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Home My WebLink AboutCT 2018-0006; LAGUNA DRIVE SUBDIVISION; FINAL SOILS REPORT; 2022-02-22@ COAST GEOTECH, INC. I CONSULTING ENGINEERS AND GEOLOGISTS February 22, 2022 (Revised from December 24, 2021) Brett Farrow Brett Farrow Architect 125 Mozart A venue Cardiff, CA 92007 Subject: FINAL GEOTECHNICAL REPORT Proposed 12 Residential Structures 570-580 Laguna Drive Carlsbad, California References: See Page 6 Dear Mr. Farrow: W.O. 686218 In response to your request, enclosed is our Final Geotechnical Report on the above referenced property. This report presents a summary of our geotechnical observations during the grading and construction phases. PROPOSED DEVELOPMENT Grading plans for site development were prepared by Pasco Laret Suiter and Associates. The project included the construction of twelve (12) residential condominium structures. The residences are supported on continuous wall footings with slab-on-grade floors. Grading on the site consisted of fills ranging from 3.0 to 8.5 feet. Coast Geotech, Inc. February 22, 2022 (Revised from December 24, 2021) w.o. 686218 Page 2 of 8 GEOTECHNICAL CONDITIONS The subject property is located in the Coastal Plains Physiographic Province of San Diego. The property is underlain at relatively shallow depths by Pleistocene Old Paralic Deposits. The Old Paralic Deposits are underlain at depth by Eocene-age sedimentary rocks commonly correlated with the Santiago Formation on published geological maps. The Old Paralic Deposits are covered by relatively thin soil deposits. Unweathered dense Old Paralic Deposits are considered dense and competent, which makes it suitable for the support of foundation and fill deposits. The Old Paralic Deposits are composed of tan reddish-brown fine to medium grained sand. CONSTRUCTION PHASE 1) Rough grading for the development was performed by Pacific Coast Grading from August 27 through September 23, 2020. The remedial grading was observed and or tested by this firm on August 28, 2020, August 31 through September 4, 2020, September 8 through 11, 2020, September 14, 2020, September 17 through 18, 2020 and September 21 through 23, 2020. 2) The continuous wall and column pad footing excavations for Units 1 through 6 of the development were observed by this firm on October 27, 2020. Units 7 through 9 were observed on November 25, 2020 and December 3, 2020. Units 10 through 11 were observed on January 4, 2021. Units 12 through 13 were observed on January 13, 2021. 3) The continuous wall and column pad footing excavations were founded into compacted fill deposits. The footing excavations were approved by this firm provided all loose deposits were removed from the base of the excavations prior to pouring concrete. The footing excavations were not reviewed for compliance with structural plans and location. Coast Geotech, Inc. February 22, 2022 (Revised from December 24, 2021) w.o. 686218 Page 3 of 8 4) Based on visual classification and previous laboratory testing, the mixture of soils utilized as compacted fill reflect an expansion potential in the very low range. 5) Utility line backfill for Units 1 through 6 were not observed/tested as the sand blanket and Visqueen were already in place at the time of footing excavation observation. The utility line backfill within the building perimeter for Units 7 through 13 were observed by this firm on December 3, 2020, January 4, 2021 and January 13, 2021. The utility trench backfill consisted of on-site materials and was compacted with hand operated compaction equipment (whacker). 