HomeMy WebLinkAboutSubsoil Studyff** f, ää#åiff åiffi#åi;'Tf;ä.**
I È t !l ãnn Þnv,rnnnên;ar Seionitcrç
5020 County Road 154
Glenwnod Snlinss- CO,ì I 60 I
pilOilc: (v/u, .t+)- t>öó
fax: (970) 945-8454
email : kaglenwood@kumarusa.com
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Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, antl Summit Courty, Colorado
,^.ir;';l 1 2. ?|?i
Dave Cardiff Construction, Inc.
Attn: Dave Cardiff
506 Mesa Verde
Carhonrlale Colorado Rl ffi 7
dayç{ra¡jiiffq:qûstrtirçtisn(A,sieail.çq&1
Pr"ojectÌrln ?'l -7 -) 54
Subject: Subsoil Study for Foundation Design, Proposed Residence, Lot20, Ranch at
Coulter Creek, Saddle Circle, Garfield County, Colorado
Dear Dave:
As requested, Kumar & Associates, Inc. performed a subsoil study for clesign of foundations at
thq 91¡þ!¡ît site 'fhe S1ltd¡,'r¡-,aq cnn¡lrcfld in aaq4tl2nqq..¡-,itlr nr-'r ?gÍeeme!1t fnr:lntlchnicel
engineering services to you dated March 9,2021. The data obtained and our recommendations
based on the proposed construction and subsurface conditions encountered are presented in this
report.
Proposed Consfmetion: Design plans for the resiclence have not been cleveloped. The
pflopúsed house wiii .bc iocarecr indre ar'ea üiFiis i anci ¿anciwiii iirciy .ûc oriç tu iwu siüries
over a walkout basement. Ground floor will be structural over crawlspace or slab-on-grade. Cut
ciepths are expecteci to range'oetween a'oout 4 and iû feet. Founciation ioadings for this type of
construction are assumed to be relatively lieht and typical of the proposed type of construction.
If hrrilrlilrn ¡nn¡litinnc nr fnr¡nr{qfinn .lnadings are e;-nifi1an1l¡,' .lifferenf ftnm thnee r{q91"ih4d
above, we should be notified to re-evaluate the recommendations presented in this report.
Site Contiitions: The site was vacant anci the buiiciing area siopes ciown to the south anci east at
between 10 to 20 percent grade. Below the buildins. atea, the slooes steepen to about 25 percent
fo fhe easf anrl i5 nercent dowrr fo fhe south Vesefnfion consisfs of sase hn¡sh anrl scaffererlf _ -- -a- - e
pinon trees witir atr understory oi grass atrd wee,is.
Subsurface Conditions: The subsurface conditions at the site were evaluated by excavating two
exploratory pits in the building area and two pits in the septic area at the approximate locations
shown on Figure 1. The logs of the pits are presented on Figure 2. The subsoils encountered,
-] -
whitish, ntçdiurn dense to stiff, gravolly silt and sand. Basalt rocks in a sand and silt matrix wcrc
encountereci in Pit i at a <iepih of 2 Íbet. Resuits of a graciation anaiysis performeci on a sampie
of slightly gravelly sand and silt (minus 3-inch fraction) obtained fiom the site are presented on
ı.- ii_, -¡-.ı ,-.i ı--t,-,ñ-;-ir,-.rì ırì,ì-.Þ-.! JJ..;,.,_r!
slightly moist to moist.
