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Home My WebLink AboutCDP 2019-0023; HERNANDEZ RESIDENCE; FINAL SOILS REPORT; 2021-10-20 GEOTECHNICAL | ENVIRONMENTAL | MATERIALS October 20, 2021 Project No. 3592.1-SD San Diego Building 38 Pine Avenue San Carlos, California 94070 Attention: Mr. Wyatt Van Driessche Subject: Final Report of Geotechnical Observation and Testing 3677 Garfield Street Carlsbad, California Dear Mr. Van Driessche: In accordance with your request, GeoTek, Inc. (GeoTek) has prepared this letter to summarize the completion of the earthwork construction associated with the subject property. The summary includes rough grading and post grading activities. Rough grading and earthwork construction were completed under the observation and selective testing by GeoTek between August 21st, 2020, and March 26th, 2020, as described in the previous Geotechnical Report dated August 31st, 2020 (GeoTek, 2020b). Post grading geotechnical observation and testing were performed on October 20th and 21st, 2020. SUMMARY OF GEOLOGIC AND SOILS CONDITIONS Based on our field observations and testing during remedial grading, we note the following:  Remedial grading consisted of removal of unsuitable surficial material to bedrock (Paralic deposits).  Overexcavated of the building pad was excavated to a depth of a least 12 inches below proposed foundations and brought to design pad grade elevations with engineered fill.  Engineered fill was placed and compacted to at least 90% and near optimum moisture content relative to ASTM D 1557 test procedures at the test locations.  A seepage pit system was encountered below the proposed building. The system was removed down to bedrock to an elevation of 49 feet above mean sea level. GeoTek, Inc. 1384 Poinsettia Avenue, Suite A Vista, CA 92081-8505 (760) 599-0509 Off, (760) 599-0593 Fa. www.geotekusa.com SAN DIEGO BUILDING, INC. October 20, 2021 Final Geotechnical As-Built Report Project No. 3592.1-SD 3677 Garfield Street, Carlsbad, California Page 2  The backfill for the utility tie-in connections from the curb to the utility’s point of connection with the main line was tested to be to be at least 95% relative compaction as determined by ASTM D1557 test procedures at the test locations.  Aggregate base (crushed miscellaneous base) placement was observed and tested to be to be at least 95% relative compaction as determined by plant provided information at the test locations.  Asphalt concrete placement was observed and tested to be to be at least 95% relative compaction as determined by plant provided information at the test locations.  Residential building foundation footings were observed and qualitatively evaluated with a soil probe to be firm and unyielding.  Visual classification of the soil in the field, compared to the soil description from laboratory testing, was the basis for determining the maximum dry density value and optimum moisture content applied to each soil density test. Manufactured materials, such as aggregate base and hot mixed asphalt, the supplier was contacted for maximum density values. Field and Laboratory Testing FIELD TESTING Field density tests were taken at periodic intervals and random locations to check the compaction efforts by the grading contractors. The field density testing for the subject site was performed using a nuclear gauge, in general accordance with testing procedure ASTM D 6938 for soils. The results of the field density testing conducted for the herein reported site area are included in the attached Tables 1 and presented on Figure 1. LABORATORY TESTING The laboratory maximum dry density and optimum moisture content for the soils were determined in general accordance with test method ASTM D 1557. The table below presents the soil type used for this project. SUMMARY OF LABORATORY MAXIMUM DRY DENSITY AND OPTIMUM MOISTURE CONTENT TEST RESULTS (ASTM D 1557) Soil Type Description Maximum Dry Density (pcf) Optimum Moisture Content (%) A Reddish Brown Sand with Silt 123.9 9.5 GEOTEK SAN DIEGO BUILDING, INC. October 20, 2021 Final Geotechnical As-Built Report Project No. 3592.1-SD 3677 Garfield