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HomeMy WebLinkAboutSoils & Foundation InvestigationSOILS AND FOUNDATION INVESNGATION SINGLE.FAMILY RESIDENCE LOT 10, FouR MILE RANCH GARFIELD COUNTY' COLORADO GTL ITHOMPSOI.I f Ff ffi TABLE OF CONTENTS SCOPË SUII'IMARY OF CONCLUSIONS SITE CONDITIONS PROPOSED CONSTRUCTION SUBSURFACE CONDITIONS EARTHWORK FOUNDATION FLOOR SYSTEM AND SLABS-ON-GRADE BELOW.GRADE CONSTRUGTION SURFACE DRAINAGE LIilIITATIONS FIGURE I .APPROXIMATE LOCATIONS OF EXPLORATORY BORINGS FIGURE2-SUIUIMARYLoGSoFEXPLoRAToRYBoRINGS FIGURE 3 - SWELL.CONSOLIDATION TEST RESULTS F|GURES4ANDS-EXTERIoRFoUNDATIoNWALLDRAINS TABLE I -SUII¡IIìIIARY OF LABORATORY TEST RESULTS HAGË,MANN BUILÞERS LOT 10. FOUR MILË RANCH CTLIT PROJECT NO' G30¡t451'A'120 1 I 2 2 2 3 4 5 þ 7 I tr ¡ I SCOPE This report presents the results of our solls and bundation investigation for the single-famlly residence proposed on Lot 10, Four Mile Ranch ln Garfield county, Cotorado. We conducted this investigation to evaluate subsurface conditions atthe eite and provlde foundation recommendations for the proposed construction. Our r€pott was prepared from data developed from exploratory borings, laboratory testing, englneering analysis and our experience wlth similar conditions and construction, This report lncludes a description of the subsurface conditions at the site, and presents r€commendatlons for design and construction of foundations, floor systsms, and criterla for details lnfluenced by the subsolls. Construction plans were not developed at the tlme of our investlgation. lf actual building plans differ slgnificanüy from the descriptions contained in the report, we should be informed so that we can check thaf;pr recommêndatlons and design criteria are appropriab. SUMMARY OF CONCLUSIONS t 1. Subsurface conditionE encountered in our exploratory borings conslsted of about 7.5 feet of sllty sandy clay underlain by clayey silty gravel wlth cobbles and lenses of sand and clay. Practical.auger refusal occurred on cobbtes in both of our borings at depthe of l9 and z4leei Èr"" gtound water was not observed in the exploratory borings at the time of drilling. 2. We recommend constructing the residEnce on footing foundationsthat "r" ruppðÉed by the undisturbed, naturalsoils. Gare should be taken to prweït significant wetting of the soils below the buildlng. Design and construcltion crlteria for footings are presented in the report. 3. We judge potentlal for differential movement will be low for slabs-on- gr"å" -"uþported by the undisturbed, natural soils. Additional discussion is in the rePort' 4. Surface drainage should be designed to provide for rapid removal of sudace water alway trom the resldence. A foundatlon drain should be installed around bèlow-grade ereas ln the bullding. HÀGEMANN BUILOERS LOT 10, FOUR MILE FANCH cTLlr PRoJECT NO' G504451'A'l2o 1 ffi SITE CONDITIONS Four Mile Ranch is located east of County Road 117 (Four Mile Road) in Garfield County, Golorado, Lot l0 ls southeast of the lntersection of Red Gliff Gircle and sunrise court. Ground surface on the lot generally slopes gently down to the west at grades of about 2 percent. vegetation on the lot consists of sparse grasses and weeds. PROPOSED CONSTRUCTION Building plans for the resldence were not developed at the time of our investigation, lf constructlon willditfersignificantlyfrom the descriptions below,we should be informed so that we can adJust our recommendations and design criteria as