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Home My WebLink AboutSDP 2024-0001; THE ROOSEVELT; RESPONSE TO REVIEW COMMENTS; 2025-09-196960 Flanders Drive ■ San Diego, California 92121-2974 ■ Telephone (858) 558-6900 ■ www.geoconinc.com Project No. G3112-52-01 September 19, 2025 Fabric Investments 2727 Roosevelt Street, Suite B Carlsbad, California 92008 Attention: Mr. Brandan Foote Subject: RESPONSE TO REVIEW COMMENTS (2nd GEOTECHNICAL REVIEW) THE ROOSEVELT MIXED USE 2621 ROOSEVELT STREET CARLSBAD, CALIFORNIA Dear Mr. Foote: We prepared this letter to address the referenced City of Carlsbad Geotechnical Report review comments for the development of the subject project. Pertinent plans and reports are listed in the List of References at the end of this letter. The pertinent review comments are listed herein with the responses immediately following. Comment 1:The lab test result of the on-site soil provided in the report indicates an Expansion Index of 0. However, Table 7.1 (Summary of Conclusions and Recommendations) and Table 7.8.1 (Minimum Concrete Slab-On-Grade Recommendations) along with other sections of the report indicate the use of soils with an Expansion Index of 50 or less are suitable for the proposed development. As soils with an Expansion Index over 20 are considered expansive and require mitigation in accordance with Sections 1803.5.3 and 1808.6 of the 2022 California Building Code, please clarify the recommendations that are being provided for the design of the foundation/floor slab of the proposed building to address soils with an EI between 20 and 50 and satisfy the requirements of Section 1808.6 of the 2022 California Building Code. Please provide the methods (1806.1 through 1806.4) and any geotechnical parameters (Effective Plasticity Index, etc.) that are being recommended by Geocon, Inc., to address expansive soils (for soils with an EI between 20 and 50) and satisfy the requirements of Section 1808.6 of the 2022 California Building Code for the proposed slab-on-ground construction; and provide a statement that the foundation system for the proposed structure will meet the requirements of Section 1808.6 of the 2022 California Building Code. Please provide the basis for all parameters provided.(repeat comment – As the report provides recommendations for the use of soils that are considered expansive per the 2022 California Building Code (EI greater than 20), please state the specific procedure GEOCON INCORPORATED CAL ■ E NV I RONMENTA L ■ MA T ER I A L S G E OT E CHN I The Roosevelt – Mixed Use Response to Review Comments Project No. G3112-52-01 - 2 - September 19, 2025 of Section 1808.6 of the 2022 CBC that is being applied for the foundation/slab on-ground recommendations for the proposed structure to accommodate an expansion index up to 50 (low) and satisfy the building code requirement and mitigate potential expansive soils. Please provide a statement that the geotechnical recommendations provided by the consultant in the geotechnical report satisfy the requirements of Section 1808.6 of the 2022 California Building Code. Response: As indicated in our referenced report, our foundation and slab-on-grade recommendations consider the anticipated soils that may be at ultimate grade and are typical industry standard recommendations that are intended to reduce the potential for cracking of slabs due to expansive soil, differential settlement of existing soil or soil with varying thicknesses. We do not consider the use of post- tensioned foundations necessary for the existing site conditions, assuming the recommendations provided in our report are incorporated into the design and construction of the project. Section 1808.6.2 of the CBC permits the structural engineer to analyze and design such slabs by other methods than the two referenced above. Comment 2:Please provide the Cal-OSHA Type Soil (A, B, or C) and associated temporary slope inclination (H:V) that the construction plans and contractors should adhere to during the design and construction of the development. (repeat comment – as the consultant has deferred to OSHA guidelines and the contractor for temporary slopes/backcuts in the “Response to Review Comments…” report, please provide the preliminary OSHA Type Soil (A, B, or C) based on the consultants subsurface exploration and geotechnical knowledge of the subject site that the construction plans and contractors should adhere to during the design and construction of the development.) Response: In general conformance with Occupation Safety and Health Act (OSHA) Trenching and Excavation Safety, the site soils may be considered Soil Type B based