HomeMy WebLinkAboutUNPLATTED FORD PARK AMPHITHEATER SOIL & FOUNDATION REPORT 1980chen and
CONSULT
assoctates. lnc.
ING ENC] I. ::
SOIL & FOUiIDATION
ENGINEERING
SUITE C_7 VILLAGE PLAZA o GLENWOODSPRINGS, COLORADO 31601 o 303/945-7458
SOIL AbID IUJNDAIICI\I D{VESTIGATICT.I
PROPGED FOFD PARK A4PHTTHEAIER
\a,rl,, coroRAm
PrqareC Fcn:
RuoffZt{srtr,oorth AIA
P.O. Box 2178Vail, Colorado 81657
Septerbr 30, 1980Jcb No. 2I,0Sz
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TABI,E CF. CCNIH\TIS
PRCPGED OiSTFIJCTICN
SIIE CCNDITICD{S
SJBSOIL @{DIIICNS
IUJNDA:TICN RroVMENDATICNS
@dJND FIOORS AND FDGD SEATING
GRCTJND IGtrER OCNDITIO{S
SJFI'ACE DRAII{Affi
MiSCH.;I,ENEUJS
FIG. 1 - IffATICT! CF EEI.oRAI'ORr HOLES
FIG. 2 - IG CF E(PIORAI'ORr HOI',ES AND I,ffiND A}.ID Nc'IEs
FIG. 3 - SITELL.CO{SOTIDAIICN IESI RESTILTS
FIG. 4 AI{D 5 - CADFITICN 1EST RESIILTS
SETE I - g]!MAFY CF' IABORAIORT TEST RESUTSS
CCIICIIJSIChiS
The pncposed tleater can be for:nded wittr spreadfootings placed on the q)per natural soilgdesigred for a macim-m bearinq pressr-re of
4000 psf witJl design details ind precautions
as discr:ssed belsw.
S@PE
Thr:is rreport Plssents the results of a soil and foundation investigaticn
for tlre prcposed arphitteater to be located at Ford park, Vail, Colorado.
Thre reporE. presents ttre reccnmended epe fowrdaliql and alrorrabre
bearing pressure. general subsoil crcnditisrs togiether with ottrer soil-
related design and ccnstructicn detai_ls.
PROPCsED CCT{SrFIJCTICN
the prcposed facilitry will ccnsist of an cpen arphitheater tlpe
structure havirrg a cast-in-place and precast for.rrdation sr-pporting
a steel franre sr4rer structure. Fourrdati.cn loadings had not been
dete::ojned at tfre tine of tl.:i.s report r"rriting and are assr.cd to rarge
to an appro.imate mardrm-rn of 8 kips per lirreal foot. rixed seating will
extend tp tte slq>e fron the orchestra pit and utilize casL-in-plaoe
ccnstn:cticrr. Aborc the fixed seating the srcpe will be graded for
J-andsc4ing and seat5ng. The stage froor witr hare a finish revel
at elevaticn of 79 feet. Ttre baseirent level wilr be slaFcrarade
at an appro:cirmte elevation G7 feet.
SITE trNDITICNS
fhe site is located on a gentry slcping bench betl^rcen Gore Geek cn
the louer soutt,east side and tlre eristing Ford park fields tc tle north.
vlithdrr t]re trrilding area, tte gro-rd sr:rfar,-e slcpes cn ar aFproxinate
-2*
5t grade and st€epens to about 20c within tle fixed seau-ng and rpper
lardscaping. Elevation differential is about 15 feet. vegetatirie
csver ccn"rsj.sts mainly of sod at tlre prcposed facilitl' w:ith seve:al
tlees sunrounding t}e site.
SJBSOIL CCNDITICNS
The subsoil conditiqrs r.rer.e inr.restigated by driUinq 5 o<plonatory
holes at the 4prcocirnate locatlons shovn cn Fig. l. Graphic logs of
tie subsoil profiles encor:ntered at the test borings are shcrm on
Fig. 2. In general, tie subsoils consist of 4lproxirnately l_l to 17
feet of silty oarse granular soils to boulder size, orrerlyilg stratified
sand, gravier and obble rnixed soirs to the naxjmun rrepth Srnrestigated., 34
feet. At lest licle 5, located cn t}e landscaped bank, a granular tlpe filr
material was encountered. Results of in-prae penetration resistance
tests, presented cn Fig. 2, irtdicate the granular deposits are sed.iun
dense to dense. A consolidation test perfo:ored an a very silty sarrd
laye encountercd within the near surfae'soj_ls shcn"ed ncderace
crorpressibility rden loaded and r^etted. Gradation analysj.s perforned
cn sna11 dianeter drive sanples obtained frccn tlle test brings are
slsvcr on Figs. 4 and 5.
I"Ioi_stuxe ccntsrt of thre r4>per soils was dessri_bed as being nearly
dry to slightly moist. ecrund water was encor:ntered in the deeper bcrings,
Itrores 1 and 3, at 4procjrnate d@ti, 16 feet. Ttris rcter depth corr"eqcnds
to el-evation 52 to 64 feet *rich is approcirnately I0 feet above
Gore Creek level. l{e undesstand flood leve} for Gore Creek is approxirnately
66 feet.
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FCTJNDATIO{ RECCI44NDATICNS
The subsoils near prcposed foundation bearing leve1 csrsist
predon-inarrtry of coarse grained soils witie occasicnal firre silt
and sand rayers. considering the subsoil ccnditicns and prqosed
tl4le ccnstrucCicn, v"e reccnmend tlre use of spread fmtilgs placed
qt the rpper natural soils for sr4port of the stnrcture. The
follo,ring design and ccnst:ucLicae details should be obsenred:
(1) Footings should be plac.ed cn the r4per natural soils belot
all tqsoils or existing fiu naterial and designed fon a nracimln
bearing pressure of 4000 psf. under this plessure and assured loading
ccu'rditicns, \de estinete settlq€nts bet\^reen approximately ! to
3/4 rrrd-L rihich should essentially occur during ccnstnrc-uicn.
