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• small a:; to he unm.a.curablc. <br />In contrast, overburden materials in C-22676 east and <br />west tracts would be. removed and replaced by a trot}; <br />shovel fleet with consequent appreciable compactian. <br />Studies by Rahn (1970 show that dra~line-laid spoils <br />are as much as a hundrzd times as permeable as truclc- <br />laid sooil.s which yield on 1}• small quantities of <br />water to wells. Very probably, therefore, ground- <br />j water recharge and discharge from the mined and <br />reclaimed portions of these two tracts could be low <br />and would not be si~::ificantly different from inferred <br />1 pre-mining conditions. <br />i <br />• Although the increased volume of ground-caater dis- <br />charged to the Yampa River system as a result of <br />1 <br />mining on the proposed lease areas would be genet ally <br />j <br />j insignificant in relation to total annual runoff from <br />the watershed, water percolating through t}ie spoils <br />can be expected to increase in dissolved solids con- <br />~ centration to about 3,000 r.-.b/1 (milligrams per later). <br />Assuming an average pre-mining concentration of i50 <br />mg/1, tliz dissolved solids load contributed to the <br />Yampa River and eveneually to tl~e Colorado River as <br />a result of minin;•on the subject lease tracts could <br />be increased from about 30 tons/yr (tons per year) <br />beforu mining to as much as 550 tons/yr after <br />124 <br />.,. <br />