necessary. We understand the proposed residence wlll be a two-story, wood' frame building with an attached garäge. A basement and/or crawl space may be constructad betow the building. similar residences in the arêa are typlcally constructed wlth slab-on-grade floors in basement and garage areas' Maximum foundation excavation depths will likely be on the order ol7 to I feet lf a basement is constructed. Foundatlon loads are expected to vary between 1,000 and 3,000 pounds per lineal foot of foundation wall with maximum interior column loads of 30 kips' completed wall backfill depth may be slightly more than excavation depth as final grades arc adjusted for drainage. SUBSURFAGE CONDMONS Subsurface conditions at the site were investigated by drllling two exploratory borings (TH-1 and TH-z) in thE building envelope. The approximate locations of the exploratory borings are ehown on Flgure l. Exploratory drilling operations were directed by our ffeld representative who logged subsurface conditions encountered in the borings and obtained samples of the soils. Graphic logs of the soils encountered in our exploratory borings are shown on Figure 2' HAGEMANN BUILDERS LOT 10, FOUR MILE RANGH CTLIT PROJECT NO. GS0¡f451'A'120 & ffi Subsurface conditions encountered in our exploratory borings coneisted of about 7.5 feet of sllty sandy clay underlain by clayey sllty gravel with cobbles and lenses of sand and clay. Practical auger refusal occurred on cobbles in both of our exploratory borings at depths of 19 and 24 feet obse¡vations during drilling operations and results of field penetration reslstance tests lndicated the claywas stiff and the gravelwas dense. F¡ee ground water was not obserued in the exploratory borings at the time of drilling. Exploratory borings were backfllled immediately after our field Investlgation was completed. Samples of the solls obtained from our exploratory borings were selected for taboratory testing. onc sample of clay selected for one'dimensional, swell' consolidation testing exhibitEd 0.1 percent consolidation when wetted under an applled pressure of 1,000 psf. Swell-consotidation test results are shown Figure 3 and laboratory teet resutts are summarized on Table l' EARTHWORK We anticipate excavations for the bullding foundation and utilities can be accomptished uelng conventional, heavy-duty excavation equipment' Excavation sides will need to be sloped or braced to meet local, etate and federal safety regulations. We believe the soll at this slte will generally classify as Type B or Type c soils based on osHA standards governlng excavations. Temporary slopes deeper than 5 feet should be no steeper than I to I (horizontal to vertical) ln Type B soils and 1.5 to I in Type G solls. Gontractors should identlfy the soils encountered in the excavations and refer to OSHA standards to determine appropriate slopes' We do not anticipate excavations for foundations or utilities wlll encounter significant amounts of ground water. However, excavations should be sloped to a gravlty discharge orto a temporary sump where water can bE removed by pumping' The ground surrounding the excavations should be sloped as much as practicalto direct runoff away from the excavations' HAGÊ¡UIANN BUILDERS LOT TO, FOUR MILE RANCH CTLIT PROJEcT NO' GS0¡1451'Ä'120 3 ffi Fill may be required to obtain subgrade elevations for the garage floor and exterior concrete flatwork. Areas which will recelve fill should be stripped of vegetation, organic sqils and debris. The