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Home My WebLink AboutCDP 07-12; SEARS RESIDENCE; FINAL SOILS REPORT; 2018-05-08FINAL GEOTECHNICAL REPORT Proposed Single-Family Residence 4015 Sunnyhill Drive Carlsbad, California HETHERINGTON ENGINEERING, INC. HETHERINGTON ENGINEERING , INC. SOIL & FOUNDATION ENGINEERING • ENGINEERING GEOLOGY • HYDROGEOLOGY Tom Sears May 8, 2018 Project No. 7842.1 Log No. 19823 1387 Cynthia Lane Carlsbad, California 92008 Subject: FINAL GEOTECHNICAL REPORT Proposed Single-Family Residence 4015 Sunnyhill Drive Carlsbad, California References: 1. "Geotechnical Investigation, Proposed Single-Family Residence, 4015 Sunnyhill Drive, Carlsbad, California," by Hetherington Engineering, Inc., dated September 18, 2007. 2. "Geotechnical Update, Proposed Single-Family Residence, 4015 Sunnyhill Drive, Carlsbad, California," by Hetherington Engineering, Inc., dated December 16, 2015. 3. "As-Graded Geotechnical Letter, Proposed Single-Family Residence, 4015 Sunnyhill Drive, Carlsbad, California," by Hetherington Engineering, Inc. dated February 24, 2017. 4. "Grading Plan For: Sear~ Residence, 4015 Sunnyhill Drive," by The Sea Bright Company, undated. Dear Mr. Sears: In accordance with your request, we have performed on call geotechnical services in conjunction with grading and construction at the subject site. Our services consisted generally of the following: • Observation and density testing during grading. • Observation and density testing during placement and compaction of retaining wall backfill. • Observation of footing excavations. • Laboratory testing. 5365 Avenida Encinas, Suite A • Carlsbad, CA 92008-4369 • (760) 931-1917 • Fax (760) 931-0545 333 Third Street, Suite 2 • Laguna Beach, CA 92651-2306 • (949) 715-5440 • Fax (760) 931 -0545 www. hetheringtonengi nee ring . com FINAL GEOTECHNICAL REPORT Project No. 7842.1 Log No. 19823 May 8, 2018 Page2 • Engineering and geologic analyses. • The preparation of this repo1i, which presents the results of our testing and observations, and our conclusions and recommendations. GRADING OPERATIONS Grading was performed in February 2017. Grading consisted generally of up to 4-feet of overexcavation to approved terrace deposits and placement of compacted fill to design site grades. The attached Plot Plan, Figure 1 indicates the approximate limits of grading addressed by this report. Grading for the driveway outside the limits of grading shown on the attached Plot Plan, Figure 1 was not observed or tested by this office. The earthwork was performed by Tom Sears utilizing grading plans prepared by The Sea Bright Company (Reference 4 ). Site Preparation Prior to grading, the site was cleared of existing surface obstructions, vegetation and debris. Within the grading area indicated on the attached Plot Plan, Figure 1, existing fill and loose tenace deposits were removed to depths of approximately 2.2 to 4-feet. Following removals, the exposed soils were scarified to a depth of 6 to 8-inches, brought to near optimum moisture conditions and compacted to at least 90-percent relative compaction as dete1mined by ASTM: D 1557. Soil Types The soils utilized as fill consisted of on-site and imp01i soils. The on-site soil consisted generally of silty sand and import soils consisted generally of silty sand and sand. Fill Placement Fill soils were placed in 6 to 8-inch thick, near horizontal lifts, moisture conditioned to near optimum moisture content, and compacted to at least 90-percent relative compaction as dete1mined by ASTM: D 1557. Compaction was achieved by mechanical means using a rubber tire loader and a bulldozer. A fire hose was used for moisture conditioning. Density tests were performed in accordance with ASTM: D 6938 (Nuclear Method). The results of the density tests are presented on the attached Summary of Field Density Tests, Table I. The approximate locations of the field