Foundation Recommendations: Considering the subsoil conditions encountered in the
exploratory pits and the nature of the proposed construction, we recommend spread footings
placed on the undisturbed natural soil designed for an allowable soil bearing pressure of 1,500
y;i"ítrt oupfjuii ui"iii" ¡;rwpusvii içsiiiç¡ir;u, iiiç ¡uri¡ iv,,,,i i.u uuii¡iiilrss aii'.;, uvciii¡ig aii,.i ii ,v,v
could be some post-construction foundation settlement. Footings should be a minimum width of
18 inches for continuous walls ancl2 feet for columns. Loose and disturbed soils encountered at
the iounciation bearing ievei within the excavation shouici be removeci anci the looting bearing
level extended down to the undisturbed natural soils. Exterior footings should be provided with
:.j-=.:::::- -.-:-.:' -=i-..-.-..-¡ ìi-.+::- i- --.i'- -. .-:::'--*i-^-::: j.^. - j--.-: -----..--,.--,-. T'i-.--,.---,--+ .--i{.^.---+;,-.-: -: :.---:4uwTuoLv vvvv¡ 4uvvv lllwlr uvqrrrró vrwv4ravllJ lvl trvJL l,rvrwvLru¡!. ¡ ¡qúçr¡¡ç¡ra vi ¡vvù¡¡róit øL ¡ùa-i
36 inches below the exterior grade is typically used in this area. Continuous foundation walls
should be reinforced top and bottom to span local anomalies such as by assuming an unsupported
iength of at ieast i2 ieet. Founciation waiis acting as retaining structures shouici be <iesigneci to
resist a lateral earth pressure based on an equivalent fluid unit weight of at least 50 pcf for the
::- -'i: r "
i'ioor Siabs: i ire narural on'slle sorrs, exciusive oi lopsoii, are suiiabie io suppori iighi.iy io
moderately loaded slab-on-grade construction. 'l'o reduce the efÏects of some difTèrential
movement, floor slabs should be separated from all bearing walls and columns with expansion
ioints which allow unrestrained vertical movement. Floor slab control joints should be used to
iuiiuuv uorrragL úu'; iu siuitÅo6.,,-,ovi..iiig. i'iiu t"g.ri,*,rrrviri¡ iui juiiii. ryaviiig o,,ú oi¿ri:
reinforcement should be established by the designer based on experience and the intended slab
use. A minimum 4 inch layer of free-draining gravel should be placed beneath basement level
siabs to taciiitate cirainage. This materiai shouici consist of minus 2-inch aggrcgatc with icss than
50% passing the No. 4 sieve and less than2o/o passing the No. 200 sieve.
¡!!f!!¡.r¡¡!r1¡rtrttlt,1t,t¿ıFñ/¡¡¿\u llll lllatcrrars rur suppurt or lr()()-r sraos s{rouru De gurnpaL,tgu r() at reasl iJTo oL rnäxrfiturn
smn<iarci Proctor ciensity at a moisture content near oprirllum. R.equireti fiii can consist of rhe ttn-
site soils devoid of vegetation. topsoil ancl oversizecl roc.k.
Underdrain System: Although free water was not encounterecl ciuring our exploration, it has
L^^- ^,,- ^.--^-:^-^^.i- +L^ ^-^^ +l^^+ l^^^1 ^^-^f.^,{ ^-^.,-,{-r¡nrn¡. nnø ..1^-,^l^-,{.,-:-^ +:*^- ^fvwwrr vur v^yw¡rvrrwv ru lrrv srva lrral ¡vvør ywrvrtvu ótvurrgyv4!wr vqtr uvvvrv}, uururó ururwD vl
Kumar & Associates, lnc. @ Project No, 21-7-256
-3-
heqr¡r¡ nrr"cinifafinn rìr seâqônnl rrrnnff Fr"nzen ornrrnrl rfirrino cnrino rrrnnff r-qn c*'nÍe a ncrcherl
corìdiriori. We recoiiulìenci beiow-grade consiruction" such as reiairiing wa¡is, crawispace and
basement areas, be protected from wetting and hydrostatic pressure buildup by an underdrain
system.
The drains should consist of drainpipe placed in the bottom of the wall backf,rll surrounded above
the i::.ert 1s...g1...,.ith f:e: d::i:lilg -:.rcn'rl* =:t,^:icl. The drcir shc':ld be ple::d gt =::h 1-^'...-l cf
excavation and at least 1 foot below lowest adjacent finish grade and sloped at a minimum 1olo to
a suitable gravitv outlet. Free-draining granular material used in the underdrain system should
contain less than 2o/o passing the No. 200 sieve, less than 50% passing the No. 4 sieve and have a
maximum size of 2 inches. The drain gravel backfill should be at least lYzfeet deep. An
irrr^en-,i1rl! merlþr-ane Sr,lfh ?", ?n rr,ril ÞV{' shnrrl4 be nlq¡'e.{ h4n¡alh fhe r{tl.in gr"arre'l in a ttnrrgh
shape and attacheci to the tbundation wall with mastic to prevent wetting of the bearing soiis.
