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HomeMy WebLinkAboutPD 2018-0037; FERRI RESIDENCE; FINAL SOILS REPORT; 2019-12-04001 • Geotechnical • Geologic • Coastal • Environmental 5741 Palmer Way • Carlsbad, California 92010 • (760) 438-31 55 • FAX (760) 931-0915 • www.geosoilsinc.com December 4, 2019 W.O. 7536-B-SC ProPacific Builders, Inc. 5631 Palmer Way, Suite D Carlsbad, California 9201 O Attention: Mr. Scott Jaeger Subject: Geotechnical Report of Rough Grading for Building Pad Construction, 1330 Knowles Avenue, Carlsbad, San Diego County, California 92008 References: 1. "Geotechnical Evaluation for Proposed Construction at 1330 Knowles Avenue, Carlsbad, San Diego County, California 92008," W.O. 7536-A-SC, dated February 15, 2019, by GeoSoils, Inc. 2. "Evaluation of Allowable Bearing Value, Active, Passive Pressures, Lateral Press\Jres, and Seismic Design Parameters, 1330 Knowles Avenue, Carlsbad, San Diego County, California 92008," W.Q. 7536-A-SC, dated December 17, 2018, by GeoSoils, Inc. 3. "Improvement Plans For: Ferri Residence, Site and Grading Plan, 1330 Knowles Avenue, Carlsbad, San Diego County, California 92008," sheet 2 of 4, no project no., revised February 2016, by Mountain View Consulting. Dear Mr. Jaeger: In accordance with your request, and as required by the City of Carlsbad, GeoSoils, Inc. (GSI) has prepared this geotechnical report of rough grading for the proposed residential single-family residence. Observations and field compaction testing for this specific construction task occurred between November 26, 2019 and November 27, 2019. Grading was observed and fill was selectively tested by a representative of GSI, on a part-time, as-needed basis. The scheduling of such was solely determined by your field representative. Line and grade was provided by others and not GSI. Unless specifically superceded herein, the conclusions and recommendations in the referenced geotechnical reports prepared by GSI (see References No.1 and 2) remain valid and applicable and should be appropriately implemented during the balance of construction. Purpose of Grading The primary purpose of grading was to mitigate potentially compressible soils within the influence of the planned one-story, single-family residence with a garage and rear patio. Engineering Geology The geologic conditions exposed in excavations during the process of remedial grading for the planned residential structure was observed on a part-time basis by a representative 002 from our firm. Earth materials encountered during grading consisted of existing colluvial soils (topsoil) overlying Quaternary~age old paralic deposits (considered formation or bedrock). Evidence of adverse geologic structure was not obseNed in the earthwork excavations. The site and grading plan prepared by Mountain View Consulting (Reference No. 3) was used as base for the Field Density Location Map (Plate 1). Groundwater Regional groundwater was not encountered within the earthwork excavations and therefore is not anticipated to be a major factor in the future performance of the planned residential structure, provided the recommendations contained in this and our prior reports are properly incorporated into the balance of construction and post-development landscape practices. Due to the nature of the site earth materials, perched groundwater conditions may manifest in the future along zones of contrasting permeabilities and densities (i.e., fill/bedrock deposits contacts, fill lifts, geologic discontinuities), as a result of excessive precipitation, over-irrigation, and/or damaged underground utilities. The potential for perched groundwater occurrence should be anticipated and disclosed to all interested/affected parties. Should such conditions occur in the future, GSI could provide recommendations for mitigation. Geotechnical Engineering Remedial Earthwork 1. Prior to grading, existing vegetation was removed and hauled offsite. 2. During grading, potentially compressible unsuitable soils (i.e., existing undocumented fill, colluvium and any weathered bedrock/formation) were removed to expose suitable formational soils. The depth of excavations necessary to remove potentially compressible soils was approximately ±3 feet below the existing grade. The removal of unsuitable soils was completed to at least 5 feet outside the limits of the building pad, except on the west side where approximately 3 feet was achieved due to adjacent property constraints. 3. Prior to fill placement, the bottoms of the remedial grading excavations (i.e., removals) were scarified, moisture conditioned to slightly above optimum moisture conditions, and then re-compacted to at least 90 percent relative compaction (ASTM D 1557), where tested. 