HomeMy WebLinkAboutGeotechnical Investigation 06.26.19Wednesday, June 26, 2û19
11:23 AM
RË.CEIVED
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Huddleston-Berry
Engiícering & Tcsting, LLC
2789 Rivenide Parkway
Grond Junction, Colorgdo E1501
Phor¡e: 970-255-8005
In fo@huddlestonbeny.com
June 26. 2019
Pdect#O1953-0002
Mitch Teaney
162 Boulder Ridgc
Parachute, Color¿do 81635
Subject:Geotechnical Investigation
52 Hogan Circle
Parachute, Colorado
Dear Mr. Teaney,
This letter presents the results of a geoteclurical investigation conducted by Huddleston-Betry
Engineering & Testing" LLC (HBET) for 52 Hogan Circle in Parachute, Colorado. The site
location is shorvn on Figurc L The proposed construction is anticipated to consist of a single
family residence. The scope of our investigation includecl evaluating Lhe subsurface conditions
at the site to aid in developing foundation recommendations fot the proposed co¡rstruction.
Stte Condltions
At the time of the investigation, the site was open with modsrate slopes down to thc northeast.
Vegetation consisted primarily of sparse rveeds and gl'asses. The site was bordered to the north
by á vacant lot, to the south by an existing residence. and to the west and east by Hogan Cit'cle.
Subsurface Investlg¡tion
The subsurface iuvestigation inclucled tlvo test pits as sholvu on Figule 2 : Site Plan. Ïre test
pils rvere excavated to a depth 8.0 feet belorv the existing ground surf¿ce. T¡ped test pit logs are
inclucled in Appendix A.
As indic¿ted on the logs, the subsr¡rflace conditions at the site were consistent. The test pits
encountered 1.0 foot of topsoil above tan, moist medium stiffsilty clay and silt soils to the
bottoms of the excavations. Groundwater was not encountersd in the subsurface at the tims of
the investigation.
Laboratorv Tesfins
Laboratory testing was conduçtcd on samples of the native soils cncountered in the test pits. The
testing included grain size analysis, Attelberg limits determiuationo nalural moislure co¡rtent
determination. and maximurn dry density and optimum mo¡stlre content (Proctor) determination.
The laboratory testing results are included in Appendix B.
Unfiled Notes Page I
-il llogun Circle
í0 r 953-0002
06t26il9
Huddlcs!on.Beûy
{.¡ì¡*ritrßSl-'in{ltc
Laboratorv Testing
Laboratory testiug rvas conductecl on sanrples ofthe native soils enÇountered irt the test pits. The
tcsting incluclcd grain sizc analysis, Attcrbcrg limits tlctcrrni¡ration. ¡ratttral moisturc contcnt
dctcr¡rination. rvatçr solublc sullatcs contant dctcnniuation, ¿ncl maximum dry tlcnsity and
optimum rnoisfure couten[ (Proctor) clstermination. The laboratory tcsting results are included in
Apperrctix B.
Thc n¿tivc silt soils rvclc indicatcd to be slightly plastic. ln gcneral, basccl upon our cxpcricncc
rvith similar soils in the vicinity olthe subject site, the native soils are anticipated to bc slightly
collapsible.
Foundation Recommendations
Bascct upon the rssults of thc subsurf'acc invcstigation and naturc ol thc proposccl construction.
shallorv fou¡{ations are recornmeuded. Spread footings aud monolithic (tumdorvn) sttuctulai
;labs arc both appropriatc loundation alternativcs. Horvcvcr. as discussccl previously. thc n¿tivc
soils arc anticipatcd to bc slighlly collapsible. Thcrcforc, in order to limit thc potcntial lor
cxçessive clillelential mo\,elnents. il is recommcncled thal the founclations be cottstructed above a
m' rimum ol24-inches ol structural hll.
