.2*(Sor/Sos) Sos/Sos Fundamental Period (12.8.2) Seismic Design Maps or Fig 22-14 2/3*SMs Fv*Ss F„ (Table 11.4-2)[Used for General Spectrum] Design Maps Design Maps Design Maps Design Maps Design Maps Equation 11.8-1 Section 21.5.3 Design Maps Design Maps RISK COEFFICIENT Cr - At Perods <=0.2, Cr=CRS Cr - At Periods >=1.0, Cr=Cr1 Cr - At Periods between 0.2 and 1.0 use trendline formula to complete NOTATION VALUE A, B,C, D,EorF D Fa 1 F„ 2.5 To 0.138 Ts T TL Sol 5M1 F„ SMs SIDS Ss FPGA PGA PGAM 80%of PGAM CR1 Crs Cr Cr 0.692 Period 8 0.693 1,039 1.7 1.502 1.001 0.616 (Site Class D (Measured) only) 0.659 0,725 0.580 0.888 0.905 0.905 0,888 Period Cr 0.200 0.905 0.300 0.903 0.400 0.901 0.500. 0.899 0.600 0.897 0.680 0.895 1.000 0.888 DETERMINISTIC SPECTRUM AND LOWER LIMIT 0 Y N Q W 0 0 m 3 C N 0 O 10 W 00 0J 110 a v nc to • or o 9 alC V 3 C O N R. W es • C 3 O ✓ H a ea E C U • E c C 0 0 a 2 ID tn O 9 .a N m co DETERMINISTIC MCE 84 FRACTILE n 0 V Lit a-1 N N N 0 0 N 0 0 0 0 0 0 0 0 vl M 0 ID 0) el CY CO M N w a 01 0t ill 0 0 0 0 0 0 0 to 'Cr M N v 0 n IN r DOOt O O et Al o N to tto to N to N CA Mvt O Oo 6 6 O O ci ci vi r4 'i ci c-I ri ei r40 0 I -I a-i 0 0 0 0 DETERMINISTIC LOWER LIMIT N ON1 m 00 m N N up %- 1.00 LLn CO 0 0 0 0 0 0 0� 0 0 N 0 0 6 A- CO 00 01 O O el N to to N to I in IA N to en M 6 0 6 6 O O O ri r4 ei a-i a -I ei a -I N N r4 ti ay 0 O O. 0 DETERMINISTIC (RAW) N O t M ri IN N N LD 0 N 0. M tD el 00 CO CO el N to 0 ID t00 r A. N 0000 N co CA O O 0) N IY) Al AI V MV CN' m N 001 n t^l1 a 6 . 6 O 6 O O O ri 'ti 'i ri e-I c-I ri ri N N ati a-i O O O.O 'O O va. 1110000000000000000000000 O N M d' to t0 CO 01 O N In 0 0 0 0 0 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ei ei a -I N M C' to tO lO O N O O O O 0 0 o 6 0 06 O O O O O O 0 0 0 0 a-i t-i N M 4 N Deterministic PGA: 0.697 N 0 0 ro O N a c Project No: 544-20020 U K cc U 00 o v 2 o o k o,/?o n O Q z tun Q—< ��Q Z „(00 0 ce N Z 0 03 O • m O C I- Al 0 0 N N '^ 0 00 C CO C J ; Y O t v a `o Ep o 0 0 —Deterministic Lower Limit —II—Deterministic (Raw) Deterministic MCE I 1 I I I I !' i :1 I ; J----,- — I k -I-----'- - - - ----- — - I r I 11 4 I i I I 1 I I I( I I j i t ! l•i— I l I 1 1 I I 'IC MCER- I � c I ACCELERATIONS I 1 -- I I I I j � - i. ,_ 1; 1 �_ I - ------- 1 TI ___.___ �I.___ [4 _ 1 I _, ..._ I I 5101 W-W-I- o—Ir W 1f W I vs 1 I I 1 —1 1 + i I - I I- 1 I I r_ ( r I r I — i I I— i —- 1 I -__, I I 1 ti_— , ._ _ __ _ _ ______1__.. 1 I I I , : I 1 I S I` ! 1 , - I- L. I 1 _- I 1 --L- - r - s— --`---_I j— �— .; I 1 I , I .._..1 .-.-- I �... _I._ 11 ------- . I 1 1 -- { — - --- j — --------------1-- ,�. ---- r - L s ..._ I I ...