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HomeMy WebLinkAboutPD 2022-0001; ISBELL RESIDENCE; RESPONSE TO THIRD PARTY GEOTECHNICAL REVIEW (SECOND); 2022-05-09 7840 EL CAJON BLVD., SUITE 200 ♦ LA MESA, CALIFORNIA 91942 Phone: (619) 462-9861 ♦ Email: clamonte@flash.net ♦ Fax: (619) 462-9859 TO: SUBJECT: REFERENCES: This report has been prepared in response to the City of Carlsbad, Third-party Geotechnical Review, by Hetherington Engineering, Inc., dated February 22, 2022. In order to provide continuity of discussion, we are responding to the memorandum’s issues in the numerical order requested in the document. 1. The Consultant should provide the Seismic Design Category. No Seismic Design Category is provided on Page 6 of the report. . The Seismic Design Category is “D” as obtained from the ATC Hazards website. The data printout is attached. Job No. 21 7424 May 9, 2022 Response to Third-Party Geotechnical Review (Second) Isbell Residence Vacant Lot Adjacent to 2936 Cacatua St. Carlsbad, CA APN 215-390-35 Project No. 9621.1 Log No. 21852 City of Carlsbad Land Development Engineering 1635 Faraday Avenue Carlsbad, California 92008-7314 Report of Limited Geotechnical Investigation, Proposed Single-family Residence, Vacant Lot Adjacent to 2936 Cacatua St., Carlsbad, CA APN 215-390-35, by C. W. La Monte Company Inc., dated August 30, 2021 Grading Plan for: Isbell Residence, Cacatua Street, by dk Greene Consulting, Inc., dated December 17, 2021 Response to Third-Party Geotechnical Review, Isbell Residence, Vacant Lot Adjacent to 2936 Cacatua St., Carlsbad, CA, APN 215-390-35, Project No. 9621.1, Log No. 21852, by C. W. La Monte Company Inc., dated March 25, 2022 C. W. ta M~ CompsimJ B. 's'o'il a di °F'oY1 diati'oYl 1EYlt/iYl..,..,Ys Cacatua Street Carlsbad, CA March 25, 2022 Page 2 2. Foundation and slab Design criteria for expansive soils should be consistent with Section 1808.6 of the 2019 California Building Code. The Consultant should update foundation and slab recommendations as necessary. The expansion index was performed on a sample selected to represent the worst possible scenario and only represents a small area of the proposed building area. Further these soils are only marginally expansive. However, the majority of the lot consists of non-expansive, silty sand material. The foundation embedment depth and recommended reinforcement provided in the geotechnical report are appropriate for the prevailing subsurface conditions. In addition to the recommendations provided in the referenced report, we recommend any potentially expansive soils exposed in foundation and floor slab excavations be moisture conditioned if necessary. Any potentially expansive soils shall possess a moisture content of at least 2 percent above optimum moisture content. 3. The Consultant should specify the sulfate exposure category (ACI 318) based on soluble sulfate testing and provide recommendations for sulfate resistant concrete, if necessary, or default to a severe exposure category if testing is not available. A sulfate testing was performed on a representative sample by California Test 417. The test data is attached. Soluble sulfate content was determined to be negligible. No special recommendations are required. If you should have any questions after reviewing this document, please do not hesitate to contact our office. This opportunity to be of professional service is sincerely appreciated. Respectfully submitted, C.W. La Monte Company Inc. _____________________________ Clifford W. La Monte, R.C.E. 25241, G.E. 0495 12/31/2023 12/31/2023 L A B O R A T O R Y R E P O R T Telephone (619) 425-1993 Fax 425-7917 Established 1928 C L A R K S O N L A B O R A T O R Y A N D S U P P L Y I N C. 350 Trousdale Dr. Chula Vista, Ca. 91910 www.clarksonlab.com A N A L Y T I C A L A N D C O N S U L T I N G C H E M I S T S Date: April 21, 2022 Purchase Order Number: NONE Sales Order Number: 55323 Account Number: LAM To: *-------------------------------------------------* C W Lamonte Company 4400 Palm Avenue, Suite C, La mesa, Ca. 91941 Attention: Cliff Lamonte Laboratory Number: SO8755 Customers Phone: 619-462-9861 Fax: 619-462-9859 Sample Designation: *-------------------------------------------------* One soil sample received on 04/13/22 at 1:30pm, marked as follows: ANALYSIS: Water Soluble Sulfate (SO4) California Test 417 (Turbidity Method) Sample SO4% ----------------- #1 Cacatua St 0.004 __________________ Rosa Bernal RMB/arr Hazards by Location Search Information Address:3106 Unicornio St, Carlsbad, CA Coordinates:33.1130304, -117.2385608 Elevation:524 ft Timestamp:2022-04-24T23:41:34.269Z Hazard Type:Seismic Reference Document: ASCE7-16 Risk Category:II Site Class:C MCER Horizontal Response Spectrum Design Horizontal Response Spectrum Basic Parameters Name Value Description SS 0.933 MCER ground motion (period=0.2s) S1 0.342 MCER ground motion (period=1.0s) SMS 1.12 Site-modified spectral acceleration value SM1 0.513 Site-modified spectral acceleration value SDS 0.747 Numeric seismic design value at 0.2s SA SD1 0.342 Numeric seismic design value at 1.0s SA Additional Information Name Value Description SDC D Seismic design category Fa 1.2 Site amplification factor at 0.2s Fv 1.5 Site amplification factor at 1.0s 524 ft Report a map errorMap data ©2022 Google, INEGI 0 2 4 6 8 Period (s) 0.00 0.20 0.40 0.60 0.80 1.00 Sa(g) 0 2 4 6 8 Period (s) 0.00 0.20 0.40 0.60 Sa(g) CRS 0.905 Coefficient of risk (0.2s) CR1 0.915 Coefficient of risk (1.0s) PGA 0.406 MCEG peak ground acceleration FPGA 1.2 Site amplification factor at PGA PGAM 0.487 Site modified peak ground acceleration TL 8 Long-period transition period (s) SsRT 0.933 Probabilistic risk-targeted ground motion (0.2s) SsUH 1.031 Factored uniform-hazard spectral acceleration (2% probability of exceedance in 50 years) SsD 1.5 Factored deterministic acceleration value (0.2s) S1RT 0.342 Probabilistic risk-targeted ground motion (1.0s) S1UH 0.374 Factored uniform-hazard spectral acceleration (2% probability of exceedance in 50 years) S1D 0.6 Factored deterministic acceleration value (1.0s) PGAd 0.5 Factored deterministic acceleration value (PGA) The results indicated here DO NOT reflect any state or local amendments to the values or any delineation lines made during the building code adoption process. 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