Tlrc nativc clay and silt soils. cxclusivc of topsoil, alc stlitablc fbr rer¡se as structural fiìl.
lrriportccl stluctural till should consisl ofa grauular, uou-expansive, non-free drainìng rrratsrial
such as %-inch nrinus crusher fines oI CDOT Class 6 basc course. Unless it can bc cletrroustratccl
tlrat the matcrials ars not fì'cc-clraining, pit-run tnatcri¿ls should not bc ussd as slructural fill.
For spread footíng lor.¡ndations, the footìng areas rìray be trenched. Horvevet', fol nronolithic slab
fot¡ndatio¡s, the struclur'¿l {ìll should exteutl act'oss thc entire building pacl area to a clepth o1'24-
i¡chcs bclorv thc turndorvn edges. Structural fill shoultl cxtcnd latcrally beyoncl thc cdgcs ol thc
lì¡unclations a distancc eqr.ral to thc thickncss olstructural fill for both lìrurrdation typcs.
Prior lo placement of stnrctural ñll, it is lccomllrcnded that thc bottom of thc fountlatio¡r
excavation be scari{ìed to a deplh of 6 to 9 inchcs. moisture conclitioned, attd compacted to a
rnininruur of 95% of the standard Proctor maximum dly densily, rvithin + 2% ol the optinlunl
nroistnlc contcnt as dctqrninccl in accordancc rvith ASTM D698. Stlrrcttrt'al fill shoulcl bc
moislutc conditionccl. placcd in maxirnr¡nt 8-inch loose lifts, ancl compactcd to a tninitrruttr ol
95D1, of the standard Proctol nlaximum dry density lor fine grained soils ¿nd modifìeci Pt'octor
maximum dry density for coarsç glained soils, rvithin * 2% of the optimunr moisturs contgnt as
dctcrmincil in accordancs rvith ASTM D698 and D1557, rcspcclivùly'
Stlt¡ctulal lill shoulcl be placed to rvithin 0. l-foot of the bottom of li¡undatio¡r elevation. Clean
gravel ìn cxccss of 0.1-foot in thickness belorv for.rndations rvill not be acceptablc
For structnral lÌll consisting of thc nativc soils ol impor'(cd gratrular rnatclials ancl lbundation
truilding pact preparatioll ¿s r'cçommondecl, a rnaximum allorvablc bearing capacity ol t.500 psf
nTay be usccl. Iu aclilition. a motlulus olsubgraclc t'eaction o{ 150 pci rnay bc uscrl {br stntctural
fill consisting of thc nativc soils and a moclulus of 250 pci tnay bc tiscd lor structu'al fill
consisling ol crushcr furcs or basc coursc. Fotrnd¿rtious subjcet to frost shoulcl bc at l.çast 24-
inchcs bclorv lhc lìnishcd glaclc.
flífÌn nl,rojrct Fih$:l)|g ùls5j-m02 5l l{o¡rn Ci¡cle\]ffi -.jco 0l9r3-ru1: I tollllg doc 2
Unfiled Notes Page 2
52 Ilogun Cùclc
#01953-00f.)2
t6t26/19 @**t*,***
Any steurrvalls or letaiuiug r.valls shoulcl be designed to resist lateral earth pressules. For backlìll
consisting of thc native soils or impoúed granular. uou-lrcc draining, non-cxpansivc material. rvc
¡cçonrmcnd that thc rvalls be elcsigned fbr an ¿ctivc cquivalcnt fluicl unit rvcight ol45 pcf in
areas rvhere no surchalge loacls ale prosent, All at-rest cquivalent lluicl unit rvoight ol65 pclmay
be usecl for braced rvalls. Latcral ealth prcssures should bs incl'eased as necessary to t'cllect any
sulclrargc loacling bchind tlte rvalls,
V/atel sohrble sullates are cotnmoll to the soils in Western Coloraclo. Thcre fot'e, at a tninimum.
Type I-II sulfàte resistallt cement is recotruneuded lor constluction at this sitc.