— - a I . -- — i i J O O (3) uolaeaala»v 0 0 O m 8 N .4 O Period (seconds) Risk Coefficient Probabilistic Period B - A C -B C -Y Mean (CR) MCE N ONO . O N 000 O 0l ONI O M Ol O Cr N M ul N 00 00 01 0 CO M 01 N .-1 N 0 0 CO N O O N M Ct 111 tD CO CO Cr 0 Ul Cr N cN-I n LLfl CI' M . ri ri ri ri ri ri ri ri rl ri ri ri rl ri ri O O O O ul 0 01 0 to 0 01 0 M 0 01 0 ul 0 al 0 M 0 of 0 to 0 Ol 0 LA 0 al 0 to 0 of 0 ul 0 Ol 0 to 0 01 0 111 0 01 0 u1 0 01 0 M 0 Ol 0 r1 0 Ol 0 01 al CO 0 N Ol 00 0 lfl 01 00 0 CO CO CO 0 CO CO 00 00 00 CO 00 CO CO CO CO CO 0 0 0 0 CO 00 CO 6 01 O 01 O O ri 0 r1 N ri N ri M r4 Ct r4 tf1 ri N ri 00 r1 O N O N 01 r1 CO ri N c-I t0 11 CI' r1 N CO tD Ct r1 O O O M O LID O ri N O ri N r1 ri N C-I ri CI' N r1 N M .4 ri ul r1 0 to ri r1 N r1 O 01 ri N CD N 01 r 1 N 0l r1 N N 0 N N N 01 N ri ri CO t0 r1 N Cr 44 r1 CO 0 Cr M CO to Cr r4 O O O N M O 01 CO O 01 CO O M 0l O rl u1 Cf 0 0 r1 rl r1 ri 0 M N-i 01 M r1 N CY ri 0 to ri 0 N ri 0 Ol ri M CO ri M N ri CO t0 ri 01 Vl ri V ul r1 CO M ri LA to tD rt N 01 tD ul r1 O O O tll Cr O M Ol O 01 O 0 0 0 t-I M CI' tD N 01 01 N 01 01 N M ri ri r1 ri .-i .-I ri ri ri ,-i ri ri ri ri ri ri ill CO0 N 0 t D CY r1 6 6 6 00 M 6 1n 0 O 0 0 O 0 0 O 0 0 O 0 0 O 0 0 O 0 0 O 0 0 0 r1 O. 0 0 rr1 0 t0 rrI 0 0 ON 0 0 m 0 0 y 0 0 uu 0 0 too 0 0 two 0 0 0 0 0 0 o NO 0 0 0 rl ri N o'i Cf 0 0 ul Probabilistic PGA: 0.877 U cc V 00 2 O o CO N 0 in co O U' 0 N V 1n < N '. • Q to • Z vi o Z O W W N Z o O ro O O C 0 QN 0 O0 • C 0 O N } v D. z o E o m u w U u Project No: 544-20020 —II —Boo re -Atkinson {2008) NGA USGS 2008 MRC 1 1 1 i i I I 1 I I_ — i I I 1.__ 1 f-- 1 ' I 1 DBABILiSTIC'MCE I -;-1-_1--1 ESE1 ISPONE ACCELATIONS `j i -,.._1- 1 1 1 i -I._ ' 1 y I f I I 1 I I I , I 4 I— 1 I t I I I —�_ I f ( h { 1 '. , i •- I jJ I I . I-._i . — ..._1..1 I a._ II J ; i 1 s 1 • - — • , --_ I I i i I f 1 1 I / _. _ .. _ I.— 1 1 1 , J 1 i I— i — i _ Ir 1 i (fl) uopeAalaooy g 0 fi 4 a 80% General Response Spectrum M 011 a 01 a 01 CO M n N n N .-I rl .-I rl ri rl r1 rl rl r1 r-1 ri N tD m a N n iA 01 r1 fn 01 N N 01 N 01 m ID 0 M 01 0 0 0 0 0 0 0 0 0 0 0 0 01 ri CO 01 t0 IN 00 01 NH m m a a a to to t0 t0 n n n 00 00 CO 0 00 00 0 CO 00 00 0 00 CO t0 ID d d Ol a N 0 0 d0 O O O 6 6 O O O O O O O O d d O 0 0 0 0 0 0 666666 O O 1- F W a rz 0 W 0 H W F to N .i a n ri 00 r-1 a CO c-1 0 rl r1 !Ai ri rl ri ri ci rl e-I r1 rl if) 0 01. Al n t0 rl M 01 N M n Ha a. 01 m N N 01 0 0 0 0 0 0 0 0 0 0 0 0 ri n N O1 IN a m n M a a V1 1n tO tp r IN CO CO 01 01 0 0 0 0 0 0 0 0 0 0 0 00 n n l0 to m N ri rl • O O O O O O O O O O O rl c-I .-i .-i Hi r1 ri ri ci c-1 Hi .