Surface Drainage: The follo.¡¿ing drainage precautions should be obsen¿ed durino cnrrqrn,cfion
and maintained at all times after the residence has been completed:
1) Inundation ofthe foundation excavations and underslab areas should be avoided
r.lr-,; i r ig i.i!i,:i a.¡..'1 i.,,r,
2) Exterior backfill shouid be adjusted to near optimum moisture and compacted to
at least g5olo of the maximum stan<larcl Proctor elensity in pavement anel slab areas
and to at least 90% of the maximum standard Proctor density in landscape areas.
Free-draining wall backfill should be capped with about 2 feet of the on-site, finer
grl Je4 r,-:il l tc :¡i--;l = l:-äf;l s';;i¡l =1 li:;tl =;1.
3) The ground surface surounding the exterior of the building should be sloped to
drain away from the foundation in all directions. We recommend a minimum
slope of 12 inches in the first 10 feet in unpaved areas and a minimum slope of
3 inches in the first 10 feet in pavement and walkway arsas. A swale may be
:reed:d -phill n+ 4i:=:!:-:f::e r::cff :::=:C the:-^sidetrce.
4) Roof downspouts and drains should discharge well beyond the limits of all
backfill.
5) Landscaping which requires regular heary inigation should be located at least
5 feet from the building. Consideration should be given to the use of xeriscape to
!imit ^ntenfi¡l r¡¡ettir-rc nf enilq þc!4-¡-' the {^ttn4.ati4n ¡.3r1ç9d h.' ir¡!gqfian
Septic Field: A USDA gradation test performed on soils from 6 ta 7 feet deep in Profile Pit 2
i-li^^+^^ +L^ ^^:l +-.^^ Ç^- ^^^+i^ ¡^^:^- :^ ^-^,,^11,, S^-¡-. I ^^q .-.1"ì-h .'t ^"1ã t ^ ^.'i+^l'l^ f^- oiiiUiUAtçS üÍiv SUii LJiiU iLri JUPtiU L¡USigiI lii \jiax-vvrrJ rJCLrrLrJ rJ\r.uu wllvlt ù[\.,urLl uu ÐulLúLLrrv r\rr ¿1.
conventional septic system. The septic system should be designed by a professional engineer.
K::==: -- -^-e:+litt::. !::.6 D¡¡ia¡f N^ t,t-7.-tEA
-4-
LÍmÍtations; This study has been oonducted in accordance with gonerally accepted geotechnical
enginccring principles and practices in this aÍea at tiris time. Vie make no \¡/amanry either
express or implied. The conclusions and recommendations suburitted in this report ale based
, - - .- i!- - l-- - -3--.-- !- r ^ti.f,Ït,-riaTt¡i-rÃ,1 îf,1ûa-r Íäú Ãvñi,rñ,!ì^ñr ñrÌ.r ävıô!rnia^ ^+ ùhd ¡.a^.¡ir.rñ.r rñ/¡r,a,riô; ,-- ili^rr-¡ Ìút/U¡¡ .¡¡v süLü vü*i4¡v$ ^iv¡ii t^^v y¡\I/¡v^úivii ptaþ v.itEi satu üi iiiË ii.;üi;-;;ú iiii;iti;;;J Ui; ;;Bü¡ii I
and to the depths shown on Figure 2, the proposerJ type of construction, and our experience in
the area. Our services do not include determining the presence, prevention or possibility of mold
or other bioiogicai contaminants (lvíûBC) <ieveioping in the flrture. If the ciient is concerneci
about MOBC. then a professional in this special field of practice should be consulted. Our
¡l Þ i i a | ! ¡. t ¡ i ¡: ô.t ¡r¡3 ¡ r ¡¡Fr--iñiì!!ìi¡{ ¡!-!r-'¡¡i,-aÊ iñiFÍñíi¡-X¡iii:i ;jñii Ë-t¡râñrì¡.ãii¡_,r. ,-.i i:aÊ Çi¡i-.i'i¡.-r-:;:s i.iiñriiiiiiE+ rriÊrr..r
-__¡¡!^;^u* +, i¡¡v
exploratory pits and variations in the subsurfüce conditions may not become evident until
cxcavation is performed. If conditions encountered during construction appear different from
+!----.-.-- -l-------".:L-----l :-- +!=i- ".--,*---.¿ -=.- -l- -=-! I l- - ,- - tt.r, .' *¿ - --- ----t---^2 --^ -"crt^ -ulusË uËsçtlusu ur tluù lçl.tu[t, Wç s¡rourtl Ue rlulilrgc AI uÍice SO fG-eVAiUAIiOä Crf üie
recommendations may be made.
