The URL can be used to link to this page

Home My WebLink AboutCT 06-25; ROBERTSON RANCH PA 21; COMPACTION REPORT OF BUILDING PAD RE-CERTIFICATION; 2011-11-035741 Palmer Way Carlsbad, California 92010 (760) 438-3155 FAX (760) 931-0915 www.geosoilsinc.com November 3,.201 1 W.O. 6332-B-SC Brookfield Homes 12865 Pointe Del Mar, Suite 200 Del Mar, California 92014 Attention: Mr. Greg McDonnell Subject: Compaction Report of Building Pad Re-Certification, Model Lots 25, 26, and 27 of Planning Area 21, Robertson Ranch Development, Carlsbad, San Diego County, California References: 1. "Geotechnical Update for Planning Area 21, Robertson Ranch, East Village, City of Carlsbad, San Diego County, California," W.O. 5981-B-SC, dated May 25, 2011, by GeoSoils, Inc. "Discussion of Building Slab Subgrade Pre-Wetting, Planning Area 21 of Robertson Ranch, City of Carlsbad, California," W.O. 5949-C-SC, dated January 21, 2010, by GeoSoils, Inc. 'Report of Rough Grading, Planning Area 21 of Robertson Ranch, East Village Carlsbad, San Diego County, California," W.0. 5953-B1-SC, dated November 24, 2008, by GeoSoils, Inc. Dear Mr. McDonnell: GeoSoils, Inc. (GSI) is providing this summary of our observation and testing services during mitigative grading within Lots 25, 26, and 27 of Planning Area 21, at Robertson Ranch, East Village Subdivision in the City of Carlsbad, California. The purpose of remedial grading was to reprocess lots in accordance with recommendations presented in Reference No. 2, for the planned model lots. Earthwork consisted of re-processing surficial soils to a depth of approximately 8 to 12 inches, moisture conditioning, and compaction of soil to a minimum relative compaction of 90 percent per ASTM D 1557 (see Reference No. 2). Based on our observations and testing, the building pads appear to have been prepared in general accordance with the recommendations provided by this office (see Reference No.2 and No. 3), and are considered suitable for their intended use. Field Observation and Testing Field density tests were performed using nuclear (densometer) ASTM test methods D 2922 and D 3017. The test results taken during grading operations are presented in the attached copy of our "Field Testing Report." The laboratory maximum dry density and optimum moisture content for the major soil type within this construction phase were determined in general accordance with test method ASTM D 1557. The following table presents the results: SOIL TYPE . . :xIu DENSITY MOISTuaE CONTENT (PERCENT). Ix - Gray Brown, Clayey SAND 131.5 9.0 Field compaction testing indicates that the soils appear to meet the minimum compaction requirements previously established and adopted by the City of Carlsbad (i.e., at least 90 percent relative compaction per ASTM D 1557), and recent tests indicate over optimum soil moisture content, per GSI's reports (References 1 and 2). Should asignificant (i.e., 3 to 7 days) period of time pass prior to slab construction, additional moisture conditioning and/or re-establishing consistency, as well as pad subgrade proof testing may be necessary, prior to placement of the underslab vapor retarder (see Reference No. 1 and No. 2). Foundation Desicn/Construction Unless specifically superceded herein, the findings, conclusions, and recommendations presented in Reference No. 1, and Reference No. 3, are generally considered valid and applicable with respect to the construction and development of the subject building pads. Based on our review of Reference No. 3, the subject lots are low expansive, and categorized as foundation Category Ill, due to maximum fill depths beneath the lots. If building code updates are adopted prior to the development of these pads, an additional geotechnical update report may be necessary. CLOSURE The materials encountered on the project site and utilized for our analysis are believed representative of the area; however, soil and bedrock materials vary in character between excavations and natural outcrops or conditions exposed during mass grading. Site conditions may vary due to seasonal changes or other factors. Inasmuch as our study is based upon our review and engineering analyses and laboratory data, the conclusions and recommendations are professional opinions. These opinions have been derived in accordance with current standards of practice, and no warranty, either express or implied, is given. Standards of practice are subject to change with time. GSI assumes no responsibility or liability for work or testing performed by others, or their inaction; or work performed when GSI is not requested to be onsite, to evaluate if our recommendations have been properly implemented. Use of this report constitutes an agreement and consent by the user to all the limitations outlined above, notwithstanding any other Brookfield Homes Model Lots 25, 26, & 27, PA-21 Robertson Ranch File: e:\wpl2\6300\6332b.cro W.O. 6332-B-SC November 3, 2011 Page 2 Geotechnical Engineer, GE 2320 agreements that may be in place. In addition, this report may be subject to review by the controlling authorities. Thus, this report brings to completion our scope of services for this portion of the project. The opportunity to be of service is sincerely appreciated. If you should have any questions, please do not hesitate to contact our office. r Respectfully submitted-AA, RCG/ATG/J PF/jh Attachment: "Field Testing Report" GeoSolls, Inc Robert G. Crisma Engineering Geo Distribution: (1) Addressee (via email) (1) Brookfield Homes, Attention: Ms. Terri McHugh (via email) Brookfield Homes W.O. 6332-B-SC Model Lots 25, 26, & 27, PA-21 Robertson Ranch November 3, 2011 File:e:\wpl2\6300\6332b.cro Page 3 GeOSOUS, Eno. HELD TESTMNG REPORT W.O. 552-5-5i DATE NAME HOURS 2. CLIENT TRACT_PA21,2 -2 LOCATION8Z- /L 4&2 ________________________ CONTRACTOR SUPT. EQUIPMENT TEST NO. LOCATION ELEV. OR DEPTH MOISTURE CONTENT % DRY DENSITY P.C.F. % RELATIVE COMPACTION TEST TYPE SOIL TYPE / 25 /i. s ii , / AID < 2 3 4 27 727 7-7371--, i- COMMENTS: PAGE __________ 0/ E:/wp/for