HomeMy WebLinkAboutObservation of Partial Excavation 11.16.2016H-P*KUMAR
Geotechn¡c,al Enç¡ neenng I Engrneenng Geology
lv'latenals Testrrrg i Enl irr.rnrnenlal
November 18,2016
Glenwood Caverns
Attn: Stevc Beckley
51000 Two Rivers Plaza Road
Glenwood Springs, Colo¡¡do 8160l
s t-ey-q @ gle n woodcavem s.com
Subject:
Gentlemen:
SOZOCounryRoad t54
Glenwoort Sglngs, CO Bt6Ol
Phone: {920}94S7998
Fan (920)948-8454
Emal[ hpkgilenwmd0kum¡rr¡så.oom
ollice Locatons: Pa'ker, Grenwood spdngs, anrr s[valtho¡ne, cororado
Prdect No. 16-7-524
observation of Partial Excavation, proposed Mine Drop Building, Glenwood
Caverns, Nonh of Glenwood Springs, GameH County, Colorado
As rcquested, the undcrsigned rcprescntative of H-PÆ(umar observed the partial buildingexcûvatiorl at the subject site on October 13, 2016 to evaluate the ground åon¿itionr exposed forfoundation support._The findings of our observations and ¡ecommendations for the foundationdesign are presented in this rcport. The services wete performed in accordancc with ouragr€ement for professional engineering services to Glenwood Cayerns, ¿ateO October 12, 2016.
The proposed building is located jusl u,est of the parh to the lowercave entr¡¡nce on a moderatelysteep (abou¡.30qo), south facing slope at about elevation 7035 feet. The mineshaft excavationl-ocaçd in roughly th€ center-of proposed building site was in progress and reporredly about g0
feet deep at the time of our site visit. A concrete w¡ll had been constructed on the downh¡ll sideof the shaft' with the bottom of wall close to the original ground surf¡ce. The rnineshaft w¡s not
:T.teq b,ut thickly bedded to massive limestone was exposed in thc upper pott oi,r," excavarion.Mineshaft excav¿tion spoil covered p¡rt of the building'area but in r.tuiinr'ry narurat or cut Í¡re¡$¡rtheropof rock appeared to be below about I to 2 feet ıf loo*" soil. Previous laborütory testingof the limestone for_the giant swing and carousel structures gave unconfined comp*rrín" e
strcngths bctween about 7,000 to 12,000 psi in a perpendicular direction to the bedding joint ofthe sound rock like that observed at this site. Obiervation of the limestone i".iporrO -
excavations ¡t the mine drop building site indicat€d a bedding thickne.rs of at le¡st 5 feet at thetop of the'rock. ' '
Considering the rock conditions gxposedin the partial excavation and the proposed constmction,
sp-read footings placed on the undisturbed limesione at a distance of ot least S'feet from themineshaft designed for an allowable bearing pressure of 10,000 psf can r" uie¿ iãt suppon ofthe proposed building. Footings should be a minirnum width of lB inches for continuous wallsand 2 feet forcolumns- lVe should observe the footing excavations for limestone rock bearingconditions prior to forming footings. Foundations should be designed to qp* thr section closerthsn 5 feet from the minesh¡fr.
Glenwood Caverns
Novembcr 18,2016
Page 2
The recomrnendations submitted in this letter are based on our observations of the rock exposedwithin the limited excavation of the building area and the upper part of the mineshaft excavationyd ye suitable for preliminary building.founoation oesignl we have assumed the rock beneaththe sitc has equal o¡tettcr support thanìhat exposed. vir¡at¡ons in rhe bedrock condition couldincrease the risk of foundatioñ-movement. Further studt;ithe bearing.oi¿¡,iåi, should beperformed when thc building excavation has been "orpirlrJ.If you have any questions or need further assistance, please call our office.
Sincercl¡
Steven L. Pawlak, P
Rev. by: DEH
SLP/ksw
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Red House Architecturc - Bruce Barrh ( l
H.P + KUMAR
Projecl No. 16-2-524