Loading...
BRES2019-0178 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 May 30, 2019 Project No. 544-19181 19-05-249 West Coast Builders, Inc. 78005 Wildcat Drive, Suite 104 Palm Desert, California 92211 Project: Proposed Custom Residence 57330 Peninsula Lane PGA West — The Peninsula La Quinta, California Subject: Geotechnical Update Ref: Geotechnical Engineering report prepared by Buena Engineers, Inc. dated April 17, 1986; Project No. B-14413-P3, Report No. 86-4-209 Geotechnical Update report prepared by Sladden Engineering dated July 8, 2002; Project No. 544-2125 Report of Observations and Testing During Fine Grading prepared by Sladden Engineering dated March 17, 1999; Project No. 522-8096R In accordance with your request, we have reviewed the referenced geotechnical reports as they relate to the design and construction of the proposed custom residence. The project site is located at 57330 Peninsula Lane within the PGA West development in the City of La Quinta, California. It is our understanding that the proposed residential structure will be of relatively lightweight wood -frame construction and will be supported by conventional shallow spread footings and concrete slabs on grade. Based upon our report review, our previous experience on the site and our understanding of the proposed construction, it is our opinion that the structural values recommended in the previous geotechnical reports remain applicable for use in foundation design. Conventional shallow spread footings should be supported by 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 may be designed utilizing allowable bearing pressures of 1800 psf and 2000 psf, respectively. Increases in allowable bearing pressures may be realized with increased footing size. Allowable increases of 200 psf for each additional 1 foot of width and 250 psf for each additional 6 inches of depth may be utilized, if desired. The maximum allowable bearing pressure should be 2500 psf. The recommended allowable bearing pressures may be increased by one-third when considering wind and seismic loading. May 30, 2019 -2- Project No. 544-19181 19-05-249 Resistance to lateral loads can be provided by a combination of friction acting at the base of the slabs or foundations and passive earth pressure along the sides of the foundations. A coefficient of friction of 0.45 between soil and concrete may be used with dead load forces only. A passive earth pressure of 300 pounds per square foot, per foot of depth, may be used for the sides of footings that are placed against properly compacted native soil. 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 18 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 cannot 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 2016 CBC or ASCE7. According to the 2016 CBC, Site Class D may be used to estimate design seismic loading for the proposed structures. This assumption should be verified by the project structural engineer. The 2016 CBC Seismic Design Parameters are summarized below. Occupancy Category (Table 1604.5): I/II/111 Site Class (Table 1613.5.5): D Ss (Figure 1613.5.1: 1.500g SI (Figure 1613.5.1: 0.609g Fa (Table 1613.5.3(1)): 1.0 Fv (Table 1613.5.3(2)): 1.5 Sms (Equation 16-36 {Fa X Ss}): 1.500g Smi (Equation 16-37 {Fv X Si}): 0.913g SDS (Equation 16-38 {2/3 X Sms}): 1.00Og SD1(Equation 16-39 {2/3 X Smi}): 0.609g Seismic Design Category: D Sladden Engineering May 30, 2019 -3- Project No. 544-19181 19-05-249 Because the lot has been previously graded, the remedial grading required at this time should be minimal provided that the residence 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 so that 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 memo or the referenced reports, please contact the undersigned. Respectfully submitted, SLADDEN ENGINEERING Brett L. Anderson Principal Engineer Letter/ra Copies BRETf L. ANDERSON� �i No. C45339i ni rG CIVI_ ENGINEERING hn 4/West Coast Builders, Inc. Madden F.nQineerinQ 5V9_ (9 /t l 19 -as-- 2Hq 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. Yes - No Crlterlon ❑ 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. 104 ❑ 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 required corrections. Siadden Engineering 45090 Golf Center Parkway, Suite F, Indio, CA 92201 (760) 863-0713 6782 Stanton Avenue, Suite C, Buena Park, CA 90621 (714) 523-0952 450 Egan Avenue, Beaumont, CA 92223 (951) 845-7743 800 E. Florida Avenue, Hemet, CA 92543 (951) 766.8777 www.Sladdenengin cering. com June 27, 2019 West Coast Builders, Inc. 78005 Wildcat Drive, Suite 104 Palm Desert, California 92211 Project: Proposed Custom Residence 57330 Peninsula Lane The Peninsula @ PGA West La Quinta, California Subject: Ref: Foundation Plan Review Project No. 544-19181 19-06-309 FC;I, OF LA QUINTA UILDING DIVISION 7jq�;—� REVIEWED FOR CODE C NIPLIANCE Geotechnical Update prepared by Sladden Engineering dated May 30, 2019; Project No. 544-19181, Report No.19-05-249 In accordance with your request, we have reviewed the Foundation Plans and Details prepared by West Coast