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HomeMy WebLinkAboutCT 72-20; La Costa Vale Unit 3 Lot 431; Soils Report Perliminary; 1987-09-03- - SAN MARCOS ENGINEERING, INC - I I_ 370 MULBERRY DRIVE. SUITE E SAN MARCO5 CA 92069 lb19) 744-0111 CIVII Engmwng . Plmnnmg . Land Developmg . Suweylng . 50115 and Founddton Engmeerr !- , - PREZDUNARY SOILS INVESTIGATIONREPORT ,- i I_ - of Lot 431, Ia Costa Vale No. 3. &p 7950 Carlsbad. California For John Lemkey BY EN(JNEERlNG DEPT. LIBRARY city of carlsbad 2075 Las Palmas Drive C&&Q CA 92009-4859 San Marco9 Engineering, Inc. 370 Mulberry Drive, Suite E San brcos. Ca. 92069 - September 3, 1987 Job Number 87118 j i ,- : /- - ,- ii Mr. John Lemkey 3230 venado Carlsbad, CA 92008 Re: Preliminary Soils Investigation of Lot 431, Map 7950 Carlsbad, California I /- ! / ~- I / I- 4 I- i - Dear Mr. Lemkey, As YOU requested, we have conducted a preliminary soils investigation of Lot 431, Map 7950, Carlsbad, California located at the vicinity of Cadencia and Piragua Streets in Carlsbad, California. Purpose Our investigation was conducted to assess the geologic and geotechnical conditions at and near the site which may affect the proposed development and to gather soils data on which to base foundation recommendations. This report describes the investigation of surface and near surface soil conditions, provides conclusions regarding the resident soils, and makes foundation recommendations for a proposed residential structure. - .- - Project Location and Description - Lot 431 is located at the vicinity of the northeasterly corner of intersection of Cadencia and Piragua Streets, in Carlsbad, California. The lot is rectangular in shape and has been graded sometime in July 1986 to accommodate the construction of a - 1 ! ,- - :- :- :- I I :- j i- I I- / : - c residential house therein. It is proposed at this time to regrade the entire pad for the construction of a residential structure. Plate 1 show the Vicinity Map. Regional Geology Carlsbad, California lies on the coastal plain of northern San Diego County and the adjoining low rolling foothills of the Peninsular Range of Southern California. Marine conglomerates, sandstones and shales of Eocene to Pleistocene age underlie the coastal plain while metasediments and metavolcanics of the Santiago Peak Formation intruded by Cretaceous batholithic rocks make up the foothills. Lot 697 is underlain by a northwesterly trending belt of the Juro-Triassic Peak Formation which consists of metavolcanic and metasedimentary rock. Although a number of small faults have been reported in the surrounding area, none are known to be active. The nearest known active faults are the Elsinore Fault Zone located 24 miles to the northeast and the offshore extension of the Rose Canyon- Newport/Indlewood Fault Zone which lies from 6-8 miles offshore beneath the Pacific Ocean approximately 10 miles to the southwest. Both faults have been active in recorded history and are acknowledged of being capable of producing earthquakes up to Richter Magnitude 7.0 (M7.0). Soils Investigation Four (41 test pits were excavated at site at the approximate locations indicated in Plate 2. The test pits are indicated as - 2 Lemkey Geotechnical Investigation, cont'd... I- i_ - , : i-, i ! -. ‘_ -1 .d .- T-l to T-4, inclusive. Log of the soil samples encountered are shown in Appendix b. Findings The fill material imported to form the existing graded pad consist of brown to light brown silty sand. The native soils is brown to reddish brown sandy clay with broken or fractured rock. At test pit T-l, very hard, dense rock fracture was encountered at bottom of test pit at -- 3.5 feet. At T-2, native reddish brown clay was encountered at -- 4 feet from existing surface, while at T-3, the reddish brown Sandy Clay material was encountered at -- 7 feet below surface. The fill material overlying the graded pad was compacted and 13 tests were taken at the locations indicated in Plate 1. The test results are shown in Appendix B. Laboratory Soils Testing Maximum dry density test of the prevailing fill material was made and the test result is shown below: SAMPLE T-l @ -2.5': Brown Silty Sand MAXIMUM DRY OPTIMUM MOISTURE DENSITY CONTENT 127.5 pcf 9.6% Expansion Index Test per UBC Standard No. 29-l indicate the soils to have an E.I. of 48 which is of low potential expansion. - I - Lemkey Geotechnical Investigation, cont'd... i- ;- - - .