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Home My WebLink AboutCT 04-26; ROBERTSON RANCH PA 16, 17 & 18; COMPACTION REPORT OF BUILDING PAD RE-CERTIFICATION; 2010-04-07tu!. - -Geotechnical . Geologic . Coastal • Environmental 5741 Palmer Way • Carlsbad, California 92010 • (760) 438-3155 • FAX (760) 931-0915 www.geosoilsinc.com April 7, 2010 W.O. 5949-13-SC Brookfield Homes 12865 Pointe Del Mar, Suite 200 Del Mar, California 92014 Attention: Ms. Teri McHugh Subject: Compaction Report of Building Pad Re Certification, Lots 128, 129, and 130, Planning Area 16, Robertson Ranch Development, City of Carlsbad, San Diego County, California References: 1. "Report of Rough Grading, Planning Area 16 of Robertson Ranch, East Village (Lots 44 through 63,89 through 99, 117 through 140, and 160 through 189), Carlsbad Tract 04-26, Drawing 453-8A, Carlsbad, San Diego County, California," W.O. 5353-131-SC, dated February 16, 2009, by GeoSoils, Inc. "Grading plans for Robertson Ranch PA 16, 17, 18, Sheets 10 and 13, Job no. 01-1014, Carlsbad Tract C.T. 004-26, Drawing no.453-8A, dated August, 2008, by O'Day Consultants, Inc. "California Building Code," dated 2007, by California Building Standards Commission. "California Building COde," dated 2001, by International Conference of Building Officials. Dear Ms. McHugh: GeoSoils, Inc. (GSl) is providing this summary of our observation and testing services of grading within Lots 128, 129, 130 within Planning Area 16, at the Robertson Ranch Subdivision in the City of Carlsbad, California. Planning area 16 was initially graded with observation and testing services provided by GSI (see Reference No. 1). The purpose of remedial grading was to re-condition the building pads and/or fill in a pre-existing desilting basin located within a portion of the subject lots. Remedial grading consisted re-processing surficial soils, moisture conditioning, and compacting the soil to a minimum relative compaction of 90 percent per ASTM D 1557. Based on our observations and testing, the building pads appears to have been prepared in general accordance with the recommendations provided by this office (see Reference No. 1), and are considered suitable for their intended use. Field Observation and Testing As previously indicated, the purpose of grading was to re-condition the building pads and/or fill in a pre-existing desilting basin located within a portion of the subject lots. Fills placed during this phase of site work varied up to approximately 3 feet in thickness. Fill soils placed within the subject lots were derived from soil stockpiles within the adjacent Planning Area 14. 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 copies of our "Field Testing Report(s)." The laboratory maximum dry density and optimum moisture content for the major soil type within this construction phase were determined according to test method ASTM D 1557. The following table presents the results: F_ SOIL TYPE MAXIMUM DENSITY (PCF) MOISTURE CONTENT (PERCENT) A - Brown, Silty SAND 127.0 10.0 E - Dark Brown, Silty SAND 126.0 11.0 0- Brown Gray, Gravelly SAND 131.0 9.0 S - Yellowish Gray, SAND w/CLAY 124.0 11.0 Field compaction testing indicates that the soils appear to meet the minimum compaction requirements previously established and adopted by the City of Carlsbad ([2007 California Building Codel i.e., at least 90 percent relative compaction per ASTM D 1557), and testing also indicates adequate soil moisture. However, based on the highly expansive character of site soils (see Reference No. 1), and the anticipated additional time that will pass prior to slab construction, additional moisture conditioning and verification will likely be necessary prior to placement of the underslab vapor retarder (see Table A, Note 11, and Pacie 12 of the referenced report). Soil Expansion, and Corrosion Potential A review of Reference No. 1 indicates that very highly expansive soils underlie these lots (expansion index > 130), as classified by 2001 California Building Code ([CBC], International Conference of Building Officials [lCBO], 2001), Table 18A-1-B. Please note that GSI utilizing this previous CBC code only to classify the soils, as the 2007 CBC (California Building Standards Commission [CBSC], 2007) does not provide this index. Subsequent corrosion testing of soils within 3 feet of finish grade indicate that these soils present a negligible (sulfate class SO) sulfate exposure to concrete, per Table 4.2.1 and Brookfield Homes W.O. 5949-B-SC Lots 128 130 PA 16 Robertson Ranch April 7 2010 File e \wpl2\5900\5949b cr016 Page 2 GeoSoils, Inc. 4.3.1 of the American Concrete Institute (ACI) document 318-08(2007 CBC [CBSC, 2007]). Soils are relatively neutral with respect to soil acidity/alkalinity (pH of 7.9), and are considered corrosive to exposed ferrous metals