Laserfiche WebLink
<br />as will the first two years of mining at the Nucla East mining area. Mining in years 3 <br />Chrough 5 aC Nucla East may be dons using dragii na placement of the spoil. At both mining <br />areas the ttnal contours nq of the spoil surface wSll be accomplished with dozers and <br />scrapers. <br />Basetl on the above di acussS on, the hydraulic conducts vi ti ea of the replaced spoil should <br />vary, wSth that placed using a dragii ne exhibf CS ng the highest values. Also, regardl nos <br />of the method of pl scemeni the overall horizontal hYdraulle eonduetivi ties should be higher <br />than that 1n the surrounds ng uMtaturbed porticna of the shallow aquifers. The •`K" value <br />for the spoil determi and at Spoil Nall CN-N27 is estimated to be 40 fdday which is <br />si gnifi eantly higher than any of the "N" values determi nod for the overburden and coal <br />aquffers. <br />Data presented in Tab 9, Soils, indicates that the proms ni ng soils at both mS ni nq areas <br />had nxxlerate to al ow infiltration rates (Nydrologtc Soil Croups B and C) with a higher <br />percentage exhibiting moderate infiltration rotas. The bedrock contains extensive <br />sandstone ledges and vartt cal permeaDilttt es would be largely lima tad to the degree of <br />fracturing (secondary porosity). The replaced spoil material will not have any ledgea es <br />• these units will ha thoroughly broken up by bloats ng and verb oal perinea bilfties will Oa <br />dependent on the degree o! interconnsetad porosity rather than fraeturec. The topsoil to <br />be replaced is pro3acted to have a more even ni xture of moderate to slow inf ll tration <br />characteristics Coning To some lass of soli structure). The replaced topsoil will De <br />somewhat compacted during placement, bus the_chi sei plowing and disking operati one used to <br />prepare the soil for saedt~W should greatly improve Che topsoil infiltration rates. <br />to comparing the Nuela and Nuela East n7ntng areas, the percentage of aha7a is less and <br />the percentage oT sandstone is greater in the overburden in the Nucla East area. Thus, <br />Nuela East ahoultl exhihlt elSghely higher recharge rates. in campari son to prom ntng <br />conditions, The potential infiltraCi an and recharge races oT the replaced topsoil anO <br />spoil should be Caeparable or greater than'premS ning rotas. Tha proms ne and pos~ine <br />topsoils exhS bit comparable fnfiltration tacos and •dt eking and chisel pl owing should <br />further enhance inffltr ail on. The spoil will have greater porost tS as and rna ledges, but <br />Hill exh7 bit poorer sores nq of parts cla sizes. The undiewrDed overburden has extenaS ve, <br />hard sandstone ledgea and recharge would largely be controlled by the degree of <br />7nterconnecsod fractures. The poorer sorting of partt ele of zas in the spoil should not <br />impede vortical recharge any more than ledgea and varying tlegrees of vertical Tractors ng <br />would. <br />17-28 Revised 04/11/88 <br />• <br />REVISED MARCH 2006 Attachment 2.05.6(3}2-35 <br />