The URL can be used to link to this page

Home My WebLink AboutCT 05-10; POINSETTIA PROPERTY; SECOND SUPPLEMENTAL GEOTECHNICAL RETAINING WALL DESIGN RECOMMENDATIONS; 2011-02-15Earth Strata, Geotechnical, Environmental and Materials Testing Consultants I BETTER PEOPLE • BETTER SERVICE • BETTER RESULTS February 15, 2011 Project No. 10707-1C Mr. Walter Miller K. HOVNANIAN HOMES 1500 South Haven Avenue, Suite 100 Ontario, CA 91761 Subject: Second Supplemental Geotechnical Retaining Wall Design Recommendations, The Tides Development, Located on the Southwest Corner of Poinsettia Lane and Lowder Lane, City of Carlsbad, San Diego County, California Pursuant to your request, Earth-Strata has provided supplemental retaining wall design recommendations for the retaining walls utilizing the regional standards. The following recommendations may be utilized for the proposed C-i, C-4, and C-6 retaining walls planned at the subject property, as indicated on the grading plan Sheet Nos. 4, 5, and 10. RETAINING WALLS Active Earth Pressures Foundations may be designed in accordance with the recommendations provided above and within the referenced report. The following table provides the minimum recommended equivalent fluid pressure for design of retaining walls a maximum of 6.5 feet high, per the enclosed calculation sheet. The active earth pressure should be used for design of unrestrained retaining walls, which are free to tilt slightly. & MINIMUM STATIC EQUIVALENT FLUID PRESSURES (pcI) PRESSURE TYPE BACKSLOPE CONDITION 2:1 (h:v) BACKSLOPE Active Earth Pressure I 36 The retaining wall parameters provided do not account for hydrostatic pressure behind the retaining walls. Therefore, the subdrain system is a very important part of the design. All retaining walls should be designed to resist surcharge loads imposed by other nearby walls, structures, or vehicles should be added to the above earth pressures, if the additional loads are being applied within a 1:1 plane projected up from the heel of the retaining wall footing. As a way of minimizing surcharge loads and the settlement potential of nearby buildings, the footings for the building can be deepened below the 1:1 plane projected up from the heel of the retaining wall footing. EARTH- STRATA, INC. 26047 JEFFERSON AVENUE, SUITE C, MURRIETA,CA 92562 OFFICE (951) 461-4028 • FAX (951) 461-4058 - WWW.EART STRATA.COM BE-i 1 ER PEC)PL I- - BEl....I ER SERVICE - BE ii ER RESULIS I I The opportunity to be of service is appreciated. Should you have any questions or require further clarification, please notify our office at your earliest convenience. Respectfully submitted, lEA RT1HL=STRATA\, ]INC. Chad E. Welke, PG, CEG, PE Principal Geologist/Engineer CW/am QC' " ` NO. C63712 * EXP. 0-30- I ( 1* OF Attachments: Retaining Wall Calculation Sheet No.4 (Rear of Text) APPENDIX A References Distribution: (1) Addressee (4) Craig Kahlen, Rick Engineering Project No. 10707-10C 2 February 15, 2011 RETAINING WALL JN: 10707-IA CONSULT: & I PEOPLE. PROJECT: Khov/Carlsbad CALCULATION SHEET# 4 CALCULATE THE DESIGN MINIMUM EQUIVALENT FLUID PRESSURE (EFP) FOR PROPOSED RETAINING WALLS. THE WALL HEIGHT AND BACKSLOPE AND SURCHARGE CONDITIONS ARE LISTED BELOW. ASSUME THE BACKFILL IS SATURATED WITH NO EXCESS HYDROSTATIC PRESSURE. USE THE MONONOBE-OKABE METHOD FOR SEISMIC FORCES. CALCULATION PARAMETERS EARTH MATERIAL: Compacted Fill - Silty Sand WALL HEIGHT 6.5 feet SHEAR DIAGRAM: I BACKSLOPE ANGLE: 27 degrees COHESION: 331 psf SURCHARGE: 0 pounds PHI ANGLE: 