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BRES2015-0085 Geotechnical UpdateSladden-Engineering f 45090 Golf Center;Parkway, Suite F, Indio, CA 92201 (760) 863-M3 Fax (760) 863-0847 082 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 Avenu', Hemet, CA 92543[(951)766-8777 Fax (951) 766,-8778 February 27, 2015 Project No. 54-150574 15-02-095 Goodno Construction, Inc.= 35721 Linda Rosea goad Temecula, California 92592. Project: Proposed TomeiRe.sidence Via Mallorca - Lot 48C The Hideaway La Quinta, California. 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 preparedby Sladden Engineering dated October 12, 2003; Project No. 544-2199 Report No. 03-10-647 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 identified as Lot 48C is located along Via Mallorca within the Hideaway Golf Club development in the City of La Quinta, California. It is but understanding that the proposedresidencewill 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 placementof 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 t result& 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'j; the referenced grading ,report prepared by Sladden Engineering remain applicable for ,the design and construction, of the proposed residential structure foundations. I Sladden. Engineering Z February 27, 2015- -2- Project No. 544-15057 15-02-095 -,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. 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. 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. Passiveresistance 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 033 times the normal dead load forces. 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 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. Based on our field observations and understanding of local geologic conditions, the soil profile type judged applicable to this site is SD, 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). k.; Sladden Engineering February 27, 2015' =3- Project No. 544-15057 . 15-02-095 The seismic design category for a structure may be determined in accordance with Section 1613 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/II/III Site Class (Table 1613.3.2): D r Ss (Figure 1613.3.1):1.500g ` S1 (Figure 1613.3.1): 0:6848 Fa (Table 1613.3.3(1)):1:0 Fv (Table 1613.5.3(2)): 1.5 f Sms (Equation 16-37 (Fa X Ss)): 1.5008 Sm1 (Equation 16-38 (Fv X S1)):1.026g SDs (Equation 16-39(2/3 X Sms)):.1.000g SDI (Equation 16-40 (2/3 X'Sm1)): 0.6848 Seismic Design Category: D If you have questions regarding this letter or the referenced reports, please contact the undersigned. Respectfully submitted, SLADDEN ENGINEERING A ' Brett L. And on ANGEIESOGZ� w . Principal Engineer No. C4,,53 , ;,b3 , ur Exp. 9/30116 ' UVII_ SE gvm * ENGINl:EkING . CFCA�i�,%� Copies: 4; / Addressee i Sladden Engineering 5Nyr i5o57 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 -elements. Only then. can we be assured that the construction 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 measure(s) noted, or; (b) the criterion is considered insignificant and explicitly.so stated. fifes No Criterion M ® ----- -._............ ..... . .._... _....._ ..._........._ .................. - ....... . 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 -terra differential settlement. ® Foundation criteria to mitigate the.effects.of.varyng soli strength. . ® Foundation criteria to mitigate expected total and differential settlement. Any "Ito" answers to the above checklist should be noted as specific tre ulred corrections. �oPuoFESS�Q�< # # # BRCTT I `'• ANQFS�ly (Ds N 5q�s 2 CIV!L a\ GuNEER1Al;, it M ,a G r Sladden Engineering 10� EIVED' _W. 15090 Golf Center Parkway, Suite F, Indio, CA 92201 (760) 863-0713 Fax (76tT1853 6792 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 JUN 2 2015 800 E. Florida Avenue, Hemel, CA 92543 (951) 766-8777 Fax (951) 766-8778 - r CITY OF LA QUINTA February 27, 2015 ( "ft"08 %ELOPMENT 15-02-095 Goodno Construction, Inc: 35721. Linda Rosea .Road - Temecula, California 92592 RECEIVED Project: Proposed Tomei Residence Via Mallorca - i..ot 48C MAY 0 6 2015 The Hideaway La Quinta, California `.17Y OF LA QUINTA COMMUNITY DEVELOPMENT Subject: Geotechnical Update NT Ref: Geotechnical Engineering Report prepared by Earth Systems Southwest (ESSW) dated +' September. 22, 2000; File No. 07117-1.0, Report No. 00-09-772 ` Report of 'Testing and Observation During Rough Grading prepared by ESSW dated August 28, 2002; File No. 07117-1.1, 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 Repor No. 03-10-647' 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 identified as Lot 48C is located along Via Mallorca 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. r The subject lot was previously graded during the rough grading of the Hideaway project site and f 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 blong with minor cuts and fills to construct the individual building }gads 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,i�isAu �a e structural values included in the referenced grading report prepared b b� U1NTA remain applicable for the 'design",dnd",cons truction .of the .propose $d s' ® DEPT. foundations. iUIL�j�®®/ ED ' AP R FOR CONSTR CTION February 27, 201.5 -2 Project No. 544-15057 15-02-095' 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. 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 beat 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 1.500 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. 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.. Jf 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 2013 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.. 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. Th �bel� r�sNZ A additional coefficients and factors relevant to seismic mitigation fo n vy �- �tr�n/'� the 2013 California Building Code (CBC). �4 1 1 FEV DEPT' BUILDING & SA VE® A�CO�®UCTION FOR BY _ February 27, 2015 3- Project No. 544-15057 15-02-095 The seismic design category for, a structure may be determined in accordance with Section.1613 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 (''fable 1.5-1.):1/1'1/Ill . Site Class (Table 1613.3.2): D Ss (Figure 1613.3.1): 1.5005 Sr (Figure 1613.3.1): 0.6845 . Fa (Table 16'13.3.3(1)):1..0 Fv (Table 1613.5.3(2)):1.5 . " Sms (Equation 16-37 (Fa XSsl): 1.5008. Sm1(Equation 1.6-38 (Fv X SI 1): 1.0268 - SDS (Equation 16-39 12/3 X Smsl): 1.0008 SDI. (Equation 16-40 12/3 X Smi)): 0.6848 Seismic Design Category: D If you have questions regarding this letter ,or the referenced reports, please contact the undersigned. ; Respectfully submitted, SLADDEN ENGINEERIN - 'Brett L. And Principal Engineer ffay N SER/gv,n Ex r.ru ' ClViL . A C Auk. i'f _ Copies: 4 [Addressee �, (D C� ®G DEPT. gU1LD�N & SAFETY pa��� R ON FOR CQNST BY DATE=�� Shidilert Engineering S Lj L-1- 7 Oct LA QUiNTA Please verify that soils reports contain all of the above information. In addition, to assure continuity between•the investigationlreporting stage and the execution stage, please use the 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 Quanta Geotechnical Report Checkiisi 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 measures) noted, .or; (b) the criterion is considered insignificant and explicitly.so stated. Yes No Criterion _ -- - ®—Foti-nd-abon-citeria-base-d-uporrbearing-cap-ecity-of-rrafural-orc-ompacted--s, -11--- E3 Foundation criteria to mitigate the effects of expansive soils. ® Foundation criteria based upon bearing capacity. -of natural or -compacted soil. 0 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. ® Foundation criteria* to mitigate the effects.of.varying soil strength.. ® Foundation criteria to mitigate expected total and differential settlement, Any "No" answers to the•above checklist should be noted as specific r corrections. TA CITY ;, T .### BUILE �P TI CML BY DA ::...;