- - - - : - I/ I- Conclusions and Foundation Recommendations - 1. It is our opinion that the existing site soils can safely support the project proposed to be constructed at site provided the recommendations presented herein are observed and followed during the design and construction of the structure proposed to be built. 2. The Earthwork Specifications found in Appendix A forms part of these recommendations. If there are conflicts in the provisions between the Earthwork Specifications and these specific recommendations, the latter provisions shall prevail. 3. We recommend an allowable soil bearing pressure of 1500 psf for standard spread footings. Bottom of footings should be at least 24" below adjacent finish grade or natural grade. 4. All exterior and interior wall footings should be continuously reinforced with 2 -#5 bars placed 3" above bottom of footing and 2 -#5 bars placed 2" below top of footing. 5. Concrete slabs on grade should be at least 4" thick and reinforced with welded wire mesh placed at mid-thickness of slab. The slab should be underlain by 4" sand and vapor barrier. Prior to placing the sand and vapor barrier, the subgrade soils should be wetted to at least 4% above optimum moisture content. 4 ,- Lemkey Geotechnical investigation, cont'd... , ,- 1_ 1.- i 1 I- - ! ’ - 1: I i : - 1, - I. .-. I. .- I, .- - I. - 1. 6. 7. a. 9. 10. 11. The following soil parameters are recommended for use in the design of retaining walls: Active equivalent fluid pressure = 36 pcf, No surcharge backfill Active equivalent fluid pressure = 59 pcf, 2:l slope backfill Passive Equivalent fluid pressure = 330 pcf, No surcharge Passive Equivalent fluid pressure = 164 pcf 2:l Backfill slope Coefficient of friction between soils and masonry = 0.33 To minimise differential settlement inherent in cut and fill situation of graded pads, it is recommended that the pad soils in the cut area should be undercut by 36 inches. A soils engineer should inspect the foundation trench soils prior to poring of concrete for the footings to see to it that the recommendations presented herein are followed. Recommend slope ratios for cut and fill not to exceed as shown: cut: 2 horizontal to 1 vertical Fill: 2 horizontal to 1 vertical All surface water runoff should be directed away from the foundation system positively. This firm should be contacted if soils different from the soils presented in this report are found at site during the grading and construction operations so that a proper 5 I /- - Lemkey Geotechnical investigation, cont'd... evaluation and recommendations of the soils can be made. Limitation of Report - This report is based upon surficial and limited subsurface observations and logical projections inferred from observed conditions. Should conditions varying from those reported be found during development, a qualified soils engineer should inspect the site and evaluate the potential effect of our recommendations. The report has been prepared in accordance with generally accepted soils and foundation engineering practice. No other warranties expressed or implied are made as to the professional advice and recommendations contained. This report is provided for the exclusive use of the client or his authorized agents. Should you have any questions regarding this report, please call us at 744-0111 and mention Job #87118. Very truly yours, ENGINEER1 6 .- Lemkey Geotechnical Itivestigation, cont'd... Enclosures: - i Appendix A --Earthwork Specifications Appendix B --Boring Logs & Laboratory Test Results I /_ Appendix C --Unified Soils Classification System Plate 1 --Vicinity Map 1’ Plate 2 --Test Pit Location i- - 1; I- 1’ .- I : I. i - 7 .I /- I I j- - I !