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BRES2019-0162 Geotechnical ReportSladden Engineering 45090 Golf Center Parkway, Suite F, Indio, CA 92201 (760) 863-0713 6782 Stanton Avenue, Suite C, Buena Park, CA 90621 (7.14) 523-0952 450 Egan Avenue, Beaumont, CA 92223 (951) 845-7743 Fax (951) 845-8863 800 E. Florida Avenue, Hemet, CA 92543 (951) 766-8777 September 10, 2018 Project No. 544-18331 ' Mr. & Mrs. Jay & Cindy Ihlenfeld 81 Wildwood Beach Road Mahtomedi, Minnesota 55115 Project: Proposed Custom Re; 55705 Cherry Hills Di PGA West Stadium C La Quinta, California Subject: Geotechnical Update r RECEIVED � MAY 2 3 2019 INTERVJCST CONSULTING GROUP 18-09-451 RECEIVED MAY 19 ma BUILDING DIVISI I CITY OF LAQUINTA REV@FWED FOR DESIGN ND DEVELOPMENT DEPARTMENT r,0DF 2�SZ�19-o16z ,CQMPLIpN(',E f . Ref: Geotechnical Investigat i�ft,=7"1d �y'Sladd rnFlE.nh ing dated Ma�y�� 2014; Project No. 544-14102, Report No. 14-04- In accordance with your request, we have reviewed the above referenced geotechnical report prepared for a nearby project site as it relates to the design and construction of the proposed custom residence. The project site is located at 55705 Cherry Hills Drive within the PGA West Stadium Course development in the City of La Quinta, California. It is our understanding that the proposed residence will be of relatively lightweight wood -frame construction supported upon conventional shallow spread footings and a concrete slab on grade. The referenced report includes recommendations pertaining to the design of the residential foundations and for remedial grading. Based upon our review of the referenced report and our previous experience in the site vicinity, it is our opinion that the structural values provided in the referenced report should be applicable for the design and construction of the proposed residential foundations. Because the lot has been previously rough graded, the remedial grading required at this time should be minimal provided that the building area that falls within the previously assumed building envelope. The building areas 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 prior to fill placement. The previously removed soil and any fill material should be placed in thin lifts at near optimum moisture content and compacted to at least 90 percent relative compaction. Sladden Engineering www.Sladdenengineering.com September 10, 2018 -2- Project No. 544-18331 18-09-451 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 compacted engineered fill soil 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 pressures of 1500 and 1800 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 2,500 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 soil 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 250 psf per foot of depth may be used for design purposes. An allowable coefficient of friction 0.40 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 California Building Code (CBC) classification criteria. The seismic design category for a structure may be determined in accordance with Section 1613 of the 2016 CBC or ASCE7. According to the 2016 CBC, Site Class D may be used to estimate design seismic loading for the proposed structures. The 2016 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 Si (Figure 1613.3.1): 0.633g 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 Sm1 (Equation 16-38 (Fv X Si)): 0.949g SDS (Equation 16-39 12/3 X Sms)): 1.000g SM (Equation 16-40 12/3 X Sml}): 0.633g Seismic Design Category: D September 10, 2018 -3- Project No. 544-18331 18-09-451 If you have questions regarding this letter or the referenced report, please contact the undersigned. Respectfully submitted, SLADDEN ENGINEERING Brett L. Anderson Principal Engineer SER/ra Copies: Q Addressee �G nENGINEERING 2F CiNG _ / 6 33 / aq-N-Yl Please verify that soils reports contain all of the above infomlation. 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 Repoi$ 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) no or, (b) the criterion is considered insignificant and explicitly so stated. Yes No CPiterion ❑ Foundation criteria based upon bearing capacity of natural or compacted soil. 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. Foundation criteria to mitigate the effects of varying soil strength. X ❑ Foundation criteria to mitigate expected total and differential settlement. Any "No" answers to the above checklist should be noted as specific required corrections. Sladden Engineering 45090 Gulf Center Parkway, Suite F, India, CA 92201 (760)853-0713 6782 Stanton Avewc, Suile C. Buena Park, CA 90621 (714) 523-0952 450 Egan Avenue, 8eaun=4 CA 92223 (95 i) $45-77-13 800 E. Florida Awnue. Hemet CA 92543 (951) 766-8777 www.Sladdenengincering.com June 27, 2019 Project No. 544-18331 19-06-308 Mr- & Mrs. Jay and Cindy Ihlenfeid �S -1 i 81 Wildwood Beach Road --. - DI Ji Mah tomedi, Minnesota 55115BUILDING��. 'r��.i!;�.+� •� Project: Proposed Custom Residence F-Ivf� � 6J:_.d. r� ! 55705 Cherry Hills Drive PGA West Stadium Course (�j%I��j'', La Quinta, California [DA' Subject: Foundation Plan Review— - Ref: Geoted-mical Update prepared by Sladden Engineering dated Septemb q 2018; Project No. 544-18331, Report No.18-09-451 In accordance with your request, we have reviewed the Foundation Plans and Details prepared by B.G. Structural Engineering, Inc. for the proposed custom residence to be constructed at 55705 Cherry Hills Drive within the PGA West development in the City of La Quinta, California. Based on our review, it is our opinion that the recommendations provided in the above referenced Geotechnical Update as well as the previous geotechnical reports have been properly incorporated into these plans. If you have questions regarding this memo or the referenced report, please contact the undersigned. Respectfully submitted, SLADDEN ENGINEERING �w Brett L. AnAH ERso mderson � No. C45389 Principal Engineer CML Letter/nh CALlI Copies: 4 / Addressee Sladden Engineering rvww.Sladdenengineering. cony n �NL