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Home My WebLink AboutSDP 16-13; OAK VETERANS HOUSING; RESPONSE TO REVIEW COMMENTS PROPOSED THREE-STORY APARTMENT BUILDING; 2020-06-05I AA GEOTECHNICAL Ll Me I MATERIALS NOVA SPECIAL INSPECTION Affirmed Housing Group CIO Marie Allen 13520 North Evening Creek Drive San Diego, CA 92128 Attention: Ms. Allen DVBE. SBE. SDVOSB. SLBE June 5, 2020 NOVA Project No. 3019096 (via email; marie@affirmedhousing.com) Subject: Response to Review Comments E IVrED Proposed Three-Story Apartment Building 965 - 967 Oak Avenue, Carlsbad, California JUL 20 2020 LAND DEVELOPMENT Rfrtinra ENGINEERING CWE 2016. Report of Preliminary Geotechnical Investigation, Affirmed Housing, 965-967 Oak Avenue, Carlsbad, California, Christian Wheeler Engineering, June 3, 2016. NOVA 2020a. Update Geotechnical Engineering Report, Proposed Three-Story Apartment Building, 965- 967 Oak Avenue, Carlsbad, California, NOVA Services, January 17, 2020. NOVA 2020b. Response to Review Comments, Proposed Three-Stop,' Apartment Building, 965-967 Oak Avenue, Carlsbad, California, NOVA Services, April 30, 2020. KLE 2020. Grading Plans For: Oak Veterans Housing, 365— 367 Oak Avenue, Kettler Leweck Engineering, June 5, 2020. The intent of this letter is to respond to comments by the City of Carlsbad third-party review, regarding its review of the above-referenced geotechnical report. The comments were prepared by Hetherington Engineering, Inc. under cover Third-Party Geotechnical Review (Second), May 20, 2020 and are referenced herein as 'Hetherington 2020.' NOVA Services, Inc. (NOVA) is retained by Affirmed Housing Group as Geotechnical Engineer- of-Record (GEOR) for the project. REVIEW COMMENTS AND RESPONSES The following text reproduces comments in Hetherington 2020 regarding geotechnical-related design for the above-referenced project. Comments from Hetherington 2020 are reproduced below in italics, following which a response is provided by NOVA. Comment 1. The 2019 California Building Code (CBC) and ASCE 7-16 are the governing codes. The Consultant should confirm that the geotechnical recommendations are consistent with these documents. Response. NOVA understands that this project was initially submitted prior to January 1, 2020 and the initiation of the new governing codes. NOVA understands the project qualifies for 2016 CBC and ASCE 7-10. 4373 Viewridge Avenue, Suite B www.usa-nova.com 944 Calle Amanecer, Suite F San Diego, CA 92123 San Clemente, CA 92673 P: 858.292.7575 P: 949.388.7710 ii NOVA Response to Review Comments Proposed Three-Story Apartment Building 965-967 Oak Avenue, Carlsbad, CA NOVA Project No. 3019096 June 5, 2020 Comment 2. The Consultant should review the project grading and foundation plans, provide any additional geotechnical recommendations considered necessary, and confirm that the plans have been prepared in accordance with the geotechnical recommendations. Response Acknowledged. NOVA has reviewed the referenced grading plan by Kettler Leweck. The geotechnical recommendations have been properly implemented into the grading plan. NOVA will review and sign/stamp additional plans or provide a plan review letter when additional plans have been received. Comment 3. The consultant should provide an updated geotechnical map/plot plan utilizing the latest grading plan for the project to clearly show (at a minimum) a) existing site topography, b) proposed structures/improvements, c) proposed finished grades, d) locations of the subsurface exploration, e) geologic contacts, and 0 remedial grading limits, etc. Response. The requested geotechnical map has been revised to reflect the latest grading plan and are attached hereto as Plate 1. Comment 4. References 3 and 4 refer to a Christian Wheeler Engineering geotechnical investigation report, dated June 2, 2016. The Christian Wheeler Engineering geotechnical investigation reported submitted is dated August 4, 2016 (Reference 2). The consultant should clarify which Christian Wheeler Engineering report is intended and confirm that the conclusions and recommendations remain applicable Response. Noted. The content of the Christian Wheeler Engineering report dated April 20, 2016 was limited to providing preliminary recommendations. NOVA now understands that this report was not submitted. NOVA will remove future references to the Christian Wheeler Engineering report dated April 20, 2016. Comment 5. The Consultant should address whether the site is considered a Wear Fault Site" in accordance with the 2019 CBC, section 1803.5.12. Response. The site is not considered a "Near Fault Site" in accordance with 2019 CBC, Section 1803.5.12. In accordance with 2019 CBC, Section 1803.5.12, the site is not considered subject to liquefaction and does not have retaining walls over 6 feet. Comment 6. The consultant should provide the site Risk Category and Seismic Design Category consistent with the 2019 CBC. Response. NOVA understands that this project was initially submitted prior to January 1, 2020 and the initiation of the new governing codes. NOVA understands the project qualifies for 2016 CBC and ASCE 7-10. The site should be considered Risk Category II and Seismic Design Category C. 2 A NOVA Response to Review Comments Proposed Three-Story Apartment Building 965-967 Oak Avenue, Carlsbad, CA NOVA Project No. 3019096 June 5, 2020 Comment 7. The consultant should provide a detailed description of proposed site grading, structures/improvements, etc. Response. A detailed description of proposed site grading, structures/improvements, etc. is detailed in the referenced geotechnical report (CWE 2016a) and