- j- I- I- i i- I I- i /_ j- I r I > I_ I - - - , - - APPEUDIX A RECONNENDED EARTHWORK SPECIFICATIONS .- - /_ APPENDIX A RLCONHCNDLD EARTHWORK SPECIFICATIONS I- I l- -. :- - 1. WEEBb&, Qg$~fi~er~Q& The ob]ective ie to obtain uniformity & adequate internal strength in filled ground by proven engineering procedures and teat.3 ao that the proposed atructurer may be safely aupported. The procedures include the clearing and grubbing, removal of existing atructuree, preparation of land to be filled, proceaaing the fill aoils, filling of the land, and the spreading and compaction of the filled aream to conform with the linea, grades, and elopea aa ahown on the approved plans. The owner shall retain a Civil Engineer qualified in Soil Mechanics (herein referred to a.s Engineer) to inspect and teat the filled ground am placed to verify the uniformity of compaction of filled ground to the specified 90 percent of maximum dry deneity. The Engineer shall advise the owner and grading contractor immediately if any unaatiefactory conditions are obeerved to ericlt and shall have the authority to relect the compacted filled ground until such that aa corrective reaaurea are taken, neceaaary to comply with the apccificatione. It ehall be the sole reaponaibility of the grading contractor to achieve the specified degree of compaction. 2. ELfb!?Z!!4,. 48L!mxwL A!!D eeEPdK!G !mM TO BE E&LED, (a) All brush, vegetation, and any biodegradable refuse shall be removed, piled, and burned or otherwise diapoaed of ae to leave the aread to be filled free of vegetation and debria. Any unconpacted filled ground or loose conpreeaible natural ground, ehall be removed unleaa the report recommenda otheruiee. Any unstable, -w-w, or otherwiee uneuitable areaa ahall be corrected by draining or removal, or both. , - 1' SAN NARCOS ENGINEERING civil, foundationa L roilr , I - , (b) Thr n.tur.1 ground which ir deterrined to be satinfactory for the eupport of the filled ground rhall then be plowed or l cerified to . depth of et 1ea.t .1x inchem (6") and until the aurfacr if free from rut., hueeock., Ar other uneven feeturer which would tend to prevent uniform coepection by thr equipment to be med. Cc) After thr n.tur.1 ground he. been prepered, it l h.11 then be brought to the proper 8oieture content end compected to not leer than 90 percent of maximum denelty in l ccordence with the A.S.T.M. Dl657-70 method which Il... 26 blowr of m 10 pound rammer felling 16 inche. on l ech of 5 lmyera in . 4-inch diemeter l/30 cubic foot cylindricml mold. (d) Where fillr l re med. on hillmidem or exposed rlop. areaa, with gredirnt. greeter then 10 percent, horizontrl bmcher l h.11 be cut into fira undimturbed n.tur.1 ground in order to provide both later.1 and verticel l tmbility. Thir la to provide . horizontal bar. l o thet l ech lmyer i. plmced and compacted on l horizontrl plane. The initi.1 bench at the toe of the fill l h.11 bo at learnt 10 feet in width on firm undirturbed neturml ground at the elevation of the toe l tak. plmced et the n.tur.1 engle of repose or design alope. The Engineer mh.11 deterrinr the width and frequency of l ll succeeding benchem which will Vary with the mail conditiona and the mteepnemm of elope. 3. "4~~~~~L",o~~S,t"egQX4~ ECQYXBLHEITPr The fill l oilm of melect mmterielm ire0 from vegetable matter, and other deleteriour rubmtance., and mhall not contein rock. or luapr greater than 6 incher in dimeter. Thim mmy be obtained from the excwation of bmnkm, borrow pit. or any other approved sources and by mixing moilr from one or more l ourcea. If l xceaeive vegetation, rock., or l oilr with inadequete mtrength or other unmcceptmblr phyricel chmracterimticm are encountered, theme mhmll be diepoaed of in uaate area am mhoun on the plan. or aa directed by the Engineer. If, during grmding opermtionm, l oilm are found which were not encountered and teated in the preliminary invertigmtion, tertr on theme roil* rhall be performed to determine their physic.1 cheracterimtic.. Any special treatment recommended in the preliminary or aubaequent moil reporta not covered herein ah811 become an addendur to these ap~cificatiOnm~ 2' SAN RARCOS ENGINEERING civil, foundations k aoilm - !