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BPOL2018-0047 Geotechnical UpdateI I � V S 31 Sladden Engineering 45090 Golf Center Parkway, Suite F, Indio, CA 92201 (760) 8634M3 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 May 26, 2016 Project No. 544-16138 16-05 212 Mr. Bob Safai c/o Hayer Architecture, Inc. 445 Marine View Avenue, Suite 280 Del Mar, California 92014 Subject: Geotechnical Update Project: Proposed Custom Residence 81-454 Amundson Avenue The Madison Club -- Lot 19B La Quinta, California Ref: Geotechnical Investigation Report prepared by Sladden Engineering dated January 28, 2005; Project No. 544-4810, Report No. 05-01-101 Report of Testing and Observation During Rough Grading prepared by Sudden Engineering dated March 2, 2006; Project No. 522-4810; Report No. 05-M-120 As requested, we have reviewed the above referenced geotechnical reports as they relate to the design and construction of the proposed custom residence to be constructed on the site located at 81-454 Amundson Avenue within the Madison Club 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. The subject lot was previously graded during the rough grading of the Madison Club project site. The rough grading included over -excavation and recompaction of the native surface soil along with the placement of engineered Fill material to construct the building pads. The site grading is summarized in the referenced report of Testing and Observation During Rough Grading along with the compaction test results. Because the lot has been previously rough graded, the remedial grading required at this tin,_e should be minimal provided that the building area that falls within the previously assumed building envelope. Tne building areas should be cleared of surface vegetation, scari$ed a —a 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 Ieast 90 percent relative compaction. Sladden Engineering wwty. Sladdenengineering. com *31 May 26, 2016 2- Project No. 544-16138 16-05-212 The referenced reports include recommendations pertaining to the construction of residential structure foundations. The previous reports also address the potential for liquefaction, subsidence and differential settlement. Based upon our review of the referenced reports, it is our opinion that the structural values included in these reports remain applicable for the design and construction of the proposed residential structure foundations. The allowable bearing pressures recommended in the referenced Geotechnical Investigation report 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 I 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 and passive resistance along the sides of the footings. A friction coefficient of 0.48 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 033 times the normal dead load forces. The bearing soil is generally non -expansive and falls within the "very low" expansion category in accordance with the 2013 (CBC) classification criteria. Pertinent 2013 CBC Seismic Design parameters are summarized on the following page. Sladden has reviewed the 2013 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 2013 CBC or ASCEf. 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):1/11/11I Site Class (Table 1613.32):D Ss (Figure 1613.3.1):1.516g Si (Figure 1613.3.1): 0.711g Fa (Table 16133.3(1)):1.0 Fv (Table 1613.5.3(2)):1.5 Sms (Equation 16-37 tFa X 5s)): 1.516g Smi (Equation 16-38 (Fv X S1]):1.066g SDs (Equation 16-39 f2/3 X Sms)):1.011g SDI (Equation 16-40 f 2/3 X Sm7 j): 0.711g Seismic Design Category: D Sladden Engineering www.Sladdeneugineering. com May 26, 2016 -3- Project No. 544-16138 16-05-212 We appreciate the opportunity to provide service to you on this project. If you have any questions regarding this Ietter or the referenced reports, please contact the undersigned. Respectfully submitted, SLADDEN ENGINEERING Brett L. Anderson J a�r"C�� '� Principal Engineer pe—IrL "E s 1; C4 ; SERfc)b N°� � `s;:s EYp.9/�0116 I9 C1VIL t'ft Copies: Q Mr. Bob Safai �� ENGtN RI 1 CAL Sladden Engineering www.Sladdenengineering.cofn 1. 