HomeMy WebLinkAboutSubsoil Study for Foundation Design 06.26.2015¡\,'- ,:i
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June ?$. 201 5
Jostu Eìlis
44;8ç i{ighivay 6
ülenw*ad Springs, CcT*rado 816ûi
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Subj*ct;
J<lb Nc. 115 lió¡t
subsoil study forFonndation Design. proposetl shop Euilcti'g
Åpprcximately 1500 cauntyRoatJ z4t {EasÊ EIk cråek Road}, Galfielrt
Count5r. Colorado
Dcar Mr. Ellìs
,{s r*quested, Heprvcrtãr-Pawlak Geotecl¡nica}u Inc" perfonned a subsoil study fgr tlesig;r
*f fe¡undatiofi$ trt the subject site- 'l'he sfildy lvas conclucted i:r accordançe with +ur
ågreÊrueJlt for gectecirnical engineering services tr y+u dated ,4pril ?, 201s. Thc data
ûhtainerl and or¡r reeornmendntians b'ased on the proposed construetion anrl zubsurfae*
çandifiCIns eRcnu¡rterec-¡ *r* presentrd in tkis r-ep*d.
Frop*sed C*nstruetian: 'Ihe prÕpos*cl shop buiirling witl be a single stary pole barn
lc+ated c¡il the site as sht)wn on Figure 1. Grcund floar will be slab-cn*grad'e. CÆt d*ptlis
xre expected to tange iret-lveen abcnt I fo 4 tbet. Foundation ioadings f-or this type of
c*nslructian are assurnËrl tc be relatively light and ïypical r:f tl¡e pr-opcsed t5,pe cf
cçnstruction.
If building can¡liti*ns Ðr frrutrdatir:n lcaclings arn sÍgnifîcantiy differer:t åam t¡ose
elescrilie¡l :rbÛr'e, we shauicl b¿: notifi*rl to r-s*valuate Èhe ieeommeinlations pîesented jn
lhis report.
$åte Cauditionsl Th* site is r.acaltt ¿ruii ths gt'aunci surface has be*¡: gr.*eted with mln*¡:
r:r¡ts ¿¡fid iill. Tl:e graund surface siopes cÌ*rvn to the u¡est eit *boirt Z tc 4.çá. TIie sitç is
vېetate{: with gress atld rvcecls. A cfry tirainage is l*eaied s*uth of the sl-rcp building.
S¿rhs¡r*.thce Cs¡r*iåi+lrs: The "çubsr¡rtbce cr¡nditj*ns at the site rverc çv-?luated by
*se::r'aåi*g t"vo explorat*rv pits at thc appr*xitnatc lo,*:åtians sh*r.vn on Figure l. Tfun
i*gs of the pits are pres**l*d on Figrir* 2. Th* subssitrs Ðn$r]u11rr1ïûil, hçl:ç abnut ? fect
cf fill ai Fit I ¡rnd 6 inch*s *f t*pserii ¿t Fit f. cansist*cl ¡:{l*açc silty sand ia.irh se*ft¿r*d
glavel *i¡d ccbbles. TIte sanrl soils beeei*re slightT¡'*ilt5'u,.iih d*pth a::ci *,xtei.:sl*r1 iJ-o:¡11 tr¡
:...,: .,.4: t.l- i..
;, .. i
rt
the pit depths of 6Y¿ and 7 feet. Results of swell-consolidation testing performed on
relatively undisturbed samples of siþ sand, presented on Figures 3 and 4, indicate low
compressibilityunder existing moishre conditions aud light loading and a low to
moderate collapse potential when wetted and under additional load. The samples were
probably partly disturbed. The laboratory testing is summarized in Table 1. No fiee
water was observed in the pits at the time of excavation and the soils wcrc generally
moist.
FofficFnmn¡neÉrw Considering the subsoil conditions encountered in the
exploratory pits and the nature of the proposed constuction, we recommend spread
footings on the undistmbed naturfll soil for an allowable
psffor support proposed shop building. The soiis tend to compfess
wetting and there could be some post-construction foundation sefflement.
Settlement of I to 2 inches could occur depending on the for¡ndation loadings depending
on fhe depth and extcnt of the wetting.
Footings should be a minimum width of i8 inches for continuous walls and 30 inches for
columns. All fill, topsoil and disturbed soils encouutered at the foundation bearing level
within the excavation should be rernoved and the footing bearing level extended down to
the undishrbed natutal soils and the subgrade compacted. Exterior footings shouid be
provided with adequat$ cover above their bearing elevations for frost protection.
Placement of footings at least 36 inches below the exterior grade is typically usecl in this
area. Continuous foundation wails should be reinforced top and bottom to span local
anomalies such as by assuming an unsupported length of at least 12 feet. Foundation
walls acting as retaining structures if any, should also be designed to resist a lateral earth
pressure based on an equivalcnt fluid unit weight of at least 50 pcf for the on-site soil as
backfill. A representative ofthe geotechnical engineer should observe all footing
excavations prior to concrete placemeut to evaluate beadng conditions.