6) The sewer main backfill on Laguna Drive was observed and tested by this firm on August 27, 2021, August 30, 2021 and September 1, 2021. 7) The water line backfill on Laguna Drive was observed and tested by this firm on November 17 through 18, 2021, November 23, 2021 and December 13, 2021 8) The storm drain backfill on Laguna Drive was observed and tested by this firm on December 10 through 11, 2021. 9) The subgrade and Class 2 base for the City of Carlsbad sidewalk, curb and gutter was observed and tested by this firm on December 16, 2021 and December 20 through 21, 2021. We did not observe or test portions of the sidewalk within the project property limits. 10) We did not observed the installation of cut off walls or driveway construction. It is our understanding that observation of these areas was under the supervision of the Civil Engineer. Coast Geotech, Inc. February 22, 2022 (Revised from December 24, 2021) w.o. 686218 Page 4 of 8 CONCLUSIONS The geotechnical conditions encountered on the site were in substantial conformance with those conditions anticipated in the Preliminary Geotechnical Investigation Report. The grading and construction phases were in substantial conformance with the recommendations of the geotechnical reports. Footings and slabs on grade should be protected from root and/or moisture migration. Undermining and pressure from roots and/or saturated soil conditions from infiltration can adversely affect foundations and slabs on grade. Irrigation should be limited to that amount necessary to sustain plant life. Over zealous irrigation can result in slope instability and settlement of foundations and concrete flatwork. LIMITATIONS This office assumes no responsibility for any alterations made without our knowledge and written approval, subsequent to the issuance of this report. All areas of disturbance which require the placement of compacted fill to restore them to the original condition will not be reviewed unless such backfilling operations are performed under our observation and tested for required compaction. It should be noted that density (compaction) testing is conducted on a very small volume of the fill. The intent is to provide an opinion, based on selective testing and observation during fill placement. Coast Geotech, Inc. cannot be responsible for areas not reviewed for soil compliance during construction. Such areas are the sole responsibility of the contractor. Geotechnical analysis of storm water infiltration was limited in scope. The long term effects of infiltration cannot be predicted with certainty and can only be evaluated through usage and time. However, in no respect do we guarantee or warrant the future performance of infiltration systems. Coast Geotech, Inc. February 22, 2022 (Revised from December 24, 2021) W.O. 686218 Page 5 of 8 This study has been provided solely for the benefit of the client and is in no way intended to benefit or extend any right or interest to any third party. This study is not to be used on other projects or extensions to this project except by agreement in writing with Coast Geotech, Inc. If you have any questions regarding this report, please contact our office. Reference to our Job No. 686218 will help expedite a response to your inquiry. Respectfully submitted, COAST GEOTECH, INC. Mark Burwell, C.E.G. Engineering Geologist Enclosures: Compaction Test Results Grading Plan J~~Av\11~ Vithaya mg Geotechnical Engin Coast Geotech, Inc. February 22, 2022 (Revised from December 24, 2021) w.o. 686218 Page 6 of 8 REFERENCES 1. NOTICE OF FOOTING EXCAVATION