on-eite eoils free of rocks larger than 6 inches ln diameter, organic mattsr, and debris are suitable for use as f¡ll. Fillshould be placed in toose llfts of 10 inches thlck or less, moisture condltioned to withln 2 percent of optimum moisture content, and compacted to at least 95 percent of standard proctor (ASTM D 69g) maxlmum dry density. Moisture content and density of fill should be checked by a representative of our firm during placement. properly placed backffll adjacent to foundation wall exterlors is important to reduce inflltration of surface water and subsequent consolidatlon. Backlill placed adjacent to foundation watl exteriors should be free of organlc mettsr, debris and rocks larger than 6 inches in diameter. Backfill should be moisrure condltloned to withln 2 percent of optimum moisture content and compacted to at least 95 percent of standard Proctor (ASTM D 698) maximum dry denslty' FOUNDATION We recommend constructing the residence on footing foundations supported by the undisturbed, natural soils. Care ehould be taken to prevent signlftcantwetting of the soils below the building. our representative should be called to observe conditlons exposed in the completed foundatlon excavation to check that the exposed solls are sultable for support of the designed footings. Recommended design and construction criterla for footings are presented below' Footings supported by the natural soils should be designed for a max¡m-um al iowable soil beari ng press u re qf.19@ Soi le loosened durlng oxcavatlon or the forming process fo-¡-the footings should be removed or re-compacted prior to placing concrete' Continuous wall footings should have a minimum width of at least 16 inches. Foundations for isolated columns should have minimum dimensions of 24 inches by 24 inches. Larger sizes may be required' depending uPon foundation loads' HAOEMANN BUILDERS LOT IO, FOUR MILE RANCH CTLIT FROJECT NO. GS04451-a-l20 1 2. 4 tr Grade beams and foundation walls should be well reinforced, top and UottÀr, to span undisclosed loose or soft soll pockets. We recommend rei nforcement sufficidnt to span an u nsu pported d ista nce of at least 12 feet. Rainforcement should be designed by the structural engineer. The soils beneath exteriorfootings should be protected from freezlng' We recommEnd the bottom of footings be constructed at a depth of at least 36 inchEs betow finished exter¡or grades for ftost Protecton. FLOOR SYSTETII AND SLABS.ON.GRADE Simllar resldenc€s in the erea are typically constructed wlth slab-on'grade floors in garage and basement areas' Based on our laboratory test data and experience, we ¡udge slab-on-grade construction can be supported by the undlsturbed, natural soils with low risk of differential movement and associated damage. some fill may be required below the garage floor slab and exterior concrete flatwork. Flll should be in accordance with the recommsndations outlined in the EARTHWORK sectlon. We recommend the fotlowing precautions for slab-on-grade construction at this site. 3 4. 1. We recommend against placing a gravel or sand layer below elabs because lt increasãs the potential for wetting of the soils below the slabs. Z. Slabs should be separated from exterior walls and interior bearing members wlth slip joints which allow free vertical movement of the slabs. 