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Home My WebLink AboutCDP 2017-0044; THOMPSON GEESBREGHT; FINAL SOILS REPORT; 2022-01-03@ COAST GEOTECHNICAL I CONSULTING ENGINEERING GEOLOGISTS January 3, 2022 John and Priscilla Geesbreght 4056 Skyline Road Carlsbad, California 92008 Subject: FINAL GEOTECHNICAL REPORT Proposed Guest House and Garage 4056 Skyline Road Carlsbad, California References: Please see Page 5 Dear Mr. and Mrs. Geesbreght: W.O. 674617 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 Civil Landworks. The project included the construction of a guest house and a garage. The structures are supported on continuous wall and column pad footings with slab-on-grade floors. Retaining walls ranging from 1.0 to 4.0 feet were constructed between the guest house and garage and along the southwest portion of the development. Grading on the site consisted of cuts up to 3.0 vertical feet and fills up to 2.0 feet. Coast Geotechnical GEOTECHNICAL CONDITIONS January 3, 2022 w.o. 674617 Page 2 of 6 The subject property is located in the Coastal Plains Physiographic Province of San Diego. The property is underlain at relatively shallow depths by Pleistocene Very Old Paralic Deposits. The Very Old Paralic Deposits are covered by relatively thin fill and/or top soil. Unweathered dense Very Old Paralic Deposits are considered dense and competent, which makes it suitable for the support of foundation and fill deposits. The Very Old Paralic Deposits are composed of reddish- brown fine to medium grained sand. CONSTRUCTION PHASE 1) Rough grading for the development was performed by John Smith Earthworks from May 9 through June 11, 2019. The remedial grading was observed and or tested by this firm on May 15, 2019, June 4 through 7, 2019 and June 10 through 11, 2019. 2) Caisson excavations for the garage were observed by this firm on December 9, 2019. The caisson excavations for the garage are founded into compacted fill deposits with an expansion potential in the very low range. 3) The continuous wall and column pad footing excavations for the guest house and site retaining wall for the support of the garage pad were observed by this firm on October 2, 2019. 4) 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 Geotechnical January 3, 2022 w.o. 674617 Page 3 of 6 5) 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. 6) The utility trench backfill consisted of on-site materials and was compacted with hand operated compaction equipment (whacker). The utility trench backfill within the building perimeter of the guest house was observed by this firm on October 2, 2019. CONCLUSIONS The geotechnical conditions encountered on the site were in substantial conformance with those conditions anticipated in the Preliminary Geotechnical Investigation Report. In general, the recommendations of the geotechnical reports were implemented during the grading and construction phases. 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 Geotechnical January 3, 2022 W.O. 674617 Page 4 of 6 Coast Geotechnical 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. 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 Geotechnical. If you have any questions regarding this report, please contact our office. Reference to our Job No. 674617 will help expedite a response to your inquiry. Respectfully submitted, COAST GEOTECHNICAL Mark Burwell, C.E.G. Engineering Geologist Enclosures: Compaction Test Results Grading Plan ✓~~~~ Vithaya Singhanet, P. Geotechnical Engineer Coast Geotechnical REFERENCES 1. PRELIMINARY GEOTECHNICAL INVESTIGATION Proposed Guest House and Garage 4056 Skyline Road Carlsbad, California Prepared by Coast Geotechnical Dated July 26, 2017 2. SUPPLEMENTAL REPORT FOR PROPOSED GRADING Proposed Guest House 4056 Skyline Road Carlsbad, California Prepared by Coast Geotechnical Dated January 8, 2018 3. FOUNDATION PLAN REVIEW Proposed Guest House 4056 Skyline Road Carlsbad, California Prepared by Coast Geotechnical Dated January 28, 2018 4. RESPONSE TO CITY OF CARLSBAD SDRSD C-01 Retaining Wall Proposed Guest House 4056 Skyline Road Carlsbad, California Prepared by Coast Geotechnical Dated July 2, 2018 5. GRADING PLAN REVIEW Proposed Guest House 4056 Skyline Road Carlsbad, California Prepared by Coast Geotechnical Dated December 12, 2108 January 3, 2022 w.o. 674617 Page 5 of 6 Coast Geotechnical 6. ROUGH GRADING REPORT Proposed Guest House 4056 Skyline Road Carlsbad, California Prepared by Coast Geotechnical Dated June 26, 2019 7. NOTICE OF FOOTING EXCAVATION OBSERVATION Proposed Residential Structure and Site Retaining Wall 4056 Skyline Road Carlsbad, California Prepared by Coast Geotechnical Dated October 3, 2019 8. NOTICE OF CAISSON EXCAVATION OBSERVATION Proposed Guesthouse and Garage 4056 Skyline Road Carlsbad, California Prepared by Coast Geotechnical Dated December 9, 2019 January 3, 2022 w.o. 674617 Page 6 of 6 ENCLOSURES COMPACTION TEST RESULTS PROJECT NO: 674617 PROJECT NAME: Greesbreght PROJECT LOCATION: 4056 Skyline Road, Carlsbad, CA FIELD COMPACTION TEST RESULTS (ASTM D1556): Approximate Field Max. Date Test Soil Approximate Test Field Moisture Dry Dry Relative Comments No. Type Test Elevation (MSL) (%) Density Density Compaction Location (ft) (pct) (pct) (%) 5/15/2019 I I Bldg Over-Ex 284 6.5 109.5 116.5 94 5/15/2019 2 I Bldg Over-Ex 289 9.3 107.7 116.5 92 6/4/2019 3 I Bldg Over-Ex 286 8 115.8 116.5 99 6/4/2019 4 I Bldg Over-Ex 289 8.2 109 116.5 94 6/4/2019 5 I Bldg Over-Ex 287.5 6.5 108.5 116.5 93 6/5/2019 6 I Bldg Over-Ex 288.5 6.7 115.2 116.5 99 6/5/2019 7 I Bldg Over-Ex 290 8.9 114.4 116.5 98 6/5/2019 8 I Bldg Over-Ex 290 9.1 114.8 116.5 99 6/6/20 I 9 9 I Bldg Over-Ex 290 8.6 113.7 116.5 98 6/6/2019 10 I Bldg Over-Ex 292 9.2 114 116.5 98 6/6/2019 II I Bldg Over-Ex 294 6.8 114.5 116.5 98 6/7/2019 12 I Bldg Over-Ex 296 7.9 113.7 116.5 98 6/7/2019 13 I Bldg Over-Ex 296 8.8 115.1 116.5 99 6/7/2019 14 I Bldg Over-Ex 297 6.2 113.2 116.5 97 6/10/2019 15 I Bldg Over-Ex 298 8.4 114.7 116.5 98 6/10/2019 16 I Bldg Over-Ex 296 6.9 115.8 I 16.5 99 6/10/2019 17 I Bldg Over-Ex FSG 7.3 114.3 I 16.5 98 6/11/2019 18 I Bldg Over-Ex FSG 6.6 113.9 I 16.5 97 6/11/20 I 9 19 I Bldg Over-Ex FSG 8.9 115 I 16.5 99 6/11/2019 20 I Bldg Over-Ex FSG 8.5 114.8 I 16.5 99 6/11/2019 21 I Bldg Over-Ex FSG 6.7 114.8 116.5 99 COAST GEOTECHNICAL