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HomeMy WebLinkAboutCDP 09-11; GOETZ EMERGENCY SEAWALL; RESPONSE TO CITY AND THIRD PARTY REVIEW COMMENTS, EMERGENCY BLUFF RESTORATION 5323 AND 5327 CARLSBAD BOULEVARD; 2009-04-03,, • APR o ·, 2009 CITY OF CARLSBAD ENGINEERING DEPARTMENT DEVELOPMENT SERVICES DIVISION Geotechnical • Geologic • Coastal • Environmental 5741 Palmer Way • Carlsbad, California 92010 • (760) 438-3155 • FAX (760) 931-0915 City of Carlsbad 1635 Faraday Avenue Carlsbad, California 92008 April 3, 2009 Attention: Mr. Glen Van Peski, Senior Civil Engineer W.O. S5828-SC CDP 09-Jrf// Subject: Response to City and Third Party Review Comments, Emergency Bluff Restoration 5323 and 5327 Carlsbad Boulevard, Carlsbad, California. Reference: "Third Party Geotechnical Review of Proposed Restoration, Coastal Bluff Failure at 5323 and 5327 Carlsbad Boulevard, Carlsbad, California," Project No. 106560001, dated March 24, 2009, by Ninyo & Moore. Dear Mr. Van Peski At the request of Mr. Goetz and Mr. Sylver, GeoSoils Inc (GSI) is pleased to provide the following response to the referenced third party review by Ninyo & Moore and the draft review comments from Van Lynch, City of Carlsbad Planning Department. For ease of consideration, we are providing the review comments in bold, followed by our response. NINYO & MOORE COMMENTS Review Comment No. 1 Based on our background review and field observations, the geologic conditions at the project sire appear to be as described in the referenced documents. However, none of the documents in the submittal are signed or sealed by a California Engineering Geologist {CEG). Documentation, that is signed and sealed by a CEG, should be provided by the Consultant indicating that the geologic conditions are those that are assumed in the proposed bluff repair. Response to Review Comment No. 1 By signing this response, the undersigned California Engineering Geologist declares that the geologic conditions at the site reasonably represent the geologic conditions used for the restoration design and calculations ( ( Review Comment No. 2 A geotechnical evaluation report for the project indicating the subsurface exploration locations, boring and/or test pit logs, sampling locations and procedures, and laboratory testing was not included in the referenced documents. The submittal for bluff repair should include a formal, comprehensive geotechnical evaluation report for the project. Response to Review Comment No. 2 The site has been subject to several geotechnical evaluations in the past that supported the recent construction of the residences at 5323 and 5327 Carlsbad Boulevard. A list of these evaluations is provided at the end of this report and 2 copies of each will be provided with this response. In addition to these reports, GSI obtained soil samples in the face of the un-failed bluff, below the subject properties. A sample of the terrace deposits was taken at elevation of about +24 feet Mean Sea Level (MSL), and of the Santiago bedrock at elevation of about + 1 O feet MSL. Given the above-average amount of geologic and geotechnical data of the events tor the project site, it is our opinion that no additional subsurface exploration or soils sampling is necessary for the emergency bluff repairs. Review Comment No. 3 Based on our review of the Structural Calculations for Bluff Repair prepared by Randle {2009), the calculations were prepared in conformance with the results of the direct shear test data submitted by GSI {2009b)., however, the basis for applying an adhesion value of 1.66 ksf for tieback capacity and the Factor of Safety used in the calculations was not included. Response to Review Comment No. 3 The length shown on the plans are based on a 2,500 pounds per square foot (psf) skin friction. A value of 1.66 kips1i-a.s used in the wall calculations to account tor a 1.5 factor of safety. w Review Comment No. 4 In addition, the submittal should be based on slope stability analyses and indicate the Factor of Safety under the improved conditions for the project. We suggest that the results of the slope stability analysis be included in the geotechnical evaluation report, requested above. Response to Review Comment No. 4 A slope stability analysis is attached to this response. City of Carlsbad 5323 and 5327 Carlsbad Boulevard File:e:\wp12\5800\s5828.rtc GeoSoils, lne. W.O. S5828-SC April 3, 2009 Page2 ( I l Review Comment No. 5 A letter should be provided by GSI indicating that they have reviewed the structural calculations and plans for the bluff repair and that their geotechnical recommendations and design parameters have been properly incorporated into the design. Response to Review Comment No. 5 We have reviewed the calculations from a geotechnical viewpoint, and our recommendations have been properly incorporated into the design. Review Comment No. 6 Further, GSI should comment on type of backdrain(s) recommended for the wall. Response to Review Comment No. 6 Sheet 6 of 7 provides a wall drain detail. The actual backfill has yet to be finalized. Either a fabric wrapped gravel drain or a slurry will be used to back fill the wall. All the repair/restoration work shall be performed under our observation. Review Comment No. 7 The reviewed plans indicate that a five foot excavation should occur behind the wall. However, without supporting geotechnical data the recommended five foot excavation may not be adequate to remove the landslide materials behind the wall. The plans also indicate that gravel or slurry may be used for backfill behind the wall but no specifications for these materials are presented. Slurry backfill may not be compatible with the proposed drainage system. Response to Review Comment No. 7 The review comment is noted and will be addressed during the construction of the wall. CITY OF CARLSBAD COMMENTS Engineering: Review Engineering Comment No. 1 Prepare and submit a Storm Water Standards