3. Underslab plumbing should be pressure tested for leaks before the slabs are cónstructed. plumbing and utilitieswhich passthrough slabs shoulJ be isolated from the slabs with sleeves and Provided with flaxible couplings þ slab supported appllances' 4. Exterior patio and porch slabs should be isolated ftom the residence' These slåbs should be well-reinforced to function as independent unlts. 5. Frequent control ioints should be provided, in accordance with American Concreie lnstitute (ACl) recommendations, to reduce problems associated with shrlnkago and curling. Our experience HAGEMANN SUILDERS 5 LOT IO, FOUR MILE RANCI{ CTLIT PROJECT NO. OS0{4s1-A-120 ffi lndicates panele which are aPproximately square generally perform bettEr than rectangular areas. BELOW-GRADE GONSTRUCTION Foundation walls which extend below-grade should be designed for lateral earth pressures where backfill is not present to about the same extent on both sides of thewall. Manyfactors affectthe values of the design lateralearth pressuro. These factors lnctude, butare notlimited to, thetype, compaction, slopeand drainage of the backfill, and the rlgidity of the wall agalnst rotatlon and deflection. For a very rlgid wall where negllglbla or very llüle deflection will occur, an "at-resf' lateral earth pressure should be used in design. For walts which can deflect or rotate 0.5 to I percentof wall height(depending upon the backfill types), lower"active" lateralearth pressures arê approprlate. Our experience lndicatee that typicat basementwalls can deflect or rotate slighly under normal design loads, and thatthls deflection results ln eatisfactory wall performance. Thus, the earth pressures on the walls will llkely be between the "active" and "at-regt" condltions' lf the on-site soils are used as backfll!, we recommend design of below-grade walls uslng an equivalent fluid denslty of at least 45 pcf for this site. Thls equivalent density does not include allowances for sloping backflll, surcharges or hydrostatic pressules. The recommended equivalent density aesumes deflection; some minor cracking of walls mäy occur. tf very littlewall deflectiòn is deslred, a higherequivalent fluid denstty may be appropriate for design. our recent ex{rience indlcates most basement and below-grade walls deslgned wlth 45 pcf to Ü0 pcf equlvalent fluid denslty have performed satisfactorily, Backfillshould be placed and compacted in accordance with the recommendatlons outllned in the EARTHWORK section Water from rain, snow melt and surface irrigation of lawns and landscaping f requenly flows throu g h relatively permeabte backflll placed a djace nt to a resi den ce and collects on the surface of relativety lmpermeable soils occurring at the bottom of the excavation, This can cause wetting of the soils below the building and wet or moist conditions in basement and crawl spece areas after construction. We HAGEIIANN BUILDERS LOT 10, FOUR TILE ßANCH crlll PROJECT NO. 6so{4s1'A'120 6 ffi recommênd provlsion of a foundation drain around belowgrade areas in the building. The drain should consist of a 4lnch diameter, slotted PVC pipe encased ln free draining gravel. The drain should tead to a positive gravity outfall, or to a sump plt where water can be removed by pumping. Typical foundation drain details are presented on Figures ¡l and 5. Ven¡lation is importantto maintain acceptable humidity levels in crawlspeceE. The machanlcal systems deslgnEr should considerthe humidlty and temperature of air, and alr flow volumes, during design of crawl spece ventllation systems. lt may be approprlate to lnstall a ventitation system that is contolled by a humldlstat- SURFAGE