(2) Minirun foting width slrould be taken as 16 inctes for walls and
2 feet for colurns.
(3) ccntinucr:s for.rxlaticn walls shourd be :einfcred te and bottcrn
to spel an ursr4ported length of at least 10 feet. Bassnslt
wal-1s act5ng as retaining structures" stror:ld also be designed to
resj-st an eqrrirralent lateral ead.h pressrlre of 40 psf per fcot
nf rf cn'rf 1r fith i .\./! !.s!, utr rri-r-s pfsssrrr€ assunes a ue11 ccnpacted granular bacidiu
havilg a swface grade slcped ar,ey fron the strJcEure.
(4) All t4soi1, o<ist.irrg filt ard any lenses of fine silts and
sands fiourd at tbe base of ttre footing e<ca.vaticn should be rqrprred
and the foLings erEenited to the 1q,,rer dense soils. Boulders
encountered at ttle base of the excavaticn stror:Ld be carefully -rsrcved
to nirtimize distr:rbance.-
(5) S{terior footings should be plaed belqs frost d+th.
-4-
RCI.]ND FIooRS A{D PDGD SEATING
The natural granular soils other than tqsoil are suitable to srryport
slatson-grade onstructicrr. In the seating area, tle e<posed surface
shoul-d be cl-eared of all vegetatior, tcpsoil and any ocisting fill. In
areas slcping g:eater ttran 5:1 (horizontal to r.rertical) tte grror:nd
surface shourd be benched to prorride a revel surface for filt plaenent.
The oposed subgrade ttrrorghout tlre entire seating area should be
scarified at least 5 inches, ncistened and corpacted to at least 9Og
of standard Proctor density (AS'IM D69B). nequirea fill should ccrrsist
of non-erq>ansirze granular soils ccnpacted to at least 95t of standarrd
Proctor derrsiQz at a nrcistr:re ccntent near cpLimun. Gr-site grranular
soils should be suitable for reuse as fill nraterial prorided all
otrersize rock is rsrprred prion to placernstt.
To redue tte effects of scre diffecential rnJv€rent, builcling
i;]abs should be separated frcnr bearing rrErnbers wittr a posilive erpansicn
joint and adequately reinforced. A 4 inch free draining grarrcl layer should
also be prowided irnrediately beneatlr building slab floons. A g::avet layer
is not needed beneath the fixed seati-ng but a tJlin layer of collcacted
road base tlpe material could be used to facilite.te c€ncete placsrent.
GRSJ}{D lEftER CCNDIIICNS
Ground r,later ler,rel was encq:rrtelad at q4lrorirnate dqth 16 feet il
Test Holes 1 and 3. rtris ccrespcnds to ryprc*drnate eleratiqr 62 to
to 64 feet. Gare eeek appears to be at 4prroximate eleration 55 feet
with a high water leve1 at approcinate elerraticn 66 feet.
Lcnrler 1errel of the structure near elerraticn d9 feet is both abcnre
existing grotrrd vrater lerrel and hiqh \dater of tlre creek. Hcnever,
sjlce existing free water level is above Gore creek, it is possible that
this lerzel could rise at Line of peak nnoff . therefore, tfre lcmer
-5-
level of tle structure should be protected. against wetting fu an
t,.derdrain systsn. The 'nderdrain shourd consist of a perforated pipe
installed in a gravel filled trsrch praed. at. least 2 feet belo,tr finished
floor leve1 and slcped at a minirmm rE grade to suitable gravitl,
c'tflow. A Lateral drain sFrould also be provided aqrGs t}te enter of
tlte stnrqtr:r:e to shorten ttre flovr path. The gravel beneath t}e froor slab
shouLd ccnnect into tie underrlrain wstem.
S]FF'AM DRAII{AGE
The follq.ring drainage precautiurs shourd be observed during
constructicn and nraintained at arl tines after the buildirro has been
ccrpleted:
(1) Inr.ndaticn of tlre foundaticst excavaticn should be avoirted durilq
ccnstrusticrr..
(2) t4iscellaneous bad<fill arourd the buildirrg should be moistened and
ccnpacted to at least 90t stardard proclor density.
(3) The grorxrd surface surrounding the exterlor of ttre buildinq stloul_c
be slcped to drain ar,qg frcrn tte building jn alI djrections.
(1) noof dcnmspcuts arrd drains should disctrarge ve11 beyond the rirnits
of all backfill.
lIISCELIANECI.JS
Trlis report has been prepared in accordance w-itrr general-ly arcepted
soil and forsrdati-cn enqineerirg pracLices in this area for the use tY
tl:e clierrt for design pur?oses. fhe cqrclusicns and. reccnnendatiqrs
$brdtted in this reptrt are based r.pcn tte data obtained frqn the test
boni''gs drilled at the rocations indicated cn the test boring plan. rt€
-6-
nature and extent of rariaticns betrrrql ttre test borings may not beccrne
e\rident r:ntil excarratiqr is perfcned. rf , during ccnstnrqticn, soil
and grou"rd water ccnditicns apFear to be different frcrn thcse described
herein, this offie strould be adrdsed at drce so tlr,at reevaluaticn of
ttre reornendaticns nray be made. I{e recqnnend orFsite
of e:<carraticn and fordaticn bearing strata by a soil engineer.
CIIEN AND ASSOC]ajIES, INC.
By-
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