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Home My WebLink AboutCT 16-03; Beach Village Life 1 Mixed Use; GEOTECHNICAL REVIEW OF GRADING AND SHORING PLANS; 2018-10-11• RECORD COPY l0/11./,t O'-A / "'"'~ TPi SJ, Jnmal Date Geotechnical • Geologic • Coastal • Environmental 5741 Palmer Way • Carlsbad. California 92010 • (760) 438-3155 • FAX (760) 931 -0915 • www.geosoilsinc.com Beach Vi II age Life 1, LLC c/o Karnak Planning and Design 381 Christiansen Way Carlsbad, California 92008 October 11 , 2018 Attention: Mr. Robert Richardson W.O. 6942-A 1-SC RECEIVED OCT 11 2018 LAND DEVELOPMENT ENGINEERING Subject: Geotechnical Review of Grading and Shoring Plans, Planned Mixed-Use Hotel, Spa, and Condominiums, Christiansen Way, Carlsbad, San Diego County, California, Assessor's Parcel Number (APN) 203-173-02-00, City of Carlsbad Project No.: CT 16-03 Dear Mr. Richardson : In accordance with your request and authorization, GeoSoils, Inc. (GSI) is providing this summary letter of our geotechnical review of the grading and shoring plans respectively prepared by Spear and Associates, Inc. ([S&A], 2018 [see Appendix]) and Sun Structural Engineering, Inc. ([SSE], 2018) for the subject project. The purpose of our review was to evaluate if S&A (2018) and SSE (2018) have properly incorporated the recommendations contained herein and in the project geotechnical reports (GSI; 2015, 2016, 2017, 2018a, 2018b, and 2018c). The services GSI performed for this study included a review of the documents referenced in the Appendix and the preparation of this summary letter. Unless specifically superseded herein, the conclusions and recommendations contained in GSI (2015, 2016, 2017, 2018a, 2018b, and 2018c) are still considered valid and applicable, and should be appropriately implemented during project design and construction. It is our understanding that the City of Carlsbad is requiring that the void space between the face of the backcut and the backside of the shoring lagging boards be backfilled with 1 ½-sack sand-cement slurry rather than pea gravel. Th is backfill method is considered suitable from a geotechnical perspective provided that two (2) Mirafi G100W composite drain panels are installed back-to-back along the face of the backcut, near the center of each lagging bay. The drain panels should be oriented such that the filter fabric is exposed on the exteriors of the back-to-back panels. In addition, the drain panels' plastic core should be covered byfilterfabric on all sides. The minimum width of the drain panels should be 12 inches. The drain panels may be installed in 4-foot to 5-foot vertical lengths provided that the laps between panels are not less than 6 inches with the underlying laps positioned behind the overlying laps. The tops of the drain panels should be held down 6 inches below the finished exterior grade. The 1 ½-sack sand-cement slurry should be placed between the drain panels and the backside of the lagging boards. Similar to the drain panels, the slurry should also be held down 6 inches below the finished exterior grade or to a depth deemed acceptable for planting by the Project Landscape Architect. The vertical space between the exterior grade and the top of the slurry/top of the drain panels should be backfilled with very low expansive soils (expansion index < 20 and plasticity index < 14). Compaction efforts should be applied when backfilling the aforementioned vertical space to provide a relatively firm and non-yielding surface. Based on our review, S&A (2018) and SSE (2018) are in general accordance with the geotechnical recommendations provided herein and those contained in GSI (2015, 2016, 2017, 2018a, 2018b, and 2018c); and therefore, are approved from a geotechnical standpoint. Should any significant revisions be made to S&A (2018) and/or SSE (2018) following the issuance of this letter, the conclusions contained herein shall be considered invalid until the plan revisions have been reviewed and approved by this office. LIMITATIONS The conclusions and recommendations are professional opinions. These opinions have been derived in accordance with current standards of practice, and no warranty, either express or implied, is given. Standards of practice are subject to change with time. GSI assumes no responsibility or liability for work or testing performed by others, or their inaction; or work performed when GSI is not requested to be onsite, to evaluate if our recommendations have been properly implemented. Use of this report constitutes an agreement and consent by the user to all the limitations outlined above, notwithstanding any other agreements that may be in place. In addition, this report may be subject to review by the controlling authorities. Thus, this report brings to completion our scope of services for this portion of the project. Beach VIiiage Lile 1, LLC APN 203-173-02-00, Carlsbad File:e:\wp12\6900\6942a1 .gro GeoSoils, Inc. W.O. 6942-A1-SC October 11, 2018 Page 2 If you have any questions or comments regarding this letter, please do not hesitate to contact the undersigned. Ryan B. Boehmer Project Geologist RBB/JPF/ATG/jh Attachment: Appendix -References Distribution: (2) Addressee (wet signed, via US Mail and email) (1) Spear and Associates, Inc., Attention: Mr. Nick Dampf (via email) (1) Sun Structural Engineering, Inc., Attention: Mr. Changhua Sun (via email) Beach VIiiage Life 1, LLC APN 203-173-02-00, Carlsbad File:e:\wp12\6900\6942a1 .gro GeoSoils, Inc. W.O. 6942-A1-SC October 11, 2018 Page 3 • APPENDIX REFERENCES GeoSoils, Inc., 2018a, Geotechnical response to City of Carlsbad third-party plan check and Engineering Department review comments, planned mixed-use hotel, spa, and condominiums, Christiansen Way, Carlsbad, San Diego County, California, Assessor's Parcel Number (APN) 203-173-02-00, City of Carlsbad Project No.: CT 16-03, W.O. 6942-A1-SC, dated May 30. __ , 2018b, Geotechnical update evaluation, planned mixed-use hotel, spa, and condominiums, Christiansen Way, Carlsbad, San Diego County, California, Assessor's Parcel Number (APN) 203-173-02-00, W.O. 6942-A1-SC, dated February 15. __ , 2018c, Revised cast-in-drilled-hole (CIDH) pile recommendations, planned mixed-use hotel, spa, and condominiums, Christiansen Way, Carlsbad, San Diego County, California, Assessor's Parcel Number (APN) 203-173-02-00, W.O. 6942-A1-SC, dated February 5. __ , 2017, Supplemental geotechnical recommendations, proposed mixed-use hotel, spa, and condominiums, Christiansen Way, Carlsbad, San Diego County, California, Assessor's Parcel Number (APN) 203-173-02-00, dated October 23. __ , 2016, Geotechnical response to City of Carlsbad Engineering Department plan check comments, Beach Village Life 1 Mixed Use, APN 203-173-02-00, Carlsbad, San Diego County, California, CT 16-03/RP 16-09/CDP16-16, W.O. 6942-A1-SC, dated June 20. __ , 2015, Preliminary geotechnical evaluation, APN 203-173-02-00, Carlsbad, San Diego County, California, W.O. 6942-A-SC, dated September 11. Spear and Associates, Inc., 2018, Precise grading plan for: Beach Village Life, 300 Christiansen Ave, 12 sheets, various scales, City of Carlsbad Project No.: CT 16-03, Drawing No.: 508-9A, plot dated October 11. Sun Structural Engineering, Inc., 2018, Shoring plans for: Beach Village Life, Christiansen Way, 6 sheets, various scales, plot dated September 26 GeoSoils, Inc.