DRAINAGE Surface drainage is critlcat to the performance of foundations, f,oorslabs and concrete flatwork. We recommend the followlng precautione be observed during construction and maintalned at alt times after the rssidence is completed: 1 2 The ground surface surroundlng the exterior of the residence should be jloped to drain away from the resldEnce ln all directions. We recomm"nd providlng a slope of at least 12 lnches in the first l0 feet around the rèsidence, where possible. ln no case ehould the slope be less than 6 inches in lhe first 5 feet. Backfill around the exterior of foundatlon walls should be placed in maxi¡num 10 inch thick loose lifts, moisture condltloned to within 2 percent of optimum moisture content and compacted to at least 95 bercent of standard Proctor (ASTtl D 698) maximum dry density. The resldence should be provlded with roof gutters and downspouts. Roof downspouts and drains ehould discharge well beyond the limits of all backfiit. Sphsn blocks and downspout extensions should be provlded at all discharye Points. Landscaping should be carefully designed to minimize irrigation' Plante uéeO-near foundation walls should be llmited to those with low rò¡.t t" requirements; irrigated grass should not be locabd wlthin 5 feet of the foundation. SpriñHers should not discharge withln 5 feet of the foundation and should be dlÞcted away from the building. lmperuious plastic membranes should not be used to coverthe gro "u.t "" immediately surrounding the residence. These membra 3. 4. 5. HAGËMANN BU¡LÍ¡ERS LOT IO, FOUR MILE RANCH cTlll PROJECT No. Gsü451-a'l 20 und nes 7 tr tend to trap moisture and prevent normal evaporation from occurring. Geotextile fabrics can be used to Gontrol weed growth and allow some evaporation to occur. tu Ø¡l'o- L¡MITATIONS The exptoratory borings drltled at the site provide a reasonably accurate plcture of subsurlace conditions. Variatione in the subsuÉace conditions not indlcated by the borings will occur. A representative of our firm should be called to observe subsoils exposed in the compteted foundation excavation to check that the soil are as anticipaþd and sultable for support of the footings as designed. T, This invesggation wdi conducted in e manner consistontwith that level of care and skill ordinarityexercised by engineering geologists and geotechnical engineers currently practiclng under similar conditions in the locality of this project No other warranty, express or lmptied, is made. lf we can be of further sewice in discusslng the contents of this report or in the analysts of the influence of the subsoil condltlons on the design of the structure, please call. cTL ITHOMPSON, lNC.Reviewed by: R Edward R. Wh¡te, E.l. Staff Engineer ERW:JDK:cd (5 copies sent) HAgEMANN BUILDERS tOT IO, FOUR MÍLE RA¡ICH CTIIT PROJECT NO. GS0¡l4sl'A-120 íl a1 { I *üeÞËtIt,LItIIIIIIIoIL+ÊlEIl5\I!aI:I;-TIþËeFeäËfrË\__ItI1süwS-JF.ts,-9CrCI8+4t'E¡*.åi+FoJÊeq$*\t\\Iì\\\\\\\\\\oNFIfFl¡)ttt6oo28Eo-ËräËl5\\\\b,ltl=*{E$cËo\tIItËtJIt\\\IIB.lloEogtITçol9r./€'o tJ-Y-.9trosgVII¡\st TH-1 Tt{-2 0 5 22/12 5o/5 60/s ool¡ È r0 f3 50/1 30/12 20 25 50 J a 1 ProJrct No. GS0445l -A-120 SUMMARY L( ITGEND: NOTES: 1. - Cloy, rtlty, lohdfr rcollcnd grovcl, dflf' Ø ;tplil mot¡r to motrt, ru¡r, brown. (cL m Sfiï¡'ä""J'äI;"ll;,il?i,'$¡,J"*xi'11s molet, ru¡i, brown. (GC-Gll, GIl, sc-sll, st , cL-ìlL) Drfvc ¡qmpl¡. Thc aYmbol 22/12 lndtcolo¡ that 22 blow¡ of o .l40 pound nàmm¡r folllng 50 lnchor wcr1. ruqulrud lo ã¿vc o 2.3 ln-ch O'D. Collfornlo romplcr 12 lnch¡¡. Drlvc ¡ompl¡. Tho rymbol 5O/3 lndlool¡¡ lhot 50 biows of o 140 Pound hommrr tolllns 50 lnahcr wcrc rugulrcd to drlvr o 2.0 lñch O.D. ¡tondord rpllt-lPoon rompbr 5 lncha¡.I îoo þ I T lndlcolc¡ procllcol ¡olld-¡hm qugcr rofuaol. 