'iitt" rcprri i¡oo i-rccri ¡rivparcú iur iirc e¡uiu¡rut; usc iry uur viiçui iur r.iasigii purpuuçs. ìVç ð.rç itüI
responsible for technical inteqpretations by others of our information. As the project evolves, we
should provide continued consultation and field services during construction to review and
monitor the impiementation of our recommendations, an<i to veritv that the recommendations
have been appropriately interpreted. Significant design changes may require additional analysis
^---^i:¿:^^¿:^--¿^ +:-^ ..^^^-----^--:-t: -:'t----^:-^ ::7^ '.^^^-----^-; --^ -:¿- --.^--,_--^:--.,v¡ ¡rrÙi¡ri.¡a/d¿iiv¡¡ú Eù liiV ivvvr¡ur¡vr¡i¡¡¡í¡\lii;i y¡uùv¡rrvi¡ ¡iü¡üi¡¡, rr v rvvùri¡¡iiViis i/i¡ errv vuJvr V.iiivil
of excavations and foundation bearing strata and testing of structural fill by a representative of
the geotechnical engineer.
If you have any questions or if we may be of further assistance, please let us know,
Respectfu lly Submitted.
Þi -- ,-.-. ,, -- d] å ........ ^i-- ¿! .iiÈ!Ìcaû;- és rå+þ{¡ü.Ë¿è¡;Ésr
L.i ',.;;z-
Í)aniel E. Hardin
t *-1{þt
T.}._,_ ì,-.-,. cit Ê
DEHlkac
atúachments Figure I * Location of Exploratory Pits
Fisure 2 - [,oss nf ],lxnlnrafnrv Pifsç ç' - "---f-*
Figure 3 -"Lcgcnd and Notes
Figure 4 * Gradation Test Results
taifrllfra e- E lU¡ I r'- ¡ :rBâr¡trñfi ¡ aôî !¡Af !t¡f¿\¡ tÞsrv J v vut I v¡ous5¡vrr r vùt ¡wosrtu
ut/.
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SILT=27
ULAI = IU
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"í 21 -7-256 Kumar & Associates LOGS OF EXPLORATORY PITS Fig. 2
PIT 1
EL. 7446'
Ptl 2
EL. 7558'
PROFILE PIT 1
EL. 7326'
PROFILE PIT 2
EL. 7332'
I EêEÀ|N
lUrJ\.,,lL; \J1\\rAl\lt/ JAI\Ul JlLl MAI YVlln f\\.,,\,, lJ' rlñM, MtrlJl, LlAfff\ EK\JVYI\.
cLAY (CL); StLTY, SANDY, STIFF, SLIGHTLY MOIST, BROWN
BASALT ROCKS: GRAVEL TO BOULDER SIZE. IN SANDY SILT MATRIX. DENSE. SLIGHTLY MOIST
WHITISH.
i r' lSlLr AND SAND (ML-SM); GRAVELLY, MEDIUM DENSE TO STIFF, SLIGHTLY MO¡ST, WHIT|SH.VIt1
DISTURBED BULK SAMPLE
PRACTICAL AUGER REFUSAL.
NOTES
1. THE EXPLORATORY PITS WERE EXCAVATED WITH A BACKHOE ON MARCH 9,2021.
F\rñt ^n ¡ T^F\/ ñrÌê ^ ñññÂ\rrr ¡L. tnr LUUAttvttJ vf tnr L^rLvnAtvnt rttJ llr^r MLAJU^Lu ñTTÃv^tlvlHtLLt ol TAvillv rnvryl
FEATURES SHOWN ON THE SITE PLAN PROVIDED.
-1. ¡ñL -LLÏ.'ì¡i'-¡t'i+ iii iñL Lrai Lü-aiii:-ji--ì i-iii íiL-rL L-¡tii¡_iLü o¡ i¡aiLir¡UL;ìiiu¡i GL¡iiLLìì
CONTOURS ON THE SITE PLAN PROVIDED.