OBSERVATION, UNITS 12-13 Proposed 12 Residential Structures 570-580 Laguna Drive Carlsbad, California Prepared by Coast Geotech, Inc. Dated January 13, 2021 2. NOTICE OF FOOTING EXCAVATION OBSERVATION, UNITS 10-11 Proposed 12 Residential Structures 570-580 Laguna Drive Carlsbad, California Prepared by Coast Geotech, Inc. Dated December 24, 2020 3. NOTICE OF FOOTING EXCAVATION OBSERVATION, UNITS 7-9 Proposed 12 Residential Structures 570-580 Laguna Drive Carlsbad, California Prepared by Coast Geotech, Inc. Dated December 4, 2020 4. NOTICE OF FOOTING EXCAVATION OBSERVATION, UNITS 1-6 Proposed 12 Residential Structures 570-580 Laguna Drive Carlsbad, California Prepared by Coast Geotech, Inc. Dated October 27, 2020 5. ROUGH GRADING REPORT, UNITS 1-9 Proposed 12 Residential Structures 570-580 Laguna Drive Carlsbad, California Prepared by Coast Geotech, Inc. Dated September 23, 2020 Coast Geotech, Inc. February 22, 2022 (Revised from December 24, 2021) w.o. 686218 Page 7 of 8 6. ROUGH GRADING REPORT, UNITS 10-13 Proposed 12 Residential Structures 570-580 Laguna Drive Carlsbad, California Prepared by Coast Geotech, Inc. Dated September 21, 2020 7. DEEPENED GARAGE FOOTINGS AND CONSTRUCTION SEQUENCE RECOMMENDATIONS Laguna Drive Subdivision 570-580 Laguna Drive Carlsbad, California Prepared by Coast Geotech, Inc. Dated September 15, 2020 8. PERMEABLE PA VER DRIVEWAY Laguna Drive Subdivision 570-580 Laguna Drive Carlsbad, California Prepared by Coast Geotechnical Dated April 6, 2020 9. GEOTECHNICAL UPDATE REPORT 570-580 Laguna Drive Carlsbad, California Prepared by Coast Geotechnical Dated January 23, 2020 10. RESPONSE TO REVIEW COMMENTS OF GEOTECHNICAL REPORTS Laguna Drive Subdivision 570-580 Laguna Drive Carlsbad, California Prepared by Coast Geotechnical Dated January 14, 2020 11. THIRD GRADING PLAN REVIEW Proposed 13 Residential Structures 570-580 Laguna Drive Carlsbad, CA 92008 Prepared by Coast Geotechnical Dated December 19, 2019 Coast Geotech, Inc. 12. FOUNDATION PLAN REVIEW Proposed 13 Residential Structures 570-580 Laguna Drive Carlsbad, California Prepared by Coast Geotechnical Dated December 19, 2019 February 22, 2022 (Revised from December 24, 2021) w.o. 686218 Page 8 of 8 13. SUPPLEMENTAL RECOMMENDATIONS FOR A 3-STORY STRUCTURE Proposed 12 Residential Structures 570-580 Laguna Drive Carlsbad, California Prepared by Coast Geotechnical Dated November 21, 2019 14. SECOND GRADING PLAN REVIEW Proposed 12 Residential Structures 570-580 Laguna Drive Carlsbad, CA 92008 Prepared by Coast Geotechnical Dated January 14, 2019 15. GRADING PLAN REVIEW Proposed 12 Residential Structures 570-580 Laguna Drive Carlsbad, CA 92008 Prepared by Coast Geotechnical Dated August 6, 2018 16. PRELIMINARY GEOTECHNICAL INVESTIGATION Proposed 12 Residential Structures 570-580 Laguna Drive Carlsbad, CA 92008 Prepared by Coast Geotechnical Dated April 4, 2018 ENCLOSURES Test#/date Retest Max Dens rest Location/Sta# Elevation Wet Density Dry density % Moisture Requirment % Compaction Pass/Fail 19 130.0 Section G 35.5 131.0 121.3 8.0 90 93 Pass 20 130.0 Section E 39.0 132.9 122.4 8.6 90 94 Pass 21-9/4/20 130.0 Section G 36.5 126.7 117.2 8.1 90 90 Pass 22 130.0 Section G 38.0 123.7 115.3 7.3 90 89 Fail 23 130.0 Section G 38.0 125.5 116.2 8.0 90 89 Fail 24-9/8/20 22.0 130.0 Section G 38.0 130.1 119.1 9.2 90 92 Pass 25 23.0 130.0 Section G 38.0 127.9 117.0 9.3 90 90 Pass 26 130.0 Section G 39.0 130.6 118.0 10.7 90 91 Pass 27 130.0 Section E 40.0 125.3 117.1 7.0 90 90 Pass 28 -9/9/20 130.0 Section G 40.0 129.1 119.0 8.5 90 92 Pass 29 130.0 Section E 41.5 