2. 5. 1, Exolorulory borlng¡ w¡re dt'lll¡d on Fcbruory 2t, zo6s wlth 4-lnch dlom¡hr' ¡olld-¡tom ougcr ond o truck-mounlcd drlll rlg. Explorototy borlngr. r--rrc boakllliod lmincdlqtcly oflar drllllng opcrollonr ?wcrc oomPlolod- Looollon¡ of cxplotutory borfngt ont opprcxlmolc No fru ground wqt¡r wo¡ found ln our axplorotofo borlngr of th¡ llm¡ of drllllng. Th¡sr explorolory borlngr orc rubfoc'l to thr oxpto-nollons, llmltqllon¡ ond ooncluilon¡ ql conlqlnrd ln lhlr rrport. ¡ OF EXPLORATORY BOR¡NGS Ílg. 2 ffi 'î I 5 a 3 0 -f -2 z,ê tt2<tItxluszett,t¡, É,ÀEoo .3 -{ ß € .7 { 0.,| Somple From ,.0 10 APPI.IET} PRESSURE. K$F of ê[,tY, SILTY, SANÞY {CI-ML} HATURAI ORY UMTWEIGHTT T¡l-r ¡f g'FEËT- t'¡nTURALlvtolsruEECoNÍEr¡r* 106 1S.0 100' PCF o/o Swell Gonsolidation Test Results FrG, g \,¡TTJ'OWE NIJtr,I Iil 10N DUE I -l- ÞFlfì ltr¡T r\¡ñ GSn¿d51-À-17{'t FNCASE PIPE IN WASHËí) coNcRrrE AGGrìtGATt (A$TM c3.3, NO. 5/ OR N0. 67) EI:TEND GRAVEL ÏO AÏ LEAST 1/2 HEtGhrT 0F FOOTII'¡G NOTF: ÐRÆN SIIOULD tsE A1 LEAST ? INCHES BELOW ËOI I-OM OF FOOTIHG AT THE HIGHEST POINT AND SLOPL D0|'I|NWARD TO A POSITIVE GRAVNY OUTLËT OR TO A SUMF WIILRI- WATER CAN BF REMOVI.I) BY PUMPING. ü RLINÍ:OIIÇ¡NG STEEL PFR STRIJCTURAL DRAWINGS PROVIDE POSITIVE SLIF .¡OINT BETI,VIIN SLAts AND WALL.. - FLCIOR SIAB __- FOOTING OR PAD PROVIDE PVC SHETTING ËLUID ìO FOUNDATION WALL ÏO RTDUCE MOISTURE PFNETRATION Þilerlor Foundatlon Wall Draln SI OPF PER RTPCJRT I *- gRcKnL[- r [i'if^Hil-""'ä **\ BELOW ûRAOg WALL SLOPE PER 0sHr\ COVER WITH FILTËR FAtsRIC 2" MINIMUM E" MINIMUM OR BEYOND 1;1 SLOPT FROM BOÏTOM oF fro0ï¡Nc. (wHrcHËvER rs Gl,r[AT[R) 4_INCH CIIAMETf,R PIRFORATED DRAIN PIPE lHT- PIPI SI{OULD BE LAID IN A TflFNCH WITH A MINIMUM SLOPE OF O.5 PERCENT. I !l i l ,l I I ! a I c t) I Il ¡ I I PnolGct No. GSO445í -A-1 20 Flg.4 SLOPE 8ËLOW GRADL WALL SLOF'E PER OSHA ÊNCASE PIPE IN }TASHËI) coNcR[rE AGGRECATE (AS'rM cJ3, NO. 57 0R N0, 67) EfiËND ßRAVI- TO AT IF.AST 1/2 tiLlGHT OF FOOTING. -.---- ì,lvllNlMUM E" MINIMUM OR BfYoND 1:1 SLOPE FROM BOTTOM OF FÕOTING, (Y{iltÖHEVER rS GREATFR) PROVIDL PVC SHÊETING GLUËD TO FOUNDATION WAI-I. TO REDUCE MOISÏI'RE PENETRATION. REINFOflCËO STEET FER STRUCTUR¡{. DRAWiNGS *CRAWI _ FOOTINC OR PAD SOTTOM OF EXCAVATION NTÏE: ORAIN SHOULO BE AT I.FÁST 2 INCHES SELÛW SOTTOM OF FOOTING AT TTIE HITHIS] FOINÏ AND SLOPE ÞOWT.IIVARD ÏO A POSTNVE GRAVITY OUTLFT OR TO A SUMP WHERI WATTß CAN BE REMOVTO BY PUMPING. Exterior Foundatlon tfVall Drsln t\- uo.*r,r, -. lcoMPoËrTroht ÀIl0 \ èouplc¡or.¡ pen nuom)l COVER GRAVEL YtlTFr FILTER FAÊÊÍC I i 4_INCH DIAfu{LTËR PERFORATED DRAIÑ PIPE. THE PIFE SHOULD EE PLACED If'I A TRÊNCH W}TH A sLoPE RANüI BETWEFN l/E lNCl{ AT-¡O 1,/4 INCH DROP PfR FOOT OF DRAIN. I ! i SUPPORTED ro .oRåtÈ Projðat No" 980tf4ı1 -A-1 20 Flg. ö TABLE ISUIi,IMARY OF LABORATORY TEST RESULTSPROJECT NO. GSO4¡tltl'A-l 20SOIL CI-ASSIFICATþNCI.AY. SILTY. SA}IDY (CL-I¿!L)PASSINGNO.200stwE{%}SOLUBLESULFATES(Yo)UNCONFINET}COMPRESSMESTREI.IGTH(PSF)EFG LlMlrSPI.ASTICITY¡NDEX(9o)NPATTERIUQUIDL]MIT(%)16SWELL'(%)-0.1I.IATURALDRYDENSITY(PCF)106NATURALMOISTT'RE(%)5.719.0DEPTH(FEEn115BORINGTt't-1Tr-t-l.Note: Srell due to weüing und€r ån applied load of l,üþ psf. Negd¡v€ values indÍ:ate consol¡dd¡on'Page 1 of 1