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Home My WebLink AboutCDP 2016-0004; 148 TAMARACK AVENUE; FINAL SOILS REPORT; 2020-03-16Final As-Graded Geotechnical Report for the Building Pads at 148 Tamarack Avenue Carlsbad CA, 92008 Prepared for the City of Carlsbad-Development Services February 16, 2022 148 Tamarack Ave -Final As Graded report JLVG/BJL 2/18/2022 Page I of 7 1.0 Introductory As-Graded Information 1.1 Report Outline The purpose of this report is to document our geotechnical observation and testing performed during grading for the proposed new two-story residence with new detached two-story structure consisting of a garage on the lower level and an apartment above at the subject property located at 148 Tamarack Avenue Carlsbad CA, 92008 from March 41\ 2020 to March 16th,2020. Geotechnical recommendations for this project was previously presented in the report entitled: Updated Geo technical Investigation for the Subject Property Located at 148 Tamarack Ave, Carlsbad, CA 92008 dated June 3,2019 by Applied Consultants. Our scope of work is limited to the observation and testing, and consulting services during grading at the subject property. The following services were performed by us during our grading inspections. • Compaction of the engineered fill was tested in accordance with the Sand Cone Method (ASTM D-1556). • Laboratory testing was performed to check soil conditions and strength parameters for design purposes. Tests included maximum dry density, in-place moisture and density. • As-Built Analyses -Geologic conditions observed during construction did not vary from those identified during our preliminary investigation. • As-Built Report -The following report has been prepared which outline the results of our observations, testing, and analyses. 1.2 Project Description and Identification The grading operations have been performed at 148 Tamarack A venue Carlsbad CA, 92008 The intended purpose of the grading was to prepare the lot of the subject property for the construction of the new two story residence with new detached two story structure. The submitted plans for this project are referenced by: Project#: GR2019-0015 Grading Plans by: BHAinc. 5115 A venida Encinas Suite "L" Carlsbad CA, 92008-4387 148 Tamarack Ave -Final As Graded report JL VG/BJ L 2/18/2022 Page 3 of 7 Grading contractor: Pacific Coast Grading 2726 Morning Glory Ln Carlsbad, CA 92008 Owner: Paisan Pinpokintr 148 Tamarack Ave, Carlsbad, CA 92008 1.3 Construction Summary The grading of the subject property lot was completed under the supervision of the general contractor. The grading operations were performed in two stages for the garage building pad and the main residence building pad respectively. • Stage I -Garage pad re-compaction The grading operations for the building pad were to: excavate from grade to a minimum of 36 inches below grade scarify the exposed surface and compact the local soils to the required grade. Prior to the backfill operations, a staff engineer from our firm inspected and approved the bottom key of excavation. Maximum depth of fill for the garage pad was 48 inches below finish grade towards the northwestern portion of the property. • Stage II -Main residence pad re-compaction The grading operations for the building pad were to: excavate from grade to a minimum of 36 inches below grade scarify the exposed surface and compact the local soils to the required grade. Prior to the backfill operations, a staff engineer from our firm inspected and approved the bottom key of excavation. Import soils were used as fill for the upper two feet of the main residence pad re-compaction feet. Maximum depth of fill for the main residence pad was 48 inches below finish grade towards the northeastern portion of the property. The grading of the building pads began on March 3rd, 2020 and was completed by March 16th, 2020. The local fill soils were mechanically excavated with a CAT938F Front loader and then compacted with the wheels of the CAT938F Front loader. The excavation and compaction of the local and import fill soils were extended generally to five feet outside of the proposed building footprints. 