128.2 117.5 9.1 90 90 Pass 30 -9/10/20 130.0 Section G 41.0 125.6 116.1 8.2 90 89 Fail 31 30.0 130.0 Section G 41.0 131.0 120.1 9.1 90 92 Pass 32 -9/11/20 130.0 Section G 42.0 128.6 118.5 8.5 90 91 Pass 33 130.0 Section E 43.0 130.8 120.8 8.3 90 93 Pass 34 -9/14/20 130.0 Section I 41.0 129.8 117.8 10.2 90 91 Pass 35 130.0 Section H 41.0 129.9 118.4 9.7 90 91 Pass 36 130.0 Section H 42.0 128.7 118.6 8.5 90 91 Pass 37 -9/17/20 130.0 Section I 43.5 125.2 115.5 8.4 90 89 Fail 38 130.0 Section D 43.5 129.0 118.2 9.1 90 91 Pass 39 -9/18/20 124.0 Section D 43.5 119.1 110.6 7.7 90 89 Fail 40 124.0 Section G 44.0 122.1 112.5 8.5 90 91 Pass 41 -9/21/20 39.0 124.0 Section D 45.5 121.4 112.7 7.7 90 91 Pass 42 124.0 Section G 45.2 127.2 116.1 9.6 90 94 Pass 43 37.0 124.0 Section I 44.0 128.8 117.7 9.4 90 95 Pass 44 -9/22/20 124.0 Section H 44.2 118.3 110.8 6.8 90 89 Fail 45 44.0 124.0 Section H 44.2 120.3 112.2 7.2 90 90 Pass 46 -9/23/20 124.0 Section I 43.9 126.9 117.1 8.4 90 94 Pass 47 -8/27/21 130.0 Sewer Main 38.0 129.4 118.6 9.1 90 91 Pass 48 130.0 Sewer Main 38.0 129.3 118.0 9.6 90 91 Pass 49 130.0 Sewer Main 40.0 132.2 122.6 7.8 90 94 Pass 50-8/30/21 130.0 Sewer Main 42.0 134.0 123.6 8.4 95 95 Pass 51 130.0 Sewer Main SG 132.0 123.9 6.5 95 95 Pass Test#/date Retest Max Dens rest Location/Sta-Elevation Wet Density Dry density % Moisture Requirment % Compaction Pass/Fail 52 131.5 Sewer Main BG 130.0 125.6 3.5 95 96 Pass 53 131.5 Sewer Main BG 128.9 125.1 3.0 95 95 Pass 54 -9/1/21 146.0 Sewer Main AC 141.9 141.9 95 97 Pass 55 146.0 Sewer Main AC 143.5 143.5 95 98 Pass 56 -11/18/21 130.0 Water Line 42.0 136.6 124.1 10.1 95 95 Pass 57 130.0 Water Line 41.0 136.6 124.2 10.0 95 96 Pass 58 -11/23/21 131.5 Water Line BG 136.2 128.6 5.9 95 98 Pass 59 131.5 Water Line BG 134.6 126.7 6.2 95 96 Pass 60 146.0 Water Line AC 143.3 143.3 95 98 Pass 61 146.0 Water Line AC 139.2 139.2 95 95 Pass 62 146.0 Water Line AC 140.7 140.7 95 96 Pass 63 146.0 Water Line AC 138.6 138.6 95 95 Pass 64 146.0 Water Line AC 141.2 141.2 95 97 Pass 65 -12/10/21 130.0 Storm Drain 38.0 129.3 118 9.6 90 91 Pass 66 130.0 Storm Drain 40.0 131.3 120.2 9.2 90 92 Pass 67 -12/11/21 130.0 Storm Drain 42.0 133.5 123.8 7.8 95 95 Pass 68 130.0 Storm Drain 40.0 126.7 117.9 7.5 90 91 Pass 69 130.0 Storm Drain 42.5 134.4 123 9.3 95 95 Pass 70 130.0 Storm Drain SG 131.8 123.1 7.1 95 95 Pass 71 130.0 Storm Drain SG 134.1 124.5 7.7 95 96 Pass 72 131.5 Storm Drain BG 133.8 128 4.5 95 97 Pass 73 131.5 Storm Drain BG 133.3 128.5 3.7 95 98 Pass 74 -12/13/21 130.0 Water Line 41.0 126.6 118.1 7.2 90 91 Pass 75 130.0 Water Line SG 133.5 123.8 7.8 95 95 Pass 76 -12/16/21 130.0 Curb/Gutter SG 134.9 125.3 7.7 95 96 Pass 77 130.0 Curb/Gutter SG 134.9 125.7 7.3 95 97 Pass 78 130.0 Curb/Gutter SG 135.5 124.7 8.7 95 96 Pass 79 130.0 Curb/Gutter SG 131.5 123.5 6.5 95 95 Pass 80 145.3 Curb/Gutter BG 144.1 138.2 4.3 95 95 Pass 81 145.3 Curb/Gutter BG 143.7 138.6 3.7 95 95 Pass 82 145.3 Curb/Gutter BG 143.7 137.8 4.3 95 95 Pass 83 -12/20/21 130.0 Sidewalk SG 133.7 122.8 8.9 95 95 Pass 84 130.0 Sidewalk SG 131.1 122.4 7.1 95 95 Pass Test#/date Retest Max Dens rest Location/Sta# Elevation Wet Density Dry density % Moisture Requirment % Compaction Pass/Fail 85 145.3 Sidewalk BG 143.9 137.3 4.8 95 95 Pass 86 145.3 Sidewalk BG 144.4 137.5 5.0 95 95 Pass 87 146.0 Storm Drain (AC) AC 138.5 138.5 95 95 Pass 88 146.0 Storm Drain (AC) AC 143.2 143.2 95 98 Pass 89 146.0 Side of Street AC 138.9 138.9 95 95 Pass 90 -12/21/21 146.0 Water Line (AC) AC 139.9 139.9 95 96 Pass 91 146.0 Side of Street AC 141.1 141.1 95 97 Pass