4. All processing of original ground in areas to receive iill, as shown on Plate 1, were obseNed by a representative of GSI. 5. Earthwork was performed to provide a uniform building pad for the planned new single-family residence. Any planned, settlement-sensitive improvements spanning fill/native transitions, and/or located within areas beyond the limits of fill placed ProPacific Builders, Inc. 1330 Knowles Avenue, Carlsbad File:e:\wp12\7500\7536b.gro GeoSoils, Inc. W.O. 7536-B-SC December 4, 2019 Page 2 003 under the purview of this report, will be subject to an elevated potential for adverse soil movement and associated distress, if these conditions are not mitigated in the future. Additional recommendations for treatment of soils in these areas may be provided on request. Engineered Fill Placement Engineered fill materials predominately consisted of the onsite soils derived from the remedial grading excavations. During grading, ~ngineered fills were placed in approximately 6-to 8-inch lifts, moisture conditioned, mixed to achieve slightly greater than optimum moisture conditions, and mechanically compacted to a minimum relative compaction of 90 percent of the laboratory standard (ASTM D 1557), where tested. In general, the thickness of engineered fill placed under purview of this report was generally ±3 feet in depth within and ±5 feet beyond the foundation footprint, where feasible, for the proposed residential structure. Field Testing 1. Field density tests were performed using the nuclear method in general accordance with ASTM test method D 6938-1 0 (Procedure A). The compaction test results are presented in Table i . The approximate locations of the field density tests performed during grading operations are presented on Plate 1. 2. The field dry densities of the engineered fill were evaluated as a percentage of the maximum dry density attained in the laboratory for the representative soil types encountered during grading. Where field density testing indicated inadequate compaction or moisture content, the failure area was reworked until at least 90 percent of the laboratory standard or slightly greater than optimum moisture (ASTM D 1557) was achieved. 3. Field density tests were taken at periodic intervals and selected locations to check the compaction and moisture content of the engineered fill placed by the contractor. Laboratory Testing Maximum Density Testing The laboratory m9-ximum dry density and optimum moisture content for the major soil type encountered during grading, were evaluated in general accordance with test method ASTM D 1557. The following table presents the results: ProPacific Builders, Inc. 1330 Knowles Avenue, Carisbad File:e:\wp12\7500\7536b.gro GeoSoils, Inc. W.O. 7536-B-SC December 4, 2019 Page 3 004 SOIL TYPE MAXIMUM DENSITY MOISTURE CONTl;NT (PCF) {PERCENT) IA -Reddish Brown, Silty Sand I 135.0 I 7.7 I Expansion Potential Expansion testing was performed on a representative sample of site soil, during the geotechnical evaluation of the site, in general accordance with ASTM D 4829. The results of expansion testing are presented in the following table. LOCATION AND DEPTH (FT) I EXPANSION INDEX I EXPANSION POTENTIAL Proposed Building Pad, B-1 @ 2.5-3.5' I <21 I Very Low Saturated Resistivity, pH, and Soluble Sulfates, and Chlorides Laboratory testing indicates that tested samples of the onsite soils are neutral with respect to soil acidity/alkalinity, are moderately corrosive to ferrous metals, present a negligible sulfate exposure, and chlorides were relatively low. Reinforced concrete mix design should minimally conform to "Exposure Classes SO and C1 " in Table 19.3.1.1 of ACI 318-14. It should be noted that GSI does not consult in the field of corrosion engineering. Therefore, additional comments and recommendations may be obtained from a qualified corrosion engineer based on the level of corrosion protection required for the project, as determined by the project architect and/or structural engineer. Conclusions The work performed to date appears to be in general conformance with the preliminary recommendations contained in References No. 1 and 2, GSI field recommendations, Appendix Chapter J of the 2016 California Building Code, and with the grading guidelines of the City of Carlsbad, from a geotechnical standpoint. Field testing indicates that fills placed under the purview of this report have been minimally compacted to at least 90 percent of the laboratory standard (ASTM D 1557), where tested. Based on the observation and compaction testing performed during grading, GSI concludes that the overexcavated residential building pad (see Plate 1 ), constructed