Flaar Slabs: The natural on-site soils, exciusive of topsoil,are suitable fo support liehttv
loaded. slab-on-construction. To reduce t}e effects ofsome differentiai movement,
floor slabs should be sepårated from all beming walls and columns with expansion joints
which allow unreskained vertical movement. Floor slab conkol joints should be used to
reduee damage due to shrinkage cracking. The requirements for joint spacing and slab
reinforcement should be established by the designer based on experience and the intended
slab use. A minimum 4 inch layer of road base gravel should be placed beneath slabs for
suppolt and to facilitate draÍnage. Tlris material should consist of minus 2 inch aggregate
rvitir less than 50% passing the No. 4 sieve and less than 12% passing the No. 200 sieve,
All fiii materials f.or support of flaar slabs should be compacted to at least g5% of
maximum standard Proctor density at amoisfure content near optirnum. Required fill can
consist of the on-site soils devoid of vegetation, topsoil and oversized rocks.
1
Job No. I 15 ¡36Á'
eåEtecn
-3-
Undcrdrsin System: It is our understanding the finished floor olevation at the lowest
level is at or above the sutrounding grade. Therefore, a foundstion drain system is not
required- Sle recommend below-grade construction, such as retaining walls, anrl
basement areas, be protected from wetting and hydrostatic pressure buildup by an
underdrain and wall drain system.
If the finished floor elevation of the proposed structure has a floor level beiow the
surrounding gadq we should be contacted to provide recommendations for an underdrai:r
system. All earth retaining structures should be propedy drained.
Surface DraÍnage: Þositive surface drainage is an important aspect of the project to
prevent wetting of the bearing soils. The following drainage precautions should be
observed during.construction and maintained at all times after the shop building has been
completed:
1) Inundation of the faundation excavations and underslab areas should be
avoided during conskucti on.
2) Exteriorbackñll should be adjusted to near optimum moisture and
compacted to at least g5% of the maximum standard Proctor density in
pavement and slab areas and to at least 90% of the maximum stanclard
Proctor density in landscape areas. Free-draining wall backfill should be
capped with about 2 feet of the on-site, finer graded soils to reduce surface
water infiltration.
3) The ground surface surrounding the exterior of the building should be
slopecl to drain away from the fourdation in all directions. 'we
recommend a minimunn slope of 12 inches in the first 1ü feet in unpaved
areas and a minimum.slope of 3 inc,hes in the first 10 feet in pavement and
walkway areas.
4) Roof downspouts and drains should discharge well beyond the limits of all
backfill.
5) Landscaping which requires regular heavy irrigation should be located at
least 5 feet ûom the building.
Limitations: This study has been conducted in accordance with generally accepted
geotechnical engineering princþles and practices in this area at this time. We make no
warranty either express or implied. The conclusions and recommendations submitted in
this report are based upon the data obtained from the exploratory pits excavated at the
locations indicated on Figure 1 and to the depths shown on Figure 2, the proposed tlpe of
construction, and our experience in the area. Our services do not include determining the
presenter prevention or possibility of mold or other biological contaminants (MOBC)
developing in the futu'e. If the client is concerned about MOBC, then a professional in
this special field of practice should be consulted. Our findings inclurle interpolation and
Job No. I 15 136A
GeFtectl
-4
e;'rh:allolâtitn r:f th* sul¡stirt'aee contlition* iclentifîed at the explor..atoly pits a¡cl !.a*atio¡:s
i:r fhe sr¡h¡;r¡rface eandilictrs nraS'' ¡r¡t beccme evidr.nt l¡ntil exeavati*n is perfor¡necl. {f
cÚncfiti*ns encountered *.luring consLnrcti*n nppeaË difïerenf fi:am those described in this
rtFûrt, rve shoulil be ¡rotitied at {¡ncc sù ¡e-cvalr¡ation of the reconunerrdatiüns rtay be
nradc.
"I'his repott ltas been pleparecl lor ihe exclusive use by our *lie:rt lar desigr purp*ses. Wg
¿r"e Rot respansihle fi:r technical ilterpretatians hy othei-s of our i¡frrr¡n*tian. As ihe
project evolves, n'e shoulcl pt'or.ide cantinried c*nsult¿:tlon a¡rl lieklservices rluring
*orrstrcctiort tc l"evie'nv and. n-lol.¡iior the implerlelrtatio¡r nf arr ler:ornrrendations, an¿l to
verity that tbe recomme¡rdatìilns have been ap1:ropriately inferpreted. Sigrificagt clesigir
changes t-nay rec¡uire adclitional anal}:sis sr modilÌcatinns ta the reeorm¡enelaticns
presenterl hetteiü, !Vr. reeom¿rend on-site cbse¡'vafic¡r of excayations al:d lbunriation
beari'ng straT¿r and testing oI sil.uctur*] fìll by a re¡rresentatìr'e of the geltechnicirl
crrgineer.
