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Home My WebLink AboutCDP 2017-0064; SLOWIK ADU; UPDATED GEOTECHNICAL REPORT FOR NEW, ONE-STORY, SECOND DWELLING UNIT AND DETACH GARAGE; 2021-04-11EAST COUNTY SOIL CONSULTATION AND ENGINEERING, INC. Sharon Slowik 3960 Sunnyhill Drive Carlsbad, California 92008 10925 HARTLEY ROAD, SUITE "I" SANTEE, CALIFORNIA 92071 TEL. 619-258-7901 April 11, 2021 Project No. 03-l 106H6(A) Subject: Updated Geotechnical Report for New, One-Story, Second Dwelling Unit and Detached Garage 3960 Sunnyhill Drive Carlsbad, California 92008 Dear Ms. Slowik: In accordance with your request, we are pleased to submit this updated geotechnical report for the subject new, one-story, second dwelling unit and detached garage. We have reviewed the referenced Limited Site Investigation Report and Geotechnical Report Update, dated April 21 , 2004 and July 23, 2019, respectively (see attached Figure 1, References 2 and 3), and revisited the site. The recommendations presented in the referenced reports have been partially modified to reflect changes in the standard of practice in the industry and to conform to the current California Building Code. These recommendations should be incorporated into the project design and construction. SITE VISIT We revisited the site on April 6, 2021 . Conditions in the area of the proposed second dwelling unit and garage are similar to those described in the referenced geotechnical reports. Accordingly, we did not consider it necessary to perform additional subsurface exploration or soil testing. SEISMIC DESIGN VALUES Updated seismic design values are presented on the attached Figure 2. CONCLUSIONS The site is suitable for construction of the new, one-story, second dwelling unit and detached garage. The following updated footing and floor slab recommendations should be incorporated into the design and construction of the residence and garage, while the other recommendations presented in the referenced reports are still valid. Updated Geotechnical Report for New, One-Story, Second Dwelling Unit and Detached Garage 3960 Sunnyhill Drive Carlsbad, CA 92008 FOOTINGS Page2 April 11, 2021 Project No. 03-1106H6(A) Continuous and/or individual footings should be founded in dense terrace deposits at a minimum depth of 18 inches below building pad grade or lowest adjacent, finished grade, whichever is deeper. Continuous footings should be reinforced with a minimum of four #4 steel bars, with two bars placed near the top of the footings and the other two bars placed near the bottom of the footings. Individual footings should be at least 18 inches square and reinforced with a grid of #4 bars spaced 12 inches on centers ( each way) and placed on concrete blocks at the bottom of the footing. FLOOR SLABS Floor slabs including garage slabs should be at least 5 inches thick and reinforced with #4 bars placed at 18 inches on centers in two directions in the middle of the slab. The reinforcing steel should be supported on steel chairs or concrete blocks. Floor slabs should be underlain by 2 inches of clean sand over a 10-mil visqueen moisture barrier over 2 inches of clean sand. To minimize the potential for shrinkage cracks, floor slab concrete should have a rmmmum compressive strength of 3,000 psi and maximum water-cement ratio of 0. 5.. No special inspection of concrete is necessary. Some shrinkage cracks are still possible. ADDITIONAL SERVICES A review of plans and specifications, field observations and testing under our direction are integral parts of the recommendations made in this report. If East County Soil Consultation and Engineering, Inc. is not retained for these services, the client agrees to assume our responsibility for any potential claims that may arise during construction. Observation and testing are additional services, which are provided by our firm, and should be budgeted within the cost of development. This opportunity to be of service is appreciated. If you have any questions, or we can be of further service, please do not hesitate to call or contact us. Respectfully Submitted, Martin R. Owen, PE, GE Geotechnical Engineer Attachments: Figures 1 and 2 EAST COUNTY SOIL CONSULTATION AND ENGINEERING, INC. Updated Geotecbnical Report for New, One-Story, Second Dwelling Unit and Detached Garage 3960 Sunnybill Drive Carlsbad, CA 92008 FIGURE 1 REFERENCES Page3 April 11, 2021 Project No. 03-1106H6(A) 1. "Response to Third Party Review, Proposed Second Dwelling Unit, 3960 Sunnyhill Drive, City of Carlsbad, California", Project No. 03-1106H6(A), Prepared by East County Soil Consultation and Engineering, Inc., Dated July 23, 2019 . 2. "Geotechnical Report Update, Proposed New Primary Residence, 3960 Sunnyhill Drive, City of Carlsbad, California", Project No. 03-1106H6(A), Prepared by East County Soil Consultation and Engineering, Inc., Dated August 8, 2017. 3. "Limited Site Investigation, Proposed New Primary Residence, 3960 Sunnyhill Drive, City of Carlsbad, California", Project No. 03-1106H6(A), Prepared by East County Soil Consultation and Engineering, Inc., Dated April 21, 2004. 4. "Soil Bearing Value Recommendation, Proposed Second Story Addition, 3960 Sunnyhill Drive, City of Carlsbad, California", Project No. 03-1106H6(A), Prepared by East County Soil Consultation and Engineering, Inc., Dated July 16, 2003 . EAST COUNTY SOIL CONSULTATION AND ENGINEERING, INC. U1>dated Geotechnical Report for New, One-Story, Second Dwelling Unit and Detached Garage Page4 April 11, 2021 Project No. 03-1106H6(A) 3960 Sunnyhill Drive Carlsbad, CA 92008 FIGURE2 SEISMIC DESIGN VALUES 3960 Sunnyhill Dr, Carlsbad, CA 92008, USA ...... n-i ..1de. ' l Date Design Code Reference Document Risk Category Site Class Type Value Ss 1.02 S: 0.371 S,,,s 1.114 S.,.1 null -See Section 11.4.8 S::rs 0.742 SJ: null -See Section 11.4 .8 Type Value soc null -See Section 11.4.8 F. 1.092 F, null -See Section 11.4.8 PGA 0.447 Description Description 4/9/2021. 2:48:47 PM ASCE7-16 II D -Stiff Soil MCE._ ground motion. (for 0.2 second period) KER ground motion. (for 1.0s period) Site-modified spectral acceleration value Site-modified spectral acceleration value Numeric seismic design value at 0.2 second SA umeric seismic design value at 1.0 second SA Seismic design category Site amplification factor at 0.2 second Site amplification factor at 1.0 second ~KE:; pealc ground a::celeration EAST COUNTY SOIL CONSULTATION AND ENGINEERING, INC.