-i O O d d 0 d 0 0 0 0 0 0_ 01 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 o r1 M a 01 t0 00 01 0 rN N M to t0 IN 00 m 0 0 0 0 0 a CO 01 0 If) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 c-I ri r1 ci ci ri ci r1 r1 N m a N tO t0 tO CO 01 01 O N O 0 0 0 O Odd O 0 0 0 0 0 0 0 d 0 0 0 0 0 0 0 0 0 O o d d 0 ri rl N M a vt Design Response Spectrum (Sa) a s t0 M to n 01 N a a a m O O O O Cr 0 01 O N 00 lA d CO 01 0 O N 01 t0 0 ci m N 0 m 01 N. 0 IN 01 0o 0 0 0 0 ri 0 0 o ri 0 0 0 .-i 0 0 0 r 0 0 0 Hi 00 00 0 O a 00 n 0 01 ri 01 a N ID n M CO n 111 m N N O O O d d 0 u t NW o. U m al ++ l%1C) n 0 a 01 N ri a CO t0 N N n O O O O ri M co O N n oo O n co M O N a O Hi I0 01 O ri 0 to 01 IA ri N Hci 0 0 1n H 0 0 Y1 Hi 0 0 0 Hi 0 0 0 H 0 0 N r1 N CO a r-i ei N 0 0 00 n in N 01 lA r1 a N r1 INN a M ri r1 O O O O Deterministic MCE tut y CO N HC' CO M ^ W dN' o At n 0 00 01 ° O O O O O O O ri O0i 0 ri rl 0 HO to e-I 0 ri ill to 0 c-I c-1 c-i vl ci M 00 CO 0 N 4^ M I^it dN' t-i e1 m n O a O 0 Probabilistic MCE n N 0 to 0n0 CO000 01 O 6 O O a O r1 n 0 ri M N H in m Hi n Cr Hi CO N ri CO 0 r1 01 CO ri 0 CO r1 CO N Hi 01 t0 r1 01 01 r1 N a Hi r1 Al N rN ri rl 0 0 CO n N N a 01 6 O O O -0 O 'it 0, 01 0 0 0 ON M a 0 0 0 0 O O O O 0 01 0 O 0 0 LOCO 0 0 O O 0 O1 0 O 0 O ri O 0 rV ci O 0 M r 0 0 0 N 0 0 0 m 0 0 0 Cr 0 0 0 lA O 0 0 t0 O 0 00 t0 d 0 0 0 0 0 0 0 0 0 0 0 0 0 N 0 0 0 0 r1 ri N 01 a V1 : Section 21. r1 N L O t 0J N a 0 CC n n N n 01 w to w U U U U < Q c Q 0 0 0 to O to to 01 0 01 ri m n in 0 .-1 ri Hi A 0 01 O o 22 m tA w th n m to Site Specfic PGA„: 0 0 4 Ln �— Probabilistic MCE —— Deterministic MCE mg Site -Specific MCE ---a+—Design Response Spectrum — +—ASCE 7 Section 11.4.6 General Spectrum —4 - 80% General Response Spectrum Sladden Engineering 0 0 0 i 1 i I 1 _ i. I ELERATIONS - ' I HI' I I 1 , _.IL. 1 -I- 1 1 ' I! j- r 1 1 — i ....f I i -; i 1 , --!- `-1., J I ; - -a- 1 i� i 1 -1 J I -!--? - - _ _.__.. - ! r' 1 �_ - L- ----i- I H I 1 1-- -t-_J__ i -I-- ----i I I ! -�- I-- 1 i I 1 - ;— 1 r I I ! 1- 1 • i i ! ' !_ I _ _ , -SPECTRAL RI I I I ilrr E i I I 1 I__..._11------____._. • i 1-I � .._ . .I _ .. ---jr--- - i -_.. - - ! - I t _ 1 1_ ..I i i i 1 7 _ , — t r _ i. I- i 1 ---1 , I-�_ I -- . 1 1 i_ ! —� J L I _� 1 r i ; 1 i I 1 i 1 —1 ,----).-----..r r __., ., _i_ _L___J_____I _ .1_._. - ! - I 1 -= �.k -. - O ti 0 ri (8) uoiaeiapa3v 0 0 O O O 0 Y 0 a 0 N 0 o 0 0 J.S. Seismic Design Maps https://seismicmaps.orgf Lot 129 - Hideaway, La Quinta Latitude, Longitude: 33.6681, -116.2548 u ro Hideaway Golf Club Go ' gk. Date Design Code Reference Document Risk Category Site Class Type Value Ss 1.502 via Portofino Via Porto ffoo 1/1612020, 8:23:14 AM ASCE7-16 IV D - Stiff Soil Description MCER ground motion. (for 0.2 second period) Si 0.616 