Non-structural Floor Slab and Exterior Flatwork Beçommendations
ln orclcr to rcclucc thc potential for cxccssivc diff'creutial movemcnts, it is rcconrmcndccl that
non-stnrctural fioating floor slabs be constructcd abovs a minirnutn ol'l8-i¡rchcs oistnrctulal fill
lvith subgracle prcparation, struclrral fill materials, antl filt placement be in accordance rvith the
Foundution Reconunendatiors scclion of this rcport. It is recommonclccl thaf cxtcrior flattvork bc
coustruclecl abo',,e ¿ urinimutn ol l2-inches of structural lì11.
Drainaqe Recommendations
Gratlins and dfaìilage øre cúlical .for the long-term perfornance of the stnrcture ancl gracling
arouncl tho stnrcturc should bc clcsigncd to carry plccipitation and runoff arvay fi'otn thc
struçturc. It is rccornrnenclccl that thc linishcd grountl surfacc drop at lcast trvclvc inchcs rvithin
the lìrst ten lbet arvay û'our tlìo slructure. lt is also t'ecotunçncletl that landscaping rvithin live
leet ofthe structurc include prinrarily desert plants rvith lorv rvatcr rcquiretncuts. Iu addition, it
is r'çconrmcndcd that autonl.ltiç irrigation (including drip lincs) rvithin tcn lcct of loundations bc
minimizcrl.
HBET recommends that ilorvnspout extensious be used rvhich discharge a minimuur olten fèet
{ì'om thc structulc or bcyoncl the backfill zonc, lvhichcr,çr' is greatsr. Horvcvçr, il subsurfàcc
dorvnspout clrains arc Lrtilizcd, thcy shoulcl bc carcfully constructccl of solid-lvall PVC ancl shoulcl
daylight a minimum of filìeen leet lrom the structute. In adclition. an imperrreable membrane is
recomnrcnclccl belorv subsurface dolvnspout drain lines. Dly rvells should nof be uscd.
In orcler to linrit the potential lor surlacc rnoistr.¡rç to impact the stluclure, a pcrinreter fourldalion
clrain is rcconuncndcd. ln gcnual, the pclimetcr fountlation chain should consist of prcfabricatcd
tirain tnatclials ol a pcr'(bratccl pipc ancl gravcl systctn rvith thc florvlinc of thc drain al the
trotlorr of lhe foundation (at the highest point), Thc perimetcl drain sltould slope at a lrinintt¡m
of l,At/, to claylight orto a surrrp rvith pump, An iurpermeable neurbranc is also recolrlrrenelecl at
thc basc of thc ilrain to linrit thc potcntial fur moisturc to infiltlatc into thc subsurfacc bclotv thc
loundations.
General Notes
The recomlnenclations included above are based uporr the results o{ thc subsurface illv$stigatiotl
and on our local experience. These conclusious aucl recontmenclations are valid only lbr the
proposcd çonstruction.
Cilttrìg nProjc(! filrsì1019 0l9-<340; -<: Ìfo8^n CLrlc!:tr'idJM3'mol tRk'2ú19.ilo!3
Unfiled Notes Page 3
52 Hogun Circlc
#0t9s3-0002
06t26n9
As discussed previously, the subsurface conditions encountered in the test pits were lhirly
consistent. However, the precise naturc and exte¡rt of subsurface variability may not become
eviclent until constnrction. The recommendations contained herein are designed to reduce the
risk anrl magnilude of movements and it is extremely critical lhat ALL of the recommendalions
herein be applied to the design ancl constntctiott. However, HBET canno
elßnses ìn subsurface moisture condìtìons øfld/or the orecìse nqsnìtude or extent of afiv
volume-chatlge in the nati-pe soíls lYhere sisnífrcøut íncreases ìn sabsurface moÍslare occur
due to ooor srødins. imnrooer storntwøter ntanøsement, utílìtv líne failure. exeess irripatiott.
ar other cause. during or after constractiott. síenÍÍîcaat movemenls are oossìble.
In addition, the success of the structure foundations, slabs, etc. is critically dependent upon
ptoper construction. Thelefbre, HBET should be letainecl to provide materials testing. special
inspections. and engineering oversight durîng ALL phases of the construction to ensure
çonformançe with thc recommeudations herein. In addition, thc homeorvner should bc provided
a çopy of this report and informed of the dsks associated with living in an area of moisture
sensitive soils.