Questionnaire (SWQ) to determine storm water status of project. A copy of SWQ can be found on the City website or at the engineering services counter at 1635 Faraday Avenue. City of Carlsbad 5323 and 5327 Carlsbad Boulevard File:e:\wp12\5800\s5828.rtc GeoSoils, lne. W.O. S5828-SC April 3, 2009 Page3 ( \ ( Response to Review Engineering Comment No. 1 In progress. Review Engineering Comment No. 2 Prepare and s 1t a Project Threat Assessment Form (PT AF) according to City Engineerin andards. A copy of PTAF can be found on the City website or at the ng services counter at 1635 Faraday Avenue. Response to Review Engineering Comment No. 2 In progress. Planning and Engineering: Review Planning and Engineering Comment No. 1 ~d the project title (Goetz Emergency Seawall) to the top center of the first sheet of the exhibit. Response to Review Planning and Engineering Comment No. 1 OK Review Planning and Engineering Comment No. 2 ~~ the application number (CDP 09-07) to the upper right hand corner of the exhibits. Response to Review Planning and Engineering Comment No. 2 OK Review Planning and Engineering Comment No. 3 ~ the assessor's parcel numbers to the first sheet of the exhibit. Response to Review Planning and Engineering Comment No. 3 OK City of Carlsbad 5323 and 5327 Carlsbad Boulevard File:e:\wp12\5800\s5828.rtc GeoSoils, Ine. W.O. S5828-SC April 3, 2009 Page4 ( ( Review Planning and Engineering Comment No. 4 ve-omplete the Owner's/Developer's Certificate in the lower left corner of sheet 1. Include representatives of both properties. Response to Review Planning and Engineering Comment No. 4 OK Review Planning and Engineering Comment No. 5 ~d the recording information for the existing drainage easement. Response to Review Planning and Engineering Comment No. 5 OK Review Planning and Engineering Comment No. 6 ~d the recording information for the existing open space easement. Response to Review Planning and Engineering Comment No. 6 OK Review Planning and Engineering Comment No. 7 ~dd the recording information and identify the location of the existing public access easement. Response to Review Planning and Engineering Comment No. 7 OK Review Planning and Engineering Comment No. 8 ~ the proposed earthwork quantities including, cut, fill, import and or export as appropriate. Response to Review Planning and Engineering Comment No. 8 OK City of Carlsbad 5323 and 5327 Carlsbad Boulevard File:e:\wp12\5800\s5828.rtc GeoSoils, lne. W.O. S5828-SC April 3, 2009 Pages ( ( Review Planning and Engineering Comment No. 9 Special Condition Note #1 states that the wall will conform as closely to the natural contour of the bluff as possible. The plan view and cross sections of the wall on sheets 2, 4, and 5 show a nearly straight and vertical wall that does not conform to the natural contour of the bluff. Please revise either the note or the plan. Response to Review Planning and Engineering Comment No. 9 ~e note has been revised. Review Planning and Engineering Comment No. 1 o Special Condition Note # 4 states that all runoff from impervious areas will be collected and directed away from the bluff edge towards the street. Grading Plan 402-0A shows all runoff being collected at the existing grated storm drain inlet along the south boundary and then directed westerly to the bottom of the bluff. Please revise the note or show drainage facilities to comply with the note. Response to Review Planning and Engineering Comment No. 1 o /oK Review Planning and Engineering Comment No. 11 Revise Special Condition Note #7 to identify the location of the construction access. Please identify the location on the plan and add a detail if necessary. Resgonse to Review Planning and Engineering Comment No. 11 ~!ruction access will be from in front of the power plant to the north with approval from State Parks. Review Planning and Engineering Comment No. 12 Peer review of the exhibits and the concrete seawall stability calculations have not been completed. Additional comments and issues may be identified by that review and will be forwarded under separate cover. City of Carlsbad 5323 and 5327 Carlsbad Boulevard File:e:\wp12\5800\s5828.rtc GeoSoils, lne. W.O. S5828-SC April 3, 2009 Page 6 ( Review Planning and Engineering Comment No. 13 Address all other engineering redline comments as noted on the returned exhibits. Return the redlines with the re-submittal to facilitate continued staff review. Response to Review Planning and Engineering Comment No. 13 Not yet re:~i~~~~:,-,~ If you have ariy additional questions or comments, please contact the undersigned at (760) 438-3155. GeoSoils, Inc. JPF/DWS/jh Attachment: Appendix -Additional References Distribution: (2) Addressee City of Carlsbad 5323 and 5327 Carlsbad Boulevard File:e:\wp12\5800\s5828.rtc GeoSoils, lne. David W. Skelly Civil Engineer, RCE Lt\?J~i"'---·--- W.O. S5828-SC April 3, 2009 Page? , . ( ( APPENDIX ADDITIONAL REFERENCES Converse Consultants, Inc., 1984a, Supplemental geotechnical investigation, proposed coastal protection measures for the 2± acre coastal site, Carlsbad, California, Project No. 83-2299-02, dated September 20. __ , 1984b, Geotechnical investigation, proposed coastal protection measures for the Ecke site, Carlsbad, California, Project No. 83-02299-01, dated February 1. GeoSoils, Inc., 2008, Bluff collapse inspection, 5323 and 5327 Carlsbad Blvd, Carlsbad, W.O. S5828, dated December 24. ICG, Incorporated, 1991, Geotechnical investigation and bluff retreat study, Parcel No. 210-120-30, Carlsbad, California, Job No. 04-8529-001-00-00, Log No. 1-1418, dated March 28. Owen Engineering Group, 2001, Geotechnical review and update of applicable geology and geotechnical reports for 5323 Carlsbad Blvd. Carlsbad, CA, dated October 10. Southland Geotechnical Consultants, 1997 Geotechnical evaluation of coastal bluff property, vacant parcel south of 5305 Carlsbad Boulevard, Project No. 126G21, dated March 10. GeoSoils, lne.