Street, Carlsbad, California Page 3 CONCLUSIONS Site grading has been completed in general accordance with the approved geotechnical reports (GeoTek, 2019a and 2020a), applicable provisions of the 2019 California Building Code (CBC) and city of Carlsbad guidelines. Preliminary foundation recommendations were presented in our 2019 report and were considered to be final. If a significant amount of time elapses between the grading and reprocessing reported as part of this report and start of home construction, building pads may require additional reprocessing. The reprocessing should include moisture conditioning to a minimum content of optimum moisture based on ASTM D1557 and to a depth of at least a 12-inches prior to excavation of foundation footings. The opportunity to be of service is sincerely appreciated. If you should have any questions, please do not hesitate to call our office. Respectfully submitted, GeoTek, Inc. Christopher D. Livesey Gaby M. Bogdanoff CEG 2733, Exp. 05/31/23 GE 3133, Exp. 06/30/22 Associate Vice President Project Engineer Distribution: (1) Addressee via email Enclosures: Figure 1 – Field Density Test Location Map Table 1 – Field Density Tests GEOTEK SAN DIEGO BUILDING, INC. October 20, 2021 Final Geotechnical As-Built Report Project No. 3592.1-SD 3677 Garfield Street, Carlsbad, California Page 4 REFERENCES GeoTek, Inc, 2019, Preliminary Geotechnical Evaluation, 3677 Garfield Street Carlsbad, California, Project No. 3592-SD, dated October 18, 2019. _____, 2020a, Plan Review and Response to Review Comments, 3677 Garfield Street, Carlsbad, California, Project No. 3592-SD, dated February 16, 2020. _____, 2020b, Letter of Completion of Rough Grading, 3677 Garfield Street, Carlsbad, California, Project No. 3592.1-SD, dated August 31, 2020. GEOTEK Hernandez Residence 3677 Garfield Street Carlsbad, CA 92008 GeoTek, Inc. Grading 8/28/2020 Project No.: 3592.1-SD Page 1 of 1 DATE Test No.Location Lot No. Sta No. Elev/ Depth Moisture Content (%) Dry Density (pcf) Soil Type Maximum Density (pcf) Test Type Relative Compaction (%) 08/21/20 1 House Pad - Seepage Pit 1 N/A 51.0 10.5 115.3 A 123.9 N 93 08/21/20 2 House Pad - Seepage PIt 1 N/A 53.0 11.0 114.2 A 123.9 N 92 08/21/20 3 House Pad - Seepage Pit 1 N/A 54.0 10.2 116.7 A 123.9 N 94 08/21/20 4 House Pad - West 1 N/A 56.0 10.8 115.8 A 123.9 N 93 08/21/20 5 House Pad - South 1 N/A 57.0 9.9 115.6 A 123.9 N 93 08/21/20 6 House Pad - Northeast 1 N/A 56.0 10.0 118.2 A 123.9 N 95 08/21/20 7 House Pad - North 1 N/A 56.0 10.7 119.1 A 123.9 N 96 08/24/20 8 House Pad - West 1 N/A 59.0 10.2 116.2 A 123.9 N 94 08/25/20 9 House Pad Southeast 1 N/A FG 10.9 120.1 A 123.9 N 97 TABLE 1 SUMMARY OF FIELD DENSITY TESTS Grading Note: N = Nuclear Guage Test FG = Finished Grade Test All elevations are approximate 3677 Garfield Carlsbad, CA GeoTek, Inc. Utility Tie-In Backfill 10/8/2021 Project No.: 3592.1-SD DATE Test No.Location Lot No. Sta No. Elev/ Depth Moisture Content (%) Dry Density (pcf) Soil Type Maximum Density (pcf) Test Type Relative Compaction (%) 10/21/20 1 Garfield Street SG 10.3 121.1 A 123.9 N 98 2 Garfield Street AB 9.6 119.9 AB* 122.0 N 98 3 Garfield Street AC 143.5 AC* 148.0 N 97 TABLE 1 SUMMARY OF FIELD DENSITY TESTS Utility Tie-In Backfill Note: N = Nuclear Guage Test FG = Finished Grade Test All elevations are approximate *Plant Provided Value 213456789AfAfQopQop<Outside of Project Area><Outside of Project Area>545549551384 Poinsettia Avenue, Suite AVista, California 92081PN: 3592.1-SDDATE: October 2019Figure 1Field Density Test Location MapHernadez Residence3677 Garfield StreetCarlsbad, CA0 5 1020Scale: 1" = 10'NPlan adapted from "Precise Grading Plan" by Chereskin ArchitectureLegend Approximate Location of Field Density Test Approximate Limits of Site Approximate Limits of Remedial Grading Seepage Pit Approximate Location of Removal Bottom (Elevation) Artificial Fill Paralic Deposits (Circled)954AfQop59.20 "G .. ... .. ..... . r-·' 0 . 59~50 ~·=..:,J;,, j, ES--.w&_ -APN: 204-232-05 APN: 204-232-0J PROP. ·G1S' ME1ER PROP; El.E.CTRIC METER 62.50 ffi 62. 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