4. THE EXPLORATORY PIT LOCATIONS AND ELEVATIONS SHOULD BE CONSIDERED ACCURATE ONLYT^ TUr nr^Drr l\/Dt trn DV Îutr t¡trTu^n tlerñ¡U ¡-L ULU¡\LL IIVi¡ L¡LU U¡ IIIL IVILIIIVU UJLU.
5. THE LINES BETWEEN MATERIALS SHOWN ON THE EXPLORATORY PIT LOGS REPRESENT THE
AFrKUÃtMATr uüu¡¡unxrL5 6LrwLLN MATExlnl 'r rrt-s ANU triL rKAN5rruN5 MAt ËL úr(AuuAL.
6. GROUNDWATER WAS NOT ENCOUNTERED IN THE PITS AT THE TIME OF EXCAVATION. PITS WERE
trñçFrllLLÈU JUÞ.iÉqULIìÌ l\J JtlMrLllTlr'
7. LABORATORY TEST RESULTS:
WC = WATER CONTENT (%) (ASTM D 2216);
+4 = PERCENTAGE RETAINED ON NO. 4 SIEVE (ASTM D A22);
-2OO= PERCENTAGE PASSING NO. 2OO SIEVE (ASTM D 1 1 4O);
GR^.VEL = PTRCENT RET.^.IN[D 0\l NO, '!0 SIEVE:
SAND = PERCENT PASSING N0.10 SIEVE AND REïAINED ON NO.325 SIEVE;
cil T - DrD^rllT D^qellln lln 24tr cltr\rtr T^ D^DTlnl r QlTr ^nîl/I/.J¡L¡ - r Lt\vLttt I ñJrtttu ttv. g¿u JtLtL tv I ñt\ttvLL Jlal .vv¿tvtlYtt
r,,!é! - ! L!\-r_,L!!! -_r!YIF-LLL!\ !!!ts_!! l5-!\-!!r_'LL 1t!4L :r_¡r_¡4!!!!Y!:
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SIEVE ANALYSIS
:
H
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htÉ
DIAMETER OF
CLAY TO SILT
GRAVEL6XSANDl'A
LIQUID LIMII
SAMPLE OF: Sllghlly Grovelly Sond ond Silt
PLASTICITY INDEX
: i r i-tliiL,:ll..ll- l f Llil. ll Lil.- 1.1,75 9.5 t9 !6,1
SILT ANO CI ÀY 16 ?1
FROM:Plt2el-5'
COBBLES
lhe!. l€rl rslultr dpply only lo the
rqmplsr whlch wôrr lorlrd, Thrbrllng rcporl rholl nol br roproduc6d,
oxoopl ln full. wllhoul lho wrltlonqpprovol ol Kumor ll Arlgoiolr!, lno,
Sl.vc onolyrl! lesllng b portom.d ln
cccordonc. wlth.ASTU D6915, ASTM D7928,
ASTM C156 dndlor ASTY Dll¿o-
HYDROMETER ANALYSIS
CLEAR SOUARE OPENINOS
sfÍ' tf¿' t t tr' sr"" l--- ' '-
" .1'
SAND GRAVEL
FINE MEDIUM COARSE FINE COARSE
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¡21 -7 -256 Kumar & Associates GRADAÏION TEST RTSULTS Fis. 4
I r\/nn^[r-ÎTn ^Àt^t \/Ô¡c Ôtr\rr ^Àr^t\/ôro
24 HR, 7 HR
.001 .002 .005 .009 ,019
i
1 MIN,
#32s #140 #60 #3s #18 #10 #4 3/B' 3/4 1
()-7
îÃ
+1
o-
Fz.
LrJOVLI
0_
5050
O
LJz
i_
tl.jM
z
E.
LrJL
90
70
4060
3070
20
10
20
30
106 .025 .500 1,00 2,00
3' 5',6" B',
4.75 9.5 19,0 37.5 16.2 152 203
100
.045
utAtvtE I Én uT TAn I tvLEo ¡t\ rvilLLilvtE r Eno
I
I GRAVEL
v FINF I FJNF I MFntrJ[,4 I
GFAVEL 21 %SAND 42 %stLT 27 to CLAY 10 "/o
trÞ^N ¡- Dr^{il^ Ðì+ a G\ et -7t
I tt a \Y v ¡I len^ Q^ll TVDtr. iêrnrrnlh¡ Q-nrlv I ^-mrJ vqr rvJ Lvqr I I
ì
11
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