Laserfiche WebLink
DIVI~I~N ~C~C~AMATI~N, ~NINING AND SAF~T~f <br />Department of Natural Resources <br />~ 3 ~ 3 Sherman 5t., Room ~ 15 ~ 0 t ~ R A D ~ <br />Denver, Colorado ~O~D3 U I V I S I O ~ E Phone: X303} ~b~-357 ~ECLAl4+~ATI~N <br />FAx: {3a3~ 83~-~10~ MINING <br />SAFETY <br />I~ 1 ~~~~~~L~ Bill Ritter, Jr, <br />G~vemor <br />Hafris D. Sherman <br />Executive director <br />Date: 1~ epten~ber Ronald w~ Cottony bivision Director <br />Natural Resource Trustee <br />To: Tom ~alder~bach, Lead specialist <br />• <br />dram; N~arcia L. Talvitie, P.E. <br />subject; Permit No. ~'-191~~-~~7 ~ west ilk Mire <br />T~-~~S - 'nal Preparation Pl~~t ~n~ Baal I~andlin ~~~ilitie~ <br />Adequacy Review - eotel~hnieal <br />At your request, r have reviewed the application submitted by 1Vlou~tain Caal Company for TR- <br />11$, includ1r~g the tabrlrty Analysis of the Lower Refuse Prle prepared by Barr Engrneer~ng <br />Company and dated ~ Septerriber 2~~9. <br />The eptembcr ~nalysls lncorparates rriatrial strength parameter data reported in Exhibit ~ 1 <br />of the permit applrcatron pacl~age, ~ reviewed Exhibit 51, including 'table which i <br />duplicated in the current Barr report, dry CJnit weights and cohesion values derived for <br />Colluvial Soils are variable, acrd Barr has ta~cn average values to use as inputs for the <br />SL~PEIw stability program. Because of the potential variability, it v~ould be arise to re-run <br />the analyses using a lower, more conservative cohesion value for example, 3~~ or 0 rather <br />than $S~ psf~ for Colluvial foils. Pease ~~~iex~ the assr~~np~io~s Made rea~d~~~ the <br />c~hes~on ~a~ae for o~~a~ia~ So~~s, and r-r~~~ s~ab~~ity p~o~~~n to vet~~f,~ that eo~~uv~a~ <br />so~~s with dower cahesio~ vu~~r~es wi~~ not adve~se~y affect the a~era~~ sta~i~i~y o the dower <br />~ef~se fide the add~tio~ a, f the proposed r~e~a~ra~ran ~~a~~ Faci~i~y, <br />The Exhibit S 1 Table ~ samples analysed for Coal waste v~rere obtained from temporary <br />waste piles, and were tested prior to actual construction of the Lower Refuse Pilo ~LRP~. Ivry <br />unit weights ranged from as low as 45 pcf blighter than watery to 121 pcf. Barran analysis <br />averages these values, and assumes the unit weight of coal refuse in the LRP to be ~ 1.~ pcf. <br />Abetter source of accurate data on the unit weight of coal refuse can be found in the <br />quarterly waste pile reports submitted during the construction of the LRP between 195 and <br />1 Caa1 refuse in the lower pardons of the LRP apparently ranged between and 115 <br />pcf, while unit weights in the upper pardons ranged from t ~S to 12~ pcf. ~veral~, a moist <br />unit w1ght of 11 ~ pcf may be mare representative of the coal refuse. This value is <br />office of Gffice of <br />Mined lend Reclamatiaa Denver ~ Grand Junction ~ Dttran~o Active and In2~Ctive Mines <br />