- I ! :- - ;;,ELAQZML ~EEEAPIMQr CMP EQMOKIIMP L&L MbIEEIbLP+ When the roiature content of the fill material ia belou that rpecifird by the Engineer, water mhall be 8dd.d in the borrow pit until the roirturo content im near optimur to l mmuro uniform mixing and effective compwtion. (b> Whrn the moisture content of the fill material ir above that l pecified by the Engineer. rcwlting in inrdequate compaction or unstable fill, the fill material ahall be aerated by blading and scarifying or other l atirfrctory methodm until the moisture content im near optimum am specified. (c> After proceraing, the auitabl. fill material rhall be placed in lryerr which, when compacted, ahall not exceed dX inchem (6" ) . Each layer ahall be spread evenly and rhall be thtoughly mixed during the apremding to ensure uniformity of material and moisture in each layer. (d) After each layer haa been placed, mixed and spread evenly, it l hmll be throughly compacted to not lemm that the deneity art forth in paragraph 2(C) above. Compaction -hell be accomplished with aheepafoot roller*, multiple-wheel pneumatic-tired roller*, or other 8pproved type. of comp8ction equipment, much . . vibrmtory equipment that im l pecially designed for certain mail typm. Rollerm ahall be of much design and maintained to much a level that they will be able to compact the fill materiml to the specified density. Tamping feet of l heepmfoot follere ahall be maintained 8uch th8t the SOil will be compacted rather than aheared by the roller. Rolling ahall be accomplished while the fill #aterid im at the specified moisture content. Rolling of l rch layer l hmll be continuour over itr entire area and the roller *hall mmk. mufficiint tripm to inmure thmt the specified density haa been obtained. Rolling ahall be l ccorplimhed in l planned procedure much that the entire aream to be filled ahall receive uniform comprctive effort. (e) The rurfmcer of the fill l 1op.a rho11 be compacted by *e*nm of mhaepmfoot roller8 or other suitable equipment. Compacting operationr ahall be continured , - - 3' SAN RARCOS PNCINEERINC civil, foundation. I moilm - !‘- i- appreciable l mount of loore aoil on the dopea. Compacting of the rlopem rhall be l ccompliahed by backrolling the l lopem in increments of 3 to 5 feet in elevation gmin or by other rethodr producing l 8timfactory rerultm. (f) Field denmity temt. mhall be taken for approximately each foot in elevation gain after compaction, but not to exceed two feet in vertical height between teetm. Field density tertm l my be taken at interval8 of 6 inchem in elevation gain if required by the Engineer. The location of the teatm in plan l hall be M apaced to give the bemt pommible coverage l nd ehall be taken no fmrther apart than 100 feet. Temtm rhall be trken on corner and terrace lotr for l rch two feet in elevation gain. The Engineer may take additional tertr am considered neceamary to check on the uniformity of compaction. Where aheepmfoot rollera are wed, the temtr ahall be taken in the corpected material below the disturbed surface. No additional layer- of fill rhall be l premd until the field density temta indicmt. that the rpecified density haa been obtained. (cl) The fill operation ahall be continured in mix inch (6-j comp8ct.d leyerm am rpeciffed above, until the fill ham been brought to the finished slopem and gradem me mhoun on the mccepted plmnm. Sufficient inspection by the Engine+r be l aintmined during the filling mnd compacting operationm mo thmt he can verify that the fill V.. constructed in accordance with the accepted mpecificrtionm. 6. a,a,~nrl L&RILr No fill material ahall be placwiL spread, or rolled if weather conditionr increase moisture content above permirrible limitr. When the work im interrupted by rain, fill operationm mhall not be remumed until field teatm by the l 0ilm engineer indicate that the moisture content and density of fill are am previously apecificd. , - I !