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6 <br /> <br /> <br />`,,: <br />-~ MORRISON-KNUDSEN CUMf'ANY i1.4 ----~ ~ - ~ - - - ~ ~ -~ ~- ~-- <br />I S? •:;+; <br />,'~~ <br />;qr'- <br />~' _1{R <br />A geotechnical engineer visited the site on June 18, 1981, and examined',';:: <br />.., .; <br />some of the rock cores stored on site, the mine and the spoil disposal <br />site. The mine operation, as pertains to spoil disposal, was discussed at • <br />len th with Yam a Minin Com an ersonnel. The waste dum was 'ins ecte' <br />9 P 9 P Y P ~ P~ y p <br />..r~~ <br />1jFo-r si:~ns of instability and incipient;or previous s~kid~'~s. Slope estimates - <br />-;. <br />were made with ahand-held instrument. ;er <br />~FIE~D- OBSERVATIONS<' <br />r <br />~ .,; , <br />~Oocuments ~provided• indicated personnels- from a state agency had .found>t'e <br />lion cracks in the northern end of .the spoil pile. ieConversations`wi <br />Yampa Mining Company personnel revealed that was a I~emporaryJcondi.ti <br />ywhich was rectified shortly thereafter. No~igns of instabil'ity..were fou <br />in .the reclaimed area during the site inspection. <br /> <br />', •:~• .. <br />'~ <br /> <br />In the active dump area, a number of slope measurements were made. 5~1~`o,e;'s''~ •:-,• <br />on the order of 35 degrees were found to be relativelv'cnmmnn_ -•In a c~ ,, <br />for a temporary haul road, slopes on the order of 45 degrees 'were observed,. ~~, <br />~: <br />One slope, measured at about 45 degrees showed signs of very shallow, ~,` <br />incipient movement. Tension cracks several feet long, about one foot deep <br />and parallel to the slope, were observed in the desiccated surficial soils. <br />Nearby, across the road, a previously failed slope about ten feet high •~;y_: <br />exhibited a sloughed failure surface standing at about 46 degrees. ;;~~" <br />.A.: <br />.`r <br />~YINIT''WE'IGHT DETERMINAT?lON`. <br />One problem assigned as part of the scope of work of this investigation was ;;y; <br />to attempt to estimate the unit weight of the material in the spoil pile. .~..~': <br />,•.~~: <br />:.:...: <br />i*.:....,,.. <br />._,~~I, <br />Because of the great variation in particle size distributions in various' •ar~; <br />,. t•~.. <br />parts of the pile, this problem was greatly complicated. Materials varied ~~' <br />from silt and clay sizes to boulders over very short distances. Conven- <br />tional field density tests (ASTM D-1556 procedure) and variations thereof <br />of different sizes were considered. Problems with the methods considered <br />-2- <br />