I{'you hat'e auv tlueslions or if ç.erna¡r be alfurther rlssistance, please let *s kaorv.
tr{espeelfu I ly Su [:mitted,
HEPI4/ÛRT'H . PAI,VLA I{ GEÛTË CHNI*Á I., 15: {].
Li:uis trller
R*i.ierved try:
llaviil.4. Yonng. P
LE'F¡iltsrv
alT¿=rchnrents F-ìgure Ì -Fxploratory Fit*
Figure ? - f.,ogs *lEx.p1r:i-ator-v Pit*
Fìgur:es 3 ;rirr{ 4 - 5r+.ellCunsoli¿1¿r"tiun T**qt Resuli
Tr¡bl* T : $un-lr*ary *f L.ri:r:raror1. T'*stìng
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.luh ï*. I l-! f .ifì¡\
+aÞ#*drf.e.;h
TCI COUNTY
ROAD 241
NOTTO SCALE
POND
APPLE TREES
PIT 1
I__->
HILLSIDE
HILLSIDE
---------l>-t
-(Jt'-o
Iâ
PROPOSËD
POLEBAHN .<-
O
oæF
95o
--t¡-.
È*--
I
PIT 2
364115 1 LOCATION OF EXPLORATORY PITS Figure 1
PIT 1
ELEV.: 100'
PIT 2
ELEV.: 102'
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LEGEND:
WC:11.1
DD:90
-ã)0=33 WÇ=15,4
DD:82
WC=11.9
DD=92
FILL; manplaced clayey silty sand and gravelwith cobbles,lorsê, moist, grey, some debris.
TOPSOIL; organic silty sand, moist, dark red-brovr¡n.
10
5
10
SAND (Sil¡T); silty to slightly sílty with depth, scattered graveland small cobbtes, loose, moist, red-brown.
2n Diameter hand driven líner sample.
Disturbed buik sample.
NOTES:
1. Exploratory pits were excavated on April 18, ZOIS with a backhoe.
2- Locations of oxploratory pits were measured approximately by pacing from foatures shown on the sito plan
provided.
3. Efevations of exploratory plts were rneasured by hand level and refer to the Bench Mark of ground surface at pit i
with assumed elevation of 100,. Pit togs are drawn to depth.
4. The exploratory pit locations and elevations should be considered accurats only to the degrse implied by the method
used.
5' The lines between materiafs shown on thc exploratory pit logs represent the approximate boundaries between
malerial types and transÍtions may be gradual.
6. No free water was encountered in the pits at the time of excavating. Fluctuation in water level may occur with time.
7. Laboratory Testing Results:
\¡tlC = Water Content (%)
DD: Dry Density þcg
-200 : Percent passing No. 200 sieve
Effi
WÅ
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115 136A LOGS OF EXPLORATORY P|TS Figure 2
0
1
2
3
4
Â
7
c
^octutoa{:
oO I
I
10
àE6
11
12
13
'14
15
0.1 I.0 10 't00
APPLIED PRESSURE - ksf
Moisture Content =
Ðry Density:
Sample of: Silty Sand
From: Pit 1 at SFeet
11.1
90
percent
pcf
il
il
il
il
\
Compession
.upon
wetting il
ti
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lit \il
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1 15 136A (E¿
HEPTTI'R.II+
SWELL.CONSOLI DATION TEST RESULTS Figure 3
ç.(l)(}o)CLoÕqrtj c{Ë€IEJ .F,fiË ¡Çç[(rJiü.ï à* c.lEPiË:J oËi;e !].ËËåEEIIvoúIJ'Pña_ t'- C.=E aiÈI +s]--Fc)C?OvUJc[fUJ(ntIJEû_cfu-lJo-Ê-(3c\l(rt.fC\IeOro0o¿ uosuedr3 - uo¡ssalduoS{ÐÌ.-6o(ofarLOFCNI:fU)LLIÊcFU)TJJt--zoË0=oØzoOI-lJUJ3!í-()L=(J)iE
HEPWORTH-PAWLAK GEOTEC¡{NICAL, INC.TABLE 1SUMMARY OF LABORATORY TEST RESULTSJob No. 115 1364so¡L oRBEDROCKTYPESilty SandSlightly Silry SandSilty SandUNCONFINEDCOMPRESSIVESTRENGTHfPSF}PEROEJIITPASSINGNO.200SIEVELIQUIDLIMITPLASTICINDEX33GRÀTSAND4vùGRAVEL(v"'tNATURALDRYDENSITYlocfl909282NATURALMOISTURËCONTENTt%l11.111.915.4SÄMPLE tOC¡flOt'lDEPTHlf$364PIT12