- SAN UARCOS ENGINEERING civil, foundation. k aoile /- .- 7 8;il~&B&~hl !!&NM Qg !!Q!!,NQ~ndY# PQihr Thorn. that expand 3.0 percent or leea from 8ir dry to axturmtion under l unit load of 150 pounda per rqu8re foot are con8idered to be nonexp8neive. 8. All recommendation. prexented in the attached report are e pert of there rpecificetione. I- 1 1 ! i- , I- I - , - 5 ’ - - I- i- I I- i - - APPENDIX B LABORATORY TEST RESULTS . - - ! a_- j- i ,~ ! . f a- j- /- ,- .- , - SAN MARCOS ENGINEERING ClWL C*01”1..*. ,QIL. . ro”~D-.lo” ,a0 UUL.,.l o..r*. .“... . Boring ?40.7= ..l “..55.. 5. .a<.. x.*eu 7...0111 Sheat NO.- of- CCNTRACT NO. PGRPCSE 5T,&a?s7H Ma!arial / i- - SAN MARCOS ENGINEERING j- ‘, ~~ I (.- , \ / i- 1 I- I- CWlL ChO.W‘I... set&.. . c*“..o.llo” so0 “UC...-- o-r*. .r.-. . *r-d “..CS.. c- .a<.. ..,s, ,...o,,, Peal No./ofL CONTRACT NO, PURPCSE Ua!arial 6 RenarkI - SAN MARCOS ENGINEERING - :/I :! .f /-- . 1’ ;I- / ‘- I - i I :- j ! i - , - i Cl”lC C*Oi..sl... SQIL. . ,OcI..O..10~ 3ao UVL.E.I o.,r*. ..d-. . &ring No. F3 ..” -..cc.. 5. .a.?.. s.,e, ,...011, Seat No.+of~ LEMKEY ,4E5.0@~,%=q.%RSt, Lt h7a CCrUTRACT NO. PL’RPCSE J Ua!erirl 6 Remarks j- i- s- !I- II-~ jl- I IL i . ii jt i jj .i i 1 ;i iNi // jl ip j i :l - , i I SAN MARCOS ENGINEERING CWlL c-a,-**... SOIL. . roY..o.~\o~ ,a0 ““L.E.I O.,“.. .I,.. . Boring NO. H ..s. “..CG.. 5. *a=.. ,.,v, ,r..o*,, She! N../Of~ CChtTRACt NO. PGRPCSE d Uararial 6 Renarkr I jl ! : : 1 - I- I, ,. i i ,~I> SAN MARCOS ENGINEERING, INC. Job No. 87/F 370 MULBERRY DRIVE. SUITE E Lc%zkey SAN MARCOS. CA 92069 Project: (6191 744-0111 , ~heMf2J ' Sample ID; Dry Density vs. Water Content Curve. Test Per ASTM D1557-78 &lculated_: Maximum Dry Density: /*5pc1 Optimum Moisture Content:?k 1 I 150 100 , .- 9 12 16 20 24 Water Content, Percen.t Page I l- Sumlnarr og T.cC :- i- i i- lr I i TEST ---- N!c!!!ER 1 2399 2 +_401 3 502 4 +405 5 +_410 6 2412 7 2408 a +408 9 2416 10 t419 11 2413 12 2387 13 2400 APPROX ------z L?EY -------- RELATIVE l??n&lUES ELEVA- DENSITY COMPACTION ------ ___-___ ---------- TION(FT) (PCF) (%> -------- ----- --- 121.07 93.1 DriVeWay 120.82 92.9 Pad 122.42 94.2 Slope 127.17 97.8 Pad 109.20 92.5 pad 120.00 92.3 Pad 118.65 91.3 Pad 120.64 92.8 Pad 115.12 91.6 Pad 120.91 93.0 Pad 124.21 95.6 Driveway 110.32 85.0 Slope 111.77 86.0 Slope ,- I I- , I - I !- I_ i I- 1 1 ; ,- - I- j - I /- I I- /- / i ;_ I - - - , - APPENDIX C UNIFIED SOILS CLASSIFICATION - . \ A*DcLln*Y I- - i ~~ ! I -i ,’ ! I : I-- j 1 i- ! 5 i- -~ .- 4 - nrrrl.“rn ” UNIFIED SOIL CLASSIFICATION SYSTEM MAJCR UVISIONS LETTER sw3a MscAIPT0NS GRAVEL 1 GW ~LCU,~ 6- 5-"-m.- Hue COARSE AND CLEAU QQAVEL~ bwNLU, LITTTU bu Lp ruea. GRAINED GAAVELLV GP -LY.u*?w cuvnr. -vrL-yY? SOILS SOILS %=fY - WC’CW, Inn* oa ta ~~. cwtmusaf: YLTY l MVC.S oum-SW8 a ctiam -PAZ. m-r rrl*nard cum *-ma, cum-mrl SILT n-. L SAND sA3SlU QEAH SAmS SW uu-ChAme wu7s,o&wsuv w*iTwdm 2 $lll pro, crr-fu on 10 rlb4m b-M& on bm ,y*GFG$* 1 ’ ‘SF+ ~~;‘~~~y&..~:a~’ b-afLIIw8ao)j~ - ;p!s8+z w%%Es , su a&TV na#m, *;LI*-*ILT MRlvCd tw~~YL+*H8 Anu~T Y ma%) SC cuI1* uwm, yo-urn UKri-f Dwk LLW, 44 rer* w8 FINE SLls Y CR&NED Am LIaJo LIMIT sots am LESS THAN so hG+2NucLM w w -8 raw CL X~i;*S!%fYfi Yt a OICY ,I* w arc SILT' we m rumrGT YH LIGUO LYIT iz?cxs-~ zs;;c,“,J,“,, GREATER CH Uo~rY rLms --uww l ee- 3 wmt THAN so -’ I OM : ~&K,,~&M~~L~ * HIGHLY’ ORGANIC SOiLS l f M,tu*sw~Km# MM a-k cwmrl b@lv: ALY oIMc5 Wmz4TC -IYI asn. CLAanln3CAr c3) FEV TO SAMPLE MTA DEPTH QI ELtVATlUt(FEET) . l ‘. tt INMCATES PUSED) SArnE REccHERl SAMPLER rVPE 6RARilC LOO m - S INCH SPLIT LETTER SYMBa FOR TUBE SAMPLER SOL. TYPE Tw - 3 INQl THIN WALL OlSTlNCT CONTACT ‘_ SAMPLER BETWEEN SOIL STRm ST - 2 INCH WIT lL6E SAMPLE8 Gd?AOJK .CHANGE c -ROCK CORE- BETWEEN S’3L STRATA. b . - R&~KKR~STURBED ’ KJTTCM ff BORINO ~~..~___ __~~ I _- -.-. -.-~-.. - -~~ - - _ _ _ _ _ _ _ _ . ,,..lL,e- I-. - .- - SAN MARCOS ENGINEERING Civil Engineers 380 Mulberry Dr. Suite E SAN MARCOS. CALIFORNIA 92069 ~ (619) 744.0111 L- J ---_---i-*-------e I\ 1, - -.. j I I r I I -..;-: 1 , 1 I / f-Y’