Builders, Inc. for the proposed custom residence to be constructed at 57330 Peninsula Lane 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 geoted-mical 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 Brett L. Anderson Principal Engineer Letter/nh Copies: 4 / Addressee �0 PROtt. rp AN E 4 r rx o. 0 spas c Sladden Engineering ivitvlv.Sladdettengineerittg. cons Fil Sladden 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 May 30, 2019 Project No. 544-19181 19-05-249 West Coast Builders, Inc. 78005 Wildcat Drive, Suite 104 Palm Desert, California 92211 Project: Proposed Custom Residence 57330 Peninsula Lane PGA West — The Peninsula La Quinta, California 'DES F 6l0pg�7.yF'A�.. BUILDING DIVISION REVIEWED FOR CODE, COMPLIANCE r;�Qjq "' if Subject: Geotechnical Update Ref: Geotechnical Engineering report prepared by Buena Engineers, Inc. dated April 17, 1986; Project No. B-14413-P3, Report No. 86-4-209 Geotechnical Update report prepared by Sladden Engineering dated July 8, 2002; Project No. 544-2125 Report of Observations and Testing During Fine Grading prepared by Sladden Engineering dated March 17, 1999; Project No. 522-8096R In accordance with your request, we have reviewed the referenced geotechnical reports as they relate to the design and construction of the proposed custom residence. The project site is located at 57330 Peninsula Lane within the PGA West development in the City of La Quinta, California. It is our understanding that the proposed residential structure will be of relatively lightweight wood -frame construction and will be supported by conventional shallow spread footings and concrete slabs on grade. Based upon our report review, our previous experience on the site and our understanding of the proposed construction, it is our opinion that the structural values recommended in the previous geotechnical reports remain applicable for use in foundation design. Conventional shallow spread footings should be supported by 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 may be designed utilizing allowable bearing pressures of 1800 psf and 2000 psf, respectively. Increases in allowable bearing pressures may be realized with increased footing size. Allowable increases of 200 psf for each additional 1 foot of width and 250 psf for each additional 6 inches of depth may be utilized, if desired. The maximum allowable bearing pressure should be 2500 psf. The recommended allowable bearing pressures may be increased by one-third when considering wind and seismic loading. J 0a .V'0d May 30, 2019 -2- Project No. 544-19181 19-05-249 Resistance to lateral loads can be provided by a combination of friction acting at the base of the slabs or foundations and passive earth pressure along the sides of the foundations. A coefficient of friction of 0.45 between soil and concrete may be used with dead load forces only. A passive earth pressure of 300 pounds per square foot, per foot of depth, may be used for the sides of footings that are placed against properly compacted native soil. 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 18 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 cannot 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 2016 CBC or ASCE7. According to the 2016 CBC, Site Class D may be used to estimate design seismic loading for the proposed structures. This assumption should be verified by the project structural engineer. The 2016 CBC Seismic Design Parameters are summarized below. Occupancy Category (Table 1604.5): I/II/111 Site Class (Table 1613.5.5): D Ss (Figure 1613.5.1: 1.500g S1 (Figure 1613.5.1: 0.609g Fa (Table 1613.5.3(1)): 1.0 Fv (Table 1613.5.3(2)): 1.5 Sms (Equation 16-36 {Fa X Ss}):1.500g Sm1 (Equation 16-37 {Fv X S1}): 0.913g SDS (Equation 16-38 12/3 X Sms)):1.00Og SD1(Equation 16-39 {2/3 X Sm1}): 0.609g Seismic Design Category: D Sladden Engineering May 30, 2019 -3- Project No. 544-19181 19-05-249 Because the lot has been previously graded, the remedial grading required at this time should be minimal provided that the residence 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 so that 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 memo or the referenced reports, please contact the undersigned. Respectfully submitted, SLADDEN ENGINEERING Brett L. Anderson Principal Engineer Letter/ra trr B R ETT L. CO E. ANDERSON No. C45389 iu m CIVIL LZ) ENGINEERING *) Copies: 4/West Coast Builders, Inc. Madden Engineering !'may-f9«l 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 Quanta 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) no or, (b) the criterion is considered insignificant and explicitly so stated. Yes . No Criterion ® Foundation criteria based upon bearing capacity of natural or compacted soil. l3 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. Ql ® Foundation criteria to mitigate the effects of varying soil strength- 0 Foundation criteria to mitigate expected total and differential settlement. Any "No" answers to the above checklist should be noted as specific required corrections. CCSp9 ) 4 CIVIL j' I= INEERING t