remains valid unless amended in the referenced update geotechnical engineering report (NOVA 2020a.). Remedial grading recommendations are reiterated below: "OBSERVATION OF GRADING: Continuous observation by the Geotechnical Consultant is essential during the grading operation to confirm conditions anticipated by our investigation, to allow adjustments in design criteria to reflect actual field conditions exposed, and to determine that the grading proceeds in general accordance with the recommendations contained herein. CLEARING AND GRUBBING: Site preparation should begin with the demolition of existing improvements. The resulting debris and any existing vegetation and other deleterious materials in areas to receive proposed improvements or new fill soils should be removed from the site. SITE PREPARATION: It is recommended that existing potentially compressible topsoil and weathered old paralic deposits underlying proposed structures, associated improvements, and new fills should be removed in their entirety. Based on our findings, the maximum anticipated removal depth is 4 feet below existing grade. Deeper removals may be necessary in areas of the site not investigated or due to unforeseen conditions. Lateral removals limits should extend at least 5 feet from the perimeter of the structures, any settlement sensitive improvements, and new fills or equal to removal depth, whichever is more. No removals are recommended beyond property lines. All excavated areas should be approved by the geotechnical engineer or his representative prior to replacing any of the excavated soils. The excavated materials can be replaced as properly compacted fill in accordance with the recommendations presented in the "Compaction and Method of Filling" section of this report. PROCESSING OF FILL AREAS: Prior to placing any new fill soils or constructing any new improvements in areas that have been cleaned out to receive fill, the exposed soils should be scarified to a depth of 12 inches, watered thoroughly, and compacted to at least 90 percent relative compaction. COMPACTION AND METHOD OF FILLING: In general, all structural fill placed at the site should be compacted to a relative compaction of at least 90 percent of its maximum laboratory dry density as determined by ASTM Laboratory Test D1557. Fills should be placed at or slightly above optimum moisture content, in lifts six to eight inches thick, Am NOVA Response to Review Comments Proposed Three-Story Apartment Building 965-967 Oak Avenue, Carlsbad, CA NOVA Project No. 3019096 June 5, 2020 with each lift compacted by mechanical means. Fills should consist of approved earth material, free of trash or debris, roots, vegetation, or other materials determined to be unsuitable by the Geotechnical Consultant. Fill material should be free of rocks or lumps of soil in excess of three inches in maximum dimension. Utility trench backfill within five feet of the proposed structure and beneath all concrete flatwork or pavements should be compacted to a minimum of 90 percent of its maximum dry density." Comment 8. The consultant should provide grading and/or foundation recommendations for property line fences. Response. Remedial grading recommendations for property line fences should include the removal of 2 feet of soil from proposed grade or I below the bottom of foundation design elevation, whichever is deeper. Laterally, remedial grading should extend 2 feet outward or to property lines. If the side wall excavations for the adjacent property are probed to be then deeper excavations may be required and will be determined during construction. Comment 9. The consultant should provide a statement regarding the impact of the proposed grading and construction on adjacent properties and improvements. Response. Based upon our review of the referenced project plans, it is NOVA's opinion that the proposed improvements will not adversely impact adjoining sites or public improvements provided the geotechnical recommendations are appropriately implemented. Comment 10. The consultant should provide geotechnical recommendations for temporary excavations. Response. Based on our review of the referenced project plans, the proposed development can be constructed utilizing the recommended temporary cut slope excavations consisting of a 4 feet vertical excavation with a 1:1 (horizontal:vertical) upper cut gradient. Comment 11. The consultant should provide a list of recommended observation and testing during site grading and construction. Response. Anticipated Geotechnical Services During Site Development include, but are not necessarily limited to: > Review of remedial grading excavations. > Observation and in-place soil density testing during fill placement. ) Review of all foundation excavations. > Review of backcuts (if any). > Testing of utility trench backfill. 4 Plate 1. Subsurface Investigation Map Response to Review Comments Proposed Three-Story Apartment Building 965-967 Oak Avenue, Carlsbad, CA NOVA. NOVA Project No. 3019096 June 5, 2020 > Review and/or testing of subgrade for hardscape. ) Materials testing (concrete, steel, asphalt, wood, shear walls, etc.) CLOSURE NOVA appreciates the opportunity to be of continued service to Affirmed Housing Group for the subject project. Should you have any questions regarding this letter or other matters, please contact the undersigned at (949) 388-7710. Sincerely, NOVA Services, Inc. C84335 "'P.C,V,. OF C 5 Response to Review Comments Proposed Three-Story Apartment Building 965-967 Oak Avenue, Carlsbad, CA NOVA NOVA Project No. 3019096 June 5, 2020 ATTACHMENT I SUBSURFACE INVESTIGATION MAP