148 Tamarack Ave -Final As Graded report JL VG/BJL 2/18/2022 Page 4 of 7 • Stage III-Retaining walls The site retaining walls were constructed without our supervision, we did not observe the footing trenches and we did not monitor the backfill of the site retaining walls during construction. Compaction testing was performed for the retaining walls located at the south of the property with a maximum height of four feet. We were provided with testing windows, and we tested the fill soils at two feet below top of wall and at finish grade. Compaction results were greater than 90% of the maximum dry density in conformance with our recommendations. 1.4 Scope of Services We provided geotechnical engineering inspection services for the grading of the building pads. The geotechnical engineering characteristics of the local and import fill soils were determined according to: Optimum Moisture Content and Maximum Density-ASTM D1557 In-Place Density Test (Sand Cone Method) ASTM-1556 Geotechnical engineering inspections were conducted by a representative from our firm. 2.0 As-Graded Conditions 2.1 Geologic Conditions The geologic condition that was encountered at the site was as anticipated in our geotechnical inspection report for the subject property. We encountered a fine to coarse graded, orangish brown silty sand (SM) The import fill material used as fill for the upper two feet of the main residence pad was a fine to medium grained, yellowish dark brown well-graded sand with silt (SW-SM). No water was encountered at this site during grading operations. 2.2 Geotechnical Conditions The grading at the subject property did not require stabilization fill, buttress fill, or subsurface drainage. 3.0 Fill Placement and Compaction Testing During our observations we conducted in-place soil density tests and conducted geotechnical inspections throughout the duration of the project. 148 Tamarack Ave-Final As Graded report JL VG/BJL 2/I 8!2022 Page 5 of 7 The grading of the project began with excavation from grade to a minimum depth of 36 inches, the exposed surface was scarified and the local and import fill soils compacted to the required grade. Maximum depth of fill for the building pad was 48 inches below finish grade towards the northwestern portion and northeastern portion of the property. The local fill soils were mechanically excavated with a CAT938F Front loader and then compacted with the wheels of the CAT938F Front loader. The excavation and compaction of the local and import fill soils were extended generally to five feet outside of the proposed building footprints. Our tests for compaction of the fill materials were in accordance with ASTM guidelines. The compacted soils underwent the scrutiny of: -Optimum Moisture Content and Maximum Density -ASTM D1557 -In-Place Density Test (Sand Cone Method) ASTM-1556 The following is a summary of our density tests: Test# Elevation ( ft )/Location 4' below finish grade / Garage Pad T-1 2' below finish grade/ Garage pad T-2 1.5' below finish grade/ Garage pad 4' below finish grade / Garage Pad T-3 2' below FG / Main residence pad T-4 2' below FG / Main residence pad T-5 FGI Main residence pad T-6 FG I Main residence pad 148 Tamarack Ave -Final As Graded report JLVG/BJL 2/18/2022 Date March 3rd 2020 ' March 3rd 2020 ' March 3rd 2020 ' March 4th 2020 ' March 4th 2020 ' March 4th,2020 March 16th 2020 ' March 16th,2020 Page 6 of 7 Relative Compaction Approved key >90% >90% Approved key >90% >90% >90% >90% Notes Approved garage building pad excavation. Pass Pass Approved of main residence building pad excavation. Pass Pass Pass Pass T-7 FG I Garage pad March >90% Pass 16th 2020 ' 2' below finish T-8 grade / South February >90% Pass Retaining walls 14th 2022 , T-9 Finish grade / South February >90% Pass Retaining walls 14th 2022 ' 4.0 Conclusions It is our geotechnical engineering opinion that the soils for the building pads of the proposed new two-story residence with new detached two-story structure have been compacted in accordance with our recommendations and are suitable for its intended use. We certify that all remedial earthwork and grading to bring the site to grade for the proposed building pads were done in conformance with our recommendations. 148 Tamarack Ave -Final As Graded report JLVG/BJL 2/18/2022 Page 7 of 7 T-7 T-8 T-2 £XIST. 6' PUBUC URUTY fASfMENT P£R ---...i..-1!----l BOOK 961, PAGE J, R£C. 07-10-T92J PROPOSED 6' HIGH IIOOO FENC£ PORRON OF £X15T. WALL TO R£MA.IN 53.80 TG 52.20 I[ COR[ HO/.£ 1HROUGH [XIST. 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