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,_ .. / . ~ i/. i ('.. S'n'E O~-CO_~G_0... e:-_-_: •r :'a G:. <..p. it L f. I: 1. t C~~ # D_-`PARTAIE KT OF N~4TURAL RESOURCES ) . ` ' , Y`,. F ,. ~• a •' ~: • D. Monte Fascoe. E,ec~:eve Dire:tor ` (` , . Y y '~`~ •:=_~ \i~ED LA.~D RECL~\1:~TIOY- ~~ lam'/ r •, '1•"`""'•K~ •~~' tom' <23 Centennial Bu~ldin 1313 Sherman Street s' '•,. ...3 5• ~I ~ r'~y~~ ~ r ~ ~ -r ~ Denver, Colorado 80203 Te1.1303) 656-3567 ~`~ .-- David C. Shelton Director January 14, 1982 TO: Alike Savage ~`, FROiS: Jim Pendleton ~' R5: Overburde. ~•'-__ sac*_or at the Trapper t~:ine L'=ah International's sta°° has presented a calculation of overburden s::e11 based upon surveyed pit volume divided by the nunber of dragline s:+ings (buckets), tsst•-_ng co=sect deterr.=nation of excavated pit volumes and the nu.:.ber of buckets reeuired to excac•ate the pit, t;e operator should be correct :~ determining the averaoe in-place (bait: cubic yardaoe) voluc:e o` tJ:e overburden excavated per buc:;et. The operator then suggests t5at in-place excavated volume per bucket d_:•i9ed into the rated thirty cubic yard capacity of the dragline bucket should represent the average overburden sn•ell factor. This supposition would be acceptable if the aoplicant's assumption that the averaoe bucket contains thirty lEBsC.cubic yards of overburden was verified, and if the applicant included consideration of consolidation of bacl:filled spoil. The excavating capability of a dragline varies with the type of material being excavated and the Geometry of the pit. Lariations in material type imply variation in .`racmented partical size.oc•erbvrden density and resistance to bucket penetration, resulting in variations in the decree of fullness of the bucket. variations in pit oeometry affect the angle bet:.•een the cuttino plane of the bucket and the cable applying th e cutting force. The greater the angle between the a?plied cutting force and the actual plane o_` cutting, the less the a.plied cuttine force. The less the applied cuttinc force, the less efficient t'le dragline trill be, possib;u result_'nc in an incompletely filled bucket. i7tah internati'oval's contention appears to be that the goo-<_try of their oils are such teat all 0_` th.se factors balance one another and in the long run the averaoe volume of overburden contained wit.'.'^.i r. each bucl:et ecuals the "rated struck. bucket capacity" of 30 loose cubic yards. In an e_`fort to ascertain the validity of ;his assumption, I have contacted several manufactu-ors of d_*ag_ines and dragline 3uckets, and discussed wit.`: eaci the topic of bu^~:et retinas and ercae•ational ef- ficiency. Contact was made t.•ith technical representatives for A'arior., Inc., Faoe Engineering Company, Inc., and £SCO Corporation. Alarion, In.:, is a major producer of draclines. Pace and ESCO produce buckets for use on draglines. Ea c!: cor..panu's r..ethod for determining "rated struck bucket capacity" e.'as identical, conforr ne with accepted industry standards. F,1 _' three tec:.nicians concurred in the opinion that "rated struck :~uc.':et capacity" was not a valid constant for deternininc ovez- burc'cn s:: ell factors.