in a saturated state. The chloride ion content in soil was also noted to generally be below action levels (300 ppm [see Reference No. 1]). It is our understanding that standard concrete cover over reinforcing steel is usually appropriate for these conditions; however, a corrosion engineer should be consulted to provide specific recommendations regarding foundations and piping, etc. Foundation Design/Construction Based on a review of Reference No. 1 and observations/testing performed during this phase of site grading, foundations should be designed and constructed in accordance with recommendations presented in Reference No. 1 for Category IV post-tension foundations. As of this date, the site has not changed significantly since the completion of grading. Unless specifically superceded herein, the findings, conclusions, and recommendations presented in Reference No. 1 are generally considered valid and applicable with respect to the construction and development of the subject building pads. Based on the duration of time following pad completion, pre-wetting/saturation is recommended, as indicated in the referenced GSI report. 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 perlormed 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 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. Brookfield Homes W.O. 5949-B-SC Lots 128-130, PA 16, Robertson Ranch April 7, 2010 FiIe:e:\wpl2\5900\5949b.crol6 Page GeoSoils, Inc. The opportunity to be of service is sincerely appreciated. If you should have any questions, please do not hesitate to contact our office. Respectfully submitted lea. C GeoSoils Inc. /tAAL Q Certified or IC, N Engineering EC. N, Robe G. Crisman Andrew T. G atelli Engineering Geologist, q Geotechnical Engineer, GE 2320 RCG/ATG/JPF/jh Attachment: "Field Testing Reports" Distribution: (4) Addressee ..______________ DATE NAME ENTERED NOV 16 2Ot ' HOURS_____________ CLIENT ____________________TRACT _ # LOCATION___________________ SUPT._____________________ CONTRACTOR EQUIPMENT TEST NO. LOCATION ELEV. OR DEPTH MOISTURE CONTENT % DRY DENSITY P.C.F. % RELATIVE COMPACTION TEST TYPE SOIL TYPE A00 4 Al's IIZ1 /Jo A AN 1/l9 mb 5 99 u&' I t- 3 /' Ø /-4 /j,d'LFg0 ZAi L w 1_11141a4i- 1Jm , /) 'fJ5)Q3/ ',J 77 ViCe lilf F ears /f#'4u 4T gA , 7AWr COMMENTS: GeoSoils, Inc. BY: PAGE 1 OF I This field report presents a summary of observations and testing by Geosoils, Inc. personnel only where the tests were performed. Our work does not include supervision or direction of the actual work of the contractor, his employees, or agents. The Contractor should be informed that neither the presence of our field representative, nor the observation and testing by our firm, shall excuse him in any way for defects discovered in his work. It is understood that our firm will not be responsible for job or site safety on this project. I IF fr ENTERED NOV 2 't 2009 w.o.___________ DATE NAME_____________ HOURS CLIENT t'CtYf/&1J TRACT /31/6 LOCATION____________________ SUPT. _-_4 CONTRACTOR EQUIPMENT _/i?4-?7),.. A46A /i TEST NO. LOCATION ELEV. OR DEPTH MOISTURE CONTENT % DRY DENSITY P.C.F. % RELATIVE COMPACTION TEST TYPE SOIL TYPE &r lzg 140 I A bK -15 /3 /.3j / Ei q3/ " ft V p i/ui 6 47A446- ,W? #b 4 i' /r dA'770AA64 ii c /• £ L VnJC 7 Ifl,L7'- /5, V/rV/7v / COMMENTS: GeoSoils, Inc. BY: PAGE This field report presents a summary of observations and testing by Geosoils, Inc. personnel only where the tests were performed. Our work does not include supervision or direction of the actual work of the contractor, his employees, or agents. The Contractor should be informed that neither the presence of our field representative, nor the observation and testing by our firm, shall excuse him in any way for defects discovered in his work. It is understood that our firm will not be responsible for job or site safety on this project. IT; W.O. -8'E DATE __________ NAME_____________ HOURS ENTERED DEC 1312009 CLIENT ______________________TRACT >/frJ( LOCATION_____________________ SUPT._4 _.4I//- CONTRACTOR EQUIPMENT TEST NO. LOCATION ELEV. OR DEPTH MOISTURE CONTENT % DRY DENSITY P.C.F. % RELATIVE COMPACTION TEST TYPE SOIL TYPE /28 'Q /? Aib A q-1 Y i9 A / /30 -- / 4,d i" 44 42_ OF 41c/,, / tiai 7' ,'Z'e4A, COMMENTS: GeoSoils, Iijc BY: PAGE __________ OF / This field report presents a summary of observations and testing by Geosoils, Inc. personnel only where the tests were performed. Our work does not include supervision or direction of the actual work of the contractor, his employees, or agents. The Contractor should be informed that neither the presence of our field representative, nor the observation and testing by our firm, shall excuse him in any way for defects discovered in his work. It is understood that our firm will not be responsible for job or site safety on this project.