'We are pleased to be of service to youlproject. Please co¡rtact us if you have any questions or
comments regarding the contents of this report.
Respectñrlly Submitted:
Huddleston-Berry Engineering and Testing' LLC
Michael A. Ben'¡ P.E.
Vice Presidcnt of Engineering
( ilfBET\Prcjd fil*s\?o1q01951ff2 5¡ Hogîô Cirßlc\lm . a;.o\oJ 853-m0¡ LR0('2ú19 dôi 4
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Unfiled Notes Page 4
FIGURES
Unfiled Notes Page 5
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:\PPENDIX A
Tvpetl Test Pit Logs
Unfìled Notes Page 8
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APPENDIX B
Laboratory Testing Results
Unfiled Notes Page I I
/ñ\ Hutltllcston-Burry Enginccring
6Iß"Ð;iþi'";ftîFti"åi!B'
\ø e7G2ss-t'Brt
&Tcsling, LI.C GRAIN SIZE DISTRIBUTION
CLIENT Mitch Teanev PROJECT NAME 52 Hoqan C¡rde
PRO.'ECT NUMBER 01953.0002 PROJECTLOCATION BatdementMesa
U.S. SIËVE OPENING IN INCHES I U.S. SIÉVÉ NUMBERS HYDRôMETER
Ì-I
ú3
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uJ
=u
F-
Uoú
_ulÉ
100
oÂ
90
85
BO
75
70
65
60
50
45
40
35
30
25
20
15
10
0
100 0.1 0.01 0.001
GRAIN SIZÉ IN MILLIMETERS
COBBLES
GRAVEL SAND SILT OR CLAY
coarse fine coârse medium fine
f'!
lr
Specimen ldentification Classification LL PL PI Cc Cu
I TP-1, GB1 6/19 srLT(ML)26 22 4
Specimen ldentifìcation D100 D60 D30 D10 %Gravel %Sand %sitr %e|ay
a TP-í, GBl 6/19 2 0.0 9.4 90.6
ñN
:
Fzo
H
z
&
L'
Unfiled Notes Page 12
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Hud<lleston-Brrry Enginærhrg & Tsting, LLC
640 \Vhits AYsüs Unit B
Gran<l Junction, CO 81501
97G255-8005
97G.255-68 r 8
ATTERBERG LIMITS' RESULTS
CUENT Mitch Taanêy PROJËCT NAIIIE 52 Hman Clrde
PRO'ECTNUMBER 01953-OOO2 PRAIECT LOCATION Bâtdem€ntMffi
@ @
P
L
A
Sf
I
c
I
T
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N
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E
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20
LIOUID LIMIT
Specimen ldentification LL PL PI #200 ClassÌfication
I TP-l, cB1 6l4nÛt9 26 22 4 91 srLr(ML)
Unfiled Notes Page 13
Huddlcston-Berry Enginæring & Testing, LLC
6.10 Whitc ¡þsruq, Unit B MOISTURE.DENSITY RELATIONSHI P
Junrlion, CO 81501
97&.255-8005
97G255-ó8 I I
CLIENT M¡tchTeaney PROJECT NAÍtlIE 52 Hman Cirde
PRo.TECT NUMBER 01953-0002 PROJECTLOCATION BatdementMesâ
Sample Date:
Sample No.:
Source of Material:
Description of Mater¡al:
61412019
GB1
145 TP.1
slLT(ML)
Test Melhod:ASTM D698A
1
135 TEST RESULTS
Maximum ÐryDensity 109'5 PCF
Optimum Water Content . 15,5-%
't30
125
GRAIIATION RESULTS (ó/" PASSING)
#200 M 314"
91 100 100
oo;tsız
UJ¿]
ú.a
1 20
ATTERBERG LIMITS
LL PL PI
26224
115 Curves of 100% Saturation
for Specific Gravity Equal to:
2.80
110 2.70
2.60
105
100
95
90
0 5 1 25 30
WATER CONTENT
Unfiled Notes Page 14