under GSI observation and testing, is suitable for its intended use. Unless superceded herein, or as provided in the field during grading, the conclusions and recommendations regarding site construction, including foundation design and construction recommendations presented in References No. 1 and 2 are considered valid and applicable. ProPacific Builders, Inc. 1330 Knowles Avenue, Carlsbad File:e:\wp12\7500\7536b.gro GeoSoils, Inc. W.O. 7536-8-SC December 4, 2019 Page 4 005 Regulatory Opinion of Compliance The engineering geologic and soils engineering conditions present during the process of site grading were observed by a representative from our firm. Based on our observations and testing, the soil engineering and engineering geologic aspects of the construction appear to be in compliance with approved geotechnical reports (References 1 and 2). As such, GSI will certify1 that the soil engineering and engineering geologic aspects of the site plan (Reference #3) are in compliance with the approved geotechnical reports (References 1 and 2), for this project. Limitations The conclusions and recommendations presented herein 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 agreements that may be in place. In addition, this report may be subject to review by the controlling authorities. 1 As defined in the California Business and Professions Code, Division 3, Chapter 15, Article 5, Section 8770.6. ProPacific Builders, Inc. 1330 Knowles Avenue, Carlsbad File:e:\wp12\7500\7536b.gro GeoSoils, Inc. W.O. 7536-B-SC December 4, 2019 Page 5 006 If you have any questions or comments regarding this letter, please do not hesitate to contact the undersigned. TMP/DWS/JPF/jh Attachments: Table 1-Field Density Test Results Plate 1 -Field Density Test Location Map Distribution: (3) Addressee (2 wet signed) ProPacific Builders, Inc. 1330 Knowles Avenue, CarlsbaQ File:e:\wp12\7500\7536b.gro GeoSoils, Inc. W.O. 7536-8-SC December 4, 2019 Page 6 007 Table 1 FIELD DENSITY TEST RESULTS TEST DATE TEST LOCATION NO. 1 11/26/19 East Side Pad, South Center 2 11/26/19 East Side Pad, North Center 3 11/26/19 West Side Pad, North Center 4 11/26/19 West Side Pad, South Center 5 11/26/19 East Side Pad, South Center 6 11/26/19 East Side Pad, North Center 7 11/27/19 West Side Pad, South Center 8 11/27/19 West Side Pad, North Center LEGEND: FG = Finish Grade ND = Nuclear Densometer Ken and Tina Keating 1774 Terraza Street, Oceanside File: C:\excel\tables\7500\7536b.gro.tbl1 TRACT ELEV MOISTURE NO. OR CONTENT DEPTH (ft) (%) 1330 Knowles Ave. 127.9 8.1 1330 Knowles Ave. 127.9 8.4 1330 Knowles Ave. 128.4 8.0 1330 Knowles Ave. 128.4 8.3 1330 Knowles Ave. FG 9.1 1330 Knowles Ave. FG 7.9 1330 Knowles Ave. FG 8.1 1330 Knowles Ave. FG 9.0 GeoSolls, Inc. DRY REL TEST SOIL DENSITY COMP METHOD TYPE (pcf) (%) 124.6 92.3 ND A 126.7 93.9 ND A 122.4 90.7 ND A 122.0 90.4 ND A 127.4 94.3 ND A 123.2 91.3 NO A 127.8 94.7 ND A 125.6 93.0 ND A W.O. 7536-B-SC December 2019 1?~.,,,,c~kt ~ Page 1 008 ~M,f,tfE»SJ:MAAl'SHOt A~rn-ttr,urr I -----! 1 I NJICll.APA.ltCl'l.U,i."HIJ f66/Sot WJG,Uf'NA.'1' -fO(MDf'IRO/f TMX/1:DRCE.,,OS ~tl.V.PN':>.,~ (,) X-3 X-BFG PROPOSED SINGLE STOl1Y RESIDENCE FF•130.S2" PAD EL=129.85 X-6FG ~-X-7FG ~-X-5FG _ -3.0 X-1 X-4 F~~~~:2 PAD EL=1£9.35 KNOWLES AVENUE ~/lCll!l..2,.PA.'ICfi.~HO.fllOW liWlU:~NJl.'I' -\ ____ ..,__Q:oSllNC: ~~~-ll'--------•----KEYNOTES: 0 "tCW 'Stf'AC Jt(SQlJ<~L $CC -"'!CHl!CC,O!'.A., l'VJU, @-a~~ (i} a.)0f Milli COUttl)!»I SV:.TOI {•'II ~) © NlW c:NJU( laM.WiU' ©M.',100t<CRfltl'/.f'°--©10COJ.IIOGNC>fl,a.S££~1'l,f,/ft,, 0~lW)SO,U1.AJ"'tW..'-"',.'T~nt'fitNlll~~'N © Tl;ll(:t,CRf'tD~~~IEW~V..rwt.. (D Nl"W Ql"AH(M KJi1 ~ (l(~. @~~"tl!Wlt/'1'$UIC.ru.."1'l00,.1'0fNf)tf:flfM @ ~~~£5~ ~~~~ @~t'W~JDISCA'llr:£. @"lVG.\Ss:J!'wUf'atS!.'Qit~!IIM'-JIIC'f!S. LEGEND: ..,..,.,_,, c:J OOSIINi:iMJl)VD --•--I.Ill.Jr?'~ ~$",l!f: flAl[R I.W--w--w-~G'-SIW( --•--~Cl)lrif.M,,\11 ---fXIS~(()HT.Mflll: ~occ•.:101.1a -"'41Jfl01~CTIOlf ~ "AS BUILT" 10 I ""'--.,,. __ _ GS/ LEGEND X-4 APPROX/MAT[ LOCATION OF REW DENSITY TtST X-BFG APPROX/MAT[ LOCA 110N OF RN/SH GRADE FJELD DENSITY TtST APPROX/MAT[ DEPTH OF OVEREXCAVA 110N (IN FEET) D APPROX/MAT[ UM/TS OF COMPACT[D FILL PLACED UNDER THE PURVIEW OF THIS REPORT GRAPHIC SCALE 20 I 40 I 80 I ,· = 20· ALL LOCATIONS ARE APPROXIMATE This docvment or efi/e Is not a part of the Construction Documents .and should not bo relied upon 11S being an accurate depiction of design. fru'tfJ~OF CARJ::.51jAb][""""] L.!_J [NGIHl:(IU«IOf,.Al'ITMEMT 4 oo>Atlfi:Kt!Wr ~ · FERRI RESIDENCE 1~~0= ~_,mm~:.~::·.~ FIELD DENSITY TEST ~~ LOCATION MAP Plate 1 ~FJ_ ~, r~~ ~A~~N~lt-------,-----r--~=~~ ~~L_____j[____J W.O. 7536-8-SC DATE, 12/19 SCALE, 1" = 20'