28 degrees SURCHARGE TYPE: U Uniform DENSITY 130 pcf INITIAL FAILURE ANGLE: 35 degrees SAFETY FACTOR: 1.5 FINAL FAILURE ANGLE: 70 degrees WALL FRICTION 0 degrees INITIAL TENSION CRACK: 5 feet CD (C/FS): 220.7 psf FINAL TENSION CRACK: 100 feet PHID = ATAN(TAN(PHI)/FS) = 19.5 degrees HORIZONTAL PSEUDO STATIC SEISMIC COEFFICIENT (kh) 0 %g VERTICAL PSEUDO STATIC SEISMIC COEFFICIENT (ku) 0 %g CALCULATED RESULTS CRITICAL FAILURE ANGLE 46 degrees AREA OF TRIAL FAILURE WEDGE 25.9 square feet TOTAL EXTERNAL SURCHARGE 0.0 pounds WEIGHT OF TRIAL FAILURE WEDGE 3370.2 pounds NUMBER OF TRIAL WEDGES ANALYZED 3456 trials LENGTH OF FAILURE PLANE 7.2 feet DEPTH OF TENSION CRACK 3.9 feet HORIZONTAL DISTANCE TO UPSLOPE TENSION CRACK 5.0 feet CALCULATED HORIZONTAL THRUST ON WALL 6.5 pounds CALCULATED EQUIVALENT FLUID PRESSURE 0.3 pcf DESIGN EQUIVALENT FLUID PRESSURE 36.0 pcf THE CALCULATION INDICATES THAT THE PROPOSED RETAINING WALLS MAY BE DESIGNED FOR AN EQUIVALENT FLUID PRESSURE OF 36 POUNDS PER CUBIC FOOT. APPENDIX A REFERENCES APPENDIX A References Earth-Strata, Inc., 2010, Interpretive Report for Infiltration System, Proposed 29-Lot Residential Development, Located on the Southwest Corner of Poinsettia Lane and Lowder Lane City of Carlsbad, San Diego County, California, dated May 6. ________• 2010a, Preliminary Geotechnical Interpretive Report, Proposed 29-Lot Residential Development, Located on the Southwest Corner of Poinsettia Lane and Lowder Lane City of Carlsbad, San Diego County, California, dated May 11. ________• 2010b, Geotechnical Review of Draft Retaining Wall Alternative Analysis Report, Proposed 29-Lot Residential Development, Located on the Southwest Corner of Poinsettia Lane and Lowder Lane City of Carlsbad, San Diego County, California, dated May 25. 2010, Preliminary Turf Block Recommendation Letter, Proposed Residential Development, Located on the Southwest Corner of Poinsettia Lane and Lowder Lane, City of Carlsbad, San Diego County, California, dated September 14. 2010, Geotechnical Review of Foundation Plans for the Proposed 25-Lot Residential Development, Located on the Southwest Corner of Poinsettia Lane and Pasceo Del Norte, City of Carlsbad, San Diego County, California, dated October 20. ________• 2010, Supplemental Geotechnical Retaining Wall Design Recommendations, Proposed Poinsettia Residential Development, Located on the Southwest Corner of Poinsettia Lane and Lowder Lane City of Carlsbad, San Diego County, California, dated October 20. '2010, Update Geotechnical Retaining Wall Design Recommendations, Proposed La Marea Residential Development, Located on the Southwest Corner of Poinsettia Lane and Lowder Lane City of Carlsbad, San Diego County, California, dated November 11. ________• 2010, Geotechnical Evaluation of Storm Water Management for the Proposed 25-Lot Residential Development, Located on the Southwest Corner of Poinsettia Lane and Pasceo Del Norte, City of Carlsbad, San Diego County, California, dated November 11. _______• 2011, Revised Geotechnical Evaluation of Storm Water Management and Recommendations for Side Yard Drainage for the Proposed 31-Lot Residential Development, Located on the Southwest Corner of Poinsettia Lane and Pasceo Del Norte, City of Carlsbad, San Diego County, California, January 25. Lawson and Associates, Inc., 2005, Preliminary Geotechnical Investigation Report, Proposed 29-Lot Residential Development, Southwest Corner of Poinsettia Lane and Paseo Del Norte, City of Carlsbad, California, dated February 24.