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Home My WebLink AboutCDP 2019-0009; AKIN RESIDENCE; FINAL SOILS REPORT; 2024-06-21 21 June 2024 Sadri and Rose Akin Job No. 19-12322 8839 San Badger Way Elk Grove, CA 95624 Subject: Final As-Graded Report Akin Residence 5290 Carlsbad Boulevard Carlsbad, California Dear Mr. and Mrs. Akin: Per the request of Mr. Joseph Bayani and as required by the City of Carlsbad Public Works Inspector, Geotechnical Exploration, Inc. hereby presents this final as- graded report of earthwork observations and soil testing for the work performed at the site between November 11, 2021, and April 12, 2024. Refer to Vicinity Map, Figure No. I, for project location. The observed earthwork was performed in accordance to the recommendations presented in our Report of Preliminary Geotechnical Investigation dated July 03, 2019. FIELD OBSERVATIONS 1. Our representative observed the overexcavation for the building pad, which consisted of removing between 3 and 4 feet of the existing upper fill soils, down to a suitable formational bottom. Our representative probed the bottom of the overexcavation, which was observed to be founded in dense suitable Old Paralic Deposits, Unit 6-7 (Qop6-7). The overexcavation of the building pad extended at least 5 feet beyond the building footprint where feasible. Akin Residence Job No. 19-12322 Carlsbad, California Page 2 Backfilling of the residential building pad overexcavation (including the driveway, porch, and rear patio) was observed and tested. The backfill material consisted primarily of soils with very low to low expansion potential. The grading contractor placed soil lifts not exceeding 8 inches in thickness. Density and moisture tests were taken once the soil lifts reached approximately 2 feet in height. Compaction tests yielded the recommend degree of compaction and moisture up to the finished pad grade. 2. The final footing excavation bearing soils for exterior and interior continuous and column footings were observed and probed. See Figure No. II, Plot Plan and Site-Specific Geologic Map, for test locations and other information. The footing excavation soils probed suitable and unyielding and a memo was given to the contractor/contractor’s representative on April 6, 2022. The observed footing excavations were in accordance to the approved structural plans by Patterson Engineering dated August 3, 2022. SOIL TESTING Representative soil samples were collected during the earthwork to determine laboratory maximum dry density of the soils per ASTM D1557. Field density tests were performed at approximate locations shown on Figure No. II, Plot Plan in accordance with ASTM D6938. The complete list of field density tests results is shown as Table A, Figure No. IIIa, and laboratory soil compaction test results are shown as Table B, Figure No. IIIb. Equipment used during earthwork compaction consisted of a backhoe with wheel tire pressure and a pneumatic hand tamper. A water truck was used when needed to increase the soil moisture. Field density tests yielded a relative compaction of at least 90 percent of maximum dry density at the tested locations. On-site and Akin Residence Job No. 19-12322 Carlsbad, California Page 3 imported soil materials were used at the project site. The on-site material consisted of dark and light reddish-brown silty sand and the imported soil material consisted of dark brown decomposed granite (D.G.). The on-site soils were determined to have low expansion with an expansion index of 1, per ASTM D4829. Proper finished drainage for the site was to be implemented by the general contractor prior to completing construction. SITE SUITABILITY AND COMPLIANCE In our professional opinion the dense formational soils are suitable to support the observed and tested recompacted fill areas, structural building foundations, and prepared areas for new exterior improvements. We certify that the soil engineering and engineering geologic aspects of the observed grading are in compliance with the approved geotechnical report and city approved plans, and the City of Carlsbad grading ordinance. LIMITATIONS The findings and opinions presented herein have been made in accordance with currently accepted principles and practice in the field of geotechnical engineering in in the City of Carlsbad. No warranty, either expressed or implied, is made. All statements in this report are applicable only for the grading and backfill operation observed and tested by our firm. The firm Geotechnical Exploration, Inc. shall not be held responsible for fill soils placed without our observations and testing at any other time, or subsequent changes to the site by others, which directly or Akin Residence Job No. 19-12322 Carlsbad, California Page 4 indirectly