1 ► C La Quinta 14.763 06/17/Z¢ Please verify that soils reports contain all of the above information. In addition, to assur, 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 Geotechrdeal 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 Criterion ❑ Foundation criteria based upon bearing capacity of natural or compacted soft_ ❑ Foundation criteria to mitigate the effects of expansive soils. ❑ Foundation criteria based upon bearingCapacity PacitY of natural or compacted soil. ❑ Foundation criteria to mitigate the effects of liquefaction. ❑ Foundation criteria to mitigate the effects of seismical! induced dential y settlement. ❑ Foundation criteria to mitigate the 9 effects of song -team differential went. ❑ 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 speck required corrections. 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 (7I4) 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 June 6, 2016 Project No. 544-16138 16-06-223 Mr. Bob Safai c/o Hayer Architecture, Inc. 445 Marine View Avenue, Suite 280 Del Mar, California 92014 Project: Proposed Custom Residence 81-454 Amundson Avenue The Madison Club — Lot 19B La Quinta, California Subject: Soluble Sulfate Content Ref: Geotechnical Investigation Report prepared by Sladden Engineering dated January 28, 2005; Project No. 544-4810, Report No. 05-01-101 Report of Testing and Observation During Rough Grading prepared by Sladden Engineering dated March 2, 2006; Project No. 522-4810; Report No. 06-02-120 As requested, we have reviewed the geotechnical update report prepared for the subject property located at 81-454 Amundson Avenue, Lot 19B located within the Madison Club residential development with respect to soluble sulfate content as it relates to selecting appropriate concrete mix designs. Laboratory testing indicated soluble sulfate content of 2400 ppm (024 percent) that corresponds with the "severe" exposure category in accordance with Table 3 of ACI 318-08 Chapter 9. In accordance with ACI 3I8-08, special sulfate resistant concrete nix designs will be required for structural concrete on this project Structural concrete in contact with soil should have a minimum compressive strength of 4500 psi and maximum water/cement content of 0.45_ A copy of the laboratory test results is attached. If you have questions regarding this letter or the referenced report, please contact the undersigned. Respectfully submitted, SLADDEN ENGINEERIN Brett L. Anderson 1 AMID S s Principal Engineer No. Cup=J9 rT U ExR• 9/30116 h ctvu- Letter/clb " \-;r ENG111rGP1NG o-£, Copies: 4 / Mr. Bob Safaip- , d V Sladden Engineering 6782 Stanton Ave., Suite A. Buena Park, CA 90621 (714) 523-0952 Fax (714) 523-1369 45090 Golf Center Pkwy, Suite F, Indio, CA 92201 (760) 863-0713 Fax (760) 863-0847 450 Egan Avenue, Beaumont, CA 92223 (951) 845-7743 Fax (951) 845-8863 Date: June 6, 2016 Account No.: 544-16138 Customer: Mr. Bob Safai c/o Hayer Architecture, Inc Location: Amundson Way, Lot 19B, La Quinta Analytical Report Sulfate Series Soluble Sulfates Soluble Chloride per CA 417 per CA 422 ppm ppm 2400 •tl Sulfate 544-16138 060616 -TABLE I q-A-2—RE0ilIREMEfM FOR SPEC1kL EXPOSlJRE CONDCi10f4S- - MA7�ZMUhi • - f'n ,HOR�� AHL) . WATER-t0AE IiTi ?iG i MtLT[7iLALS' RAk -RY= ; :t2G7t�}Vc�Gff� - kmfiew+'tl4MHCRETE6 EXPOSURE COHOMOH AGGREGATE COR = x 0 nogs4ar UPS Con4retc intended to have low permeability when exposed to water 0 -50 J Concrete exposed to'frrczing and thawing in a moist condition or to deicing chemicals 0-45 4,500 For corrosion projection for reinfacred concrete exposed to chlorides fmm deicing ch&rnirals, salts or brackish wares, orsprayfmm thesc"soumes 0-40 5,OM TABLE TB-A-3•—REQUIREMEKiS:FC)14 CONCf3ETE EXFOSEO TO SULFATE-00WrAJNIHd-SOUM0NS _ r ORMAL-W 3GNl =AGGRSGATE ActMEGATE = CONCRETE n;lYatcf- - CatsrstGttauz _ f" ttm;nst- �� • - - -• WATER- SOLUBLE htataaiets-_Rat3a; bq=. SULFATE ( tI' g&IH ttc4rsut d r pJt SULFATE E P AGE BY SULFATE [SO4)IN t¢yrcgEta x a --S9TaritPa EXPOSURE WEIGHT , WATER, ppft CEMERTTYPE Corrtetes Ilegligibie 0 00-0.1Q 0-150 - — —. — Modcratc2• 0-10-Q20 L50-1S00 If.IP(MS7,7S W-0- S,£rMJ CMS) _ Sevcre 0.20-7-00 E,50040,000 -V 0.45 _ 41%0 troy severe Over 200 Over 10,000 V plus A45 4.5 pozaolan3 IA Iowcr water-ccmrntitious marcriaLs ratio orhighcrs4=gth rssa7-� benquimd for law permca-b igroriarpcatsea� against eocrorion'of cmbcddcd items or fre�rtg and rhawiag [i'abl- 2Scawater_ _ ?Fozsotan that has been dctcrrniocd by test orservice romrd to impmvesulfate rmdsbnce whca rid inconmcm coo - ram ring TI epc V rcmcnL