on the materials encountered during our referenced geotechnical investigation. The soil type should be revised to Soil Type C if seepage is encountered along the face of excavations. However, in accordance with OSHA, it is the responsibility of the contractor and their competent person to determine the soil type during construction to ensure all excavations, temporary slopes and trenches are properly constructed and maintained in accordance with applicable OSHA guidelines, in order to maintain safety and the stability of the excavations and adjacent improvements. The Soil Type should be adjusted as necessary based on the conditions observed in the field. Comment 3:Please clarify the recommendations for temporary cuts anticipated for this specific project for the proposed remedial grading and/or foundation excavations along the property boundaries. Please provide specific recommendations for excavations as necessary to prevent adverse impact to the existing adjacent off-site property and structures/improvements with respect to temporary cuts associated with the proposed grading/construction along the property boundaries.(repeat comment) ~GEOCON The Roosevelt – Mixed Use Response to Review Comments Project No. G3112-52-01 - 3 - September 19, 2025 Response: A slot-cutting grading technique may be required where excavations are planned adjacent to existing structures and improvements. Care should be taken by the grading contractor so that impact to existing improvements and buildings does not occur during slot-cut excavations. This may require reduce slot cut lengths if loose or otherwise unstable soil is encountered. The contractor should be aware that there is an inherent risk to slot-cutting as movement of near vertical excavations can cause stress relief features and vertical ground settlement outside of the excavation. The grading contractor should be prepared to take necessary steps to provide lateral stability/temporary buttressing if slot cut sidewalls experience instability. The slot-cutting should be perform using the A-B-C Method (excavate the soil and place compacted fill in the A Areas, then the B areas, then the C areas). The slot cuts should not exceed 10 feet wide. Slot-Cutting Overexcavation Detail Alternatively, the lateral limits of grading for the building pad can be reduced from 10 feet to 2 feet, where necessary, to limit the potential for undermining of adjacent structure foundations. Comment 4:Please add temporary excavations and retaining wall subdrains to the list of geotechnical testing and observation services that should be performed during the construction of this project.(repeat comment – the requested tasks have been added to the “Construction Phase” column and not the “Observations” column of Table 7.15 of the submitted updated report; please add to the “observations” column.) Response: Table 7.15 of has been updated and is presented below. ~GEOCON PLAN VIEW CROSS-SECTION EXISTING GRADE A r B TEMPORARY 1:1 SLOPE The Roosevelt – Mixed Use Response to Review Comments Project No. G3112-52-01 - 4 - September 19, 2025 TABLE 7.15 EXPECTED GEOTECHNICAL TESTING AND OBSERVATION SERVICES Construction Phase Observations Expected Time Frame Grading Base of Removal and Temporary Excavations Part Time During Removals Fill Placement and Soil Compaction Full Time Foundations Foundation Excavation Observations Full Time Utility Backfill Fill Placement and Soil Compaction Part Time to Full Time Retaining Wall Backfill Fill Placement, Soil Compaction and Subdrains Part Time to Full Time Subgrade for Sidewalks, Curb/Gutter and Pavement Soil Compaction Part Time Pavement Construction Base Placement and Compaction Part Time Asphalt Concrete Placement and Compaction Full Time Should you have any questions regarding this correspondence, or if we may be of further service, please contact the undersigned at your convenience. Very truly yours, GEOCON INCORPORATED Nikolas Garcia, EIT Senior Staff Engineer Matt Love GE 3238 NG:ML:kv (e-mail) Addressee ~GEOCON - The Roosevelt – Mixed Use Response to Review Comments Project No. G3112-52-01 - 5 - September 19, 2025 LIST OF REFERENCES 1.Update Geotechnical Investigation, 2621 Roosevelt Street, Carlsbad California, Carlsbad, California, prepared by Geocon Incorporated, dated July 17, 2025 (Project No. G3112-52-01). 2.Grading Plans for: The Roosevelt Mixed Use, 2621 Roosevelt Street, Carlsbad, California, prepared by SWS Engineering, Inc., dated March 18, 2025. 3.Geotechnical Report Review (2nd), Land Development Engineering, 1635 Faraday Avenue, Carlsbad, CA (City of Carlsbad), dated August 19, 2025 (Project ID: SDP2024-0001). ~GEOCON