density tests are indicated on the accompanying Plot Plan, Figure 1. Maximum dry density/optimum moisture content HETHERINGTON ENGINEERING, INC . FINAL GEOTECHNICAL REPORT Project No. 7842.1 Log No. 19823 May 8, 2018 Page 3 determinations are presented on the attached Summary of Maximum Dry Density/Optimum Moisture Content Determinations, Table II. RETAINING WALL BACKFILL Observation and testing of retaining wall backfill was performed in June 2017. The soils utilized as retaining wall backfill consisted of on-site and impo1ted soils. Retaining wall backfill soils were placed in approximately 6 to 8-inch thick, near horizontal lifts, moisture conditioned to near optimum moisture content and compacted by mechanical means to a minimum of 90-percent relative compaction as determined by ASTM: D 1557. Density tests were perfo1med in accordance with ASTM: D 6938 (Nuclear Method). The results of the density tests are presented on the attached Summary of Field Density Tests, Table I. The approximate locations of the field density tests are indicated on the accompanying Plot Plan, Figure 1. Maximum dry density/optimum moisture content determinations are presented on the attached Summary of Maximum Dry Density/Optimum Moisture Content Determinations, Table II. FOOTING EXCAVATIONS Footing excavations for the residential structure and retaining walls were observed to be embedded into competent te1rnce deposits or compacted fill as recommended (References 1 and 2). CONCLUSIONS It is our opinion that the geotechnical elements of grading and construction observed and tested by Hetherington Engineering, Inc. at the site have been performed in general confo1mance with our recommendations and the requirements of the city of Carlsbad. LIMITATIONS Our services were performed using the degree of care and skill ordinarily exercised, under similar circumstances, by reputable Geotechnical Consultants practicing in this or similar localities. No other warranty, express or implied, is made as to the conclusions and professional advice included in this report. HETHERINGTON ENGINEERING, INC. LEGENDAPPROXIMATE LOCATION OF DENSITY TESTOVEREXCAVATION DEPTHS RELATIVE TOEXISTING ADJACENT GRADES (FEET)24-4.0-4.0-2.2-3.0N PLOT PLANGEOTECHNICAL CONSULTANTSHETHERINGTON ENGINEERING,INC.PROJECT NO.FIGURE NO.01220 4001030SCALE: 1" = 20'7842.14015 Sunnyhill DriveCarlsbad, California986121124135119163142115102223201824177APPROXIMATE LIMITS OF GRADING APPROXIMATE LIMITS OF GRADING1ADDRESSED BY THIS REPORTADDRESSED BY THIS REPORTSINGLE F AMIL y OWELUNG --• • Project No. 7842.1 Log No. 19823 TABLE I SUMMARY OF FIELD DENSITY TESTS (ASTM: D 6938) Test No. Test Date Soil Type Elevation (feet) Dry Density (pcf) Moisture Content (%) Relative Compaction (%) 1 2/14/17 1 237.8 114.4 8.2 91 2 2/14/17 1 237.8 123.0 11.6 98 3 2/14/17 1 239.0 117.8 8.4 94 4 2/14/17 1 239.0 119.5 10.8 95 5 2/14/17 1 237.5 114.8 15.2 91 6 2/14/17 1 236.8 117.4 11.2 94 7 2/15/17 1 237.0 115.4 15.4 92 8 2/15/17 1 237.5 114.9 14.6 92 9 2/15/17 1 239.0 115.8 15.6 92 10 2/15/17 1 239.0 124.1 8.4 99 11 2/15/17 1 239.0 124.8 9.5 99 12 2/15/17 1 239.0 122.4 8.8 97 13 2/15/17 1 239.0 117.2 9.4 93 14 (R.W.) 6/1/17 1 239.3 117.1 9.1 93 15 (R.W.) 6/1/17 1 240.3 112.6 13.3 90 16 (R.W.) 6/1/17 1 240.8 111.4 12.3 90 17 (R.W.) 6/5/17 2 242.0 109.8 12.2 90 18 (R.W.) 6/5/17 2 242.0 110.4 10.0 91 19 (R.W.) 6/5/17 2 246.0 109.6 10.4 90 20 (R.W.) 6/5/17 2 243.0 111.1 13.4 91 21 (R.W.) 6/7/18 2 246.0 109.8 12.7 90 22 (R.W.) 6/7/18 2 245.8 110.0 10.4 90 23 (R.W.) 6/7/18 3 246.0 119.6 10.3 91 24 (R.W.) 6/7/18 3 246.0 122.1 9.4 92 R.W. – Retaining wall backfill TABLE II SUMMARY OF MAXIMUM DRY DENSITY/OPTIMUM MOISTURE CONTENT DETERMINATIONS (ASTM: D 1557A) Soil Type Description Maximum Dry Density (pcf) Optimum Moisture Content (%) 1 Brown silty sand 125.5 9.5 2 Yellow brown silty sand (import)121.5 10.5 3 Green brown sand (import)132.0 6.5