cause poor surface or subsurface drainage, water erosion, and/or alteration of the strength of the compacted fill soils. It is not within the scope of our services to provide quality control oversight for surface or subsurface drainage construction or retaining wall sealing and base of wall drain construction. It is the responsibility of the contractor to verify proper wall sealing, geofabric installation, protection board installation (if needed), drain depth below interior floor or yard surfaces, pipe percent slope to the outlet, etc. In the event that any changes in the nature, design, or location of the building or improvements are planned, the conclusions and recommendations contained in this report should not be considered valid unless the changes are reviewed and the conclusions of this report modified or verified in writing. This opportunity to be of service is sincerely appreciated. If you have any questions regarding this letter, please contact our office. Reference to our Job No. 19-12322 will help expedite a response to your inquiry. Respectfully submitted, GEOTECHNICAL EXPLORATION, INC. _______________________________ ______________________________ Jaime A. Cerros, P.E. Richard A. Cerros, P.E. R.C.E. 34422/G.E. 2007 R.C.E. 94223 Senior Geotechnical Engineer VICINITY MAP Proposed Akin Residence 5290 Carlsbad Boulevard Carlsbad, CA. Figure No. I Job No. 19-12322 SITE Thomas Bros. Guide San Diego County, pg 1126-G2 Approximate Location of Proposed Structure Approximate Location of Existing Structure Approximate Limits of Grading Proposed Akin Residence 5290 Carlsbad Boulevard Carlsbad, CA. Figure No. IIa Job No. 19-12322 19-12322-p2.ai LEGEND PLOT PLAN AND SITE SPECIFIC GEOLOGIC MAPREFERENCE: This Plot Plan is not to be used for legal purposes. Locations and dimensions are approximate. Actual property dimensions and locations of utilities may be obtained from the Approved Building Plans or the “As-Built” Grading Plans. REFERENCE: This Plot Plan was prepared from an existingSITE PLAN by CHRISTENSEN ENGINEERING & SURVEYINGdated 09-16-20 and from on-site field reconnaissanceperformed by GEI. CA R L S B A D B O U L E V A R D Updated June 2024 GRAPHIC SCALE ( 1” = 15’ ) 0 1515 N GEOLOGIC LEGEND Approximate Bottom of Excavtion (feet) 53’ 53’ 55’ 53’ 52’ 13 Approximate Location of Field Density Test 7 6 5 2 4 1 3 13 12 8 9 10 11 Quaternary Old Paralic Deposits (units 6-7) Artificial Fill Qaf Qop 6-7 Qaf Qop6-7 Qaf Qop6-7 Qaf Qop 6-7 Footings Observed 4-6-22 Interior Sewer Lines REFERENCE: This Plot Plan was prepared from an existing FOUNDATION PLAN by MARTIN ARCHITECTURE dated AUGUST 03, 2020 and from on-site field reconnaissance performed by GEI. LEGEND NOTE: This Plot Plan is not to be used for legal purposes. Locations and dimensions are approximate. Actual property dimensions and locations of utilities may be obtained from the Approved Building Plansor the “As-Built” Grading Plans. 18-12049-FTGS-8-2023.ai Proposed Akin Residence 5290 Carlsbad Boulevard Carlsbad, CA. Figure No. IIb Job No. 19-12322 PLOT PLAN June 2024 N Scale: 1” =20’ (approximate) 0 10 20 3020 TABLE A Approximate Water Dry Degree of Test Elevation Content Density Compaction Compaction No. Date of Test Test Location (Feet) (%) (pcf) (%) Curve No. Remarks 1 11/18/21 House Building Pad (Northeast Area) FSG-2' 5.2 122.5 97 2 2 11/18/21 House Building Pad (Northeast Area) FSG-2' 5.2 117.3 93 2 3 11/19/21 House Building Pad (Southeast Corner Area) FSG-2' 5.4 116.2 92 2 4 11/19/21 House Building Pad (Northwest/ Garage Area) FSG-2' 6.1 122.5 94 1 5 11/19/21 House Building Pad (North Side) FSG-1' 9.2 124.0 95 1 6 11/19/21 House Building Pad (Center Area) FSG-1' 6.5 124.2 96 1 7 11/19/21 House Building Pad (Southwest Corner Area) FSG-1'6.0 121.6 97 2 8 11/19/21 House Building Pad (East Area/ Porch Area) FSG-1'10.6 123.3 98 2 9 11/30/21 Landscaped Area/ Driveway FSG-1'7.2 126.4 97 1 10 11/30/21 West Area/ Back Patio FSG-1'6.7 126.0 97 1 11 1/24/22 West Area/ Back Patio FSG 7.4 123.1 93 3 12 1/24/22 House Building Pad (South Area) FSG 8.2 124.5 94 3 13 1/24/22 House Building Pad (Northwest Area)FSG 8.8 122.0 92 3 Job No. 19-12322 Figure No. IIIa SUMMARY OF FIELD DENSITY TEST RESULTS (ASTM D1556 and/or ASTM D6938) Notes: 1) Curve number refers to Table B 2) FSG denotes finish subgrade elevation 3) FBG denotes finish base grade elevation 4) FPG denotes finish pavement grade Job No. 19-12322 Figure No. IIIb TABLE B LABORATORY COMPACTION TEST RESULTS (ASTM D1557) Compaction Maximum Optimum Test Source of Dry Density Water Content Curve No. Description of Material Material (pcf) % 1 (SM) Silty Sand, Dark Reddish Brown On-site 130.0 8.1 2 (SM) Silty Sand, Light Red Brown On-site 126.0 7.2 3 (SM) Silty Sand-D.G, Dark Brown Import 132.5 8.0