HomeMy WebLinkAboutSoils & Foundation InvestigationSOILS AND FOUNDATION INVESNGATION
SINGLE.FAMILY RESIDENCE
LOT 10, FouR MILE RANCH
GARFIELD COUNTY' COLORADO
GTL ITHOMPSOI.I
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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
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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
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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
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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
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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
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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.
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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
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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
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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:
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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
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5.
HAGËMANN BU¡LÍ¡ERS
LOT IO, FOUR MILE RANCH
cTlll PROJECT No. Gsü451-a'l 20
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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
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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,'$¡,J"*xi'11s molet, ru¡i, brown. (GC-Gll, GIl, sc-sll,
st , cL-ìlL)
Drfvc ¡qmpl¡. Thc aYmbol 22/12
lndtcolo¡ that 22 blow¡ of o .l40 pound
nàmm¡r folllng 50 lnchor wcr1. ruqulrud lo
ã¿vc o 2.3 ln-ch O'D. Collfornlo romplcr
12 lnch¡¡.
Drlvc ¡ompl¡. Tho rymbol 5O/3 lndlool¡¡
lhot 50 biows of o 140 Pound hommrr
tolllns 50 lnahcr wcrc rugulrcd to drlvr o
2.0 lñch O.D. ¡tondord rpllt-lPoon
rompbr 5 lncha¡.I
îoo
þ
I
T lndlcolc¡ procllcol ¡olld-¡hm qugcr
rofuaol.
2.
5.
1,
Exolorulory borlng¡ w¡re dt'lll¡d on
Fcbruory 2t, zo6s wlth 4-lnch dlom¡hr'
¡olld-¡tom ougcr ond o truck-mounlcd
drlll rlg. Explorototy borlngr. r--rrc
boakllliod lmincdlqtcly oflar drllllng
opcrollonr ?wcrc oomPlolod-
Looollon¡ of cxplotutory borfngt ont
opprcxlmolc
No fru ground wqt¡r wo¡ found ln our
axplorotofo borlngr of th¡ llm¡ of drllllng.
Th¡sr explorolory borlngr orc rubfoc'l to
thr oxpto-nollons, llmltqllon¡ ond
ooncluilon¡ ql conlqlnrd ln lhlr rrport.
¡ OF EXPLORATORY BOR¡NGS Ílg. 2
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Somple
From
,.0 10
APPI.IET} PRESSURE. K$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
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10N
DUE
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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.
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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
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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.
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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