MCER ground motion. (for 1.0s period) SMS 1.502 Site -modified spectral acceleration value 3M1 null -See Section 11.4.8 Site -modified spectral acceleration value SDS 1.001 Numeric seismic design value at 0.2 second SA Sol null -See Section 11.4.8 Numeric seismic design value at 1.0 second SA OSHPD Type Value Description SDC null -See Section 11.4.8 Seismic design category Fa 1 Site amplification factor at 0.2 second PI/ null -See Section 11.4.8 Site amplification factor at 1.0 second PGA 0.659 MCEG peak ground acceleration FPGA 1,1 Site amplification factor at PGA PGA 0.725 Site modified peak ground acceleration TL 8 Long -period transition period in seconds SsRT 1.8 Probabilistic risk -targeted ground motion. (0.2 second) SsUH 1.989 Factored uniform -hazard (2% probability of exceedance in 50 years) spectral acceleration Ss0 1.502 Factored deterministic acceleration value. (0.2 second) S1RT 0.699 Probabilistic risk -targeted ground motion. (1.0 second) S1 UH 0.787 Factored uniform -hazard (2% probability of exceedance in 50 years) spectral acceleration. S1D 0.616 Factored deterministic acceleration value. (1.0 second) PGAd 0.659 Factored deterministic acceleration value. (Peak Ground Acceleration) CRS 0.905 Mapped value of the risk coefficient at short periods `.: Map data fJ2020 1 of 3 1/16/2020, 8:23 AM S. Seismic Design Maps https://seismicmaps.org/ Type Value Description CRt 0.888 Napped value of the risk coefficient at a period of 1s of 3 1/16/2020, 8:23 AM S. Seismic Design Maps https://seismicmaps.org/ DISCLAIMER While the information presented on this website is believed to be correct SEAOC /OSHPD and Its sponsors and contributors assume no responsibility or liability for its accuracy. The material presented in this web application should not be used or relied upon for any specific application without competent examination and verification of its accuracy, suitability and applicability by engineers or other licensed professionals. SEAOC / OSHPD do not intend that the use of thls information replace the sound judgment of such competent professionals, having experience and knowledge in the field of practice, nor to substitute for the standard of care required of such professionals in interpreting and applying the results of the seismic data provided by this webslte. Users of the information from this website assume all liability arising from such use. Use of the output of this webslte does not imply approval by the governing building code bodies responsible for building code approval and interpretation for the building site described by latitude/longitude location in the search results of this website. of 3 1/16/2020, 8:23 AM