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<br />~ <br />~ <br />c.c <br />c....:> <br /> <br />leachate and runoff, generally by ditc~es aro~~d the piles which concuct the <br /> <br />water to a dam area. Little is ;~own about the composition of such leachates <br /> <br />but it is likely that the level of inorganics would be lower t~an t~e levels <br /> <br />in t~e local waters, while t~e organics level could possibly be higher. <br /> <br />However, as with mi~e drainage water, the leachate composition is ~ot kno.~ at <br /> <br />this time and it will, moreover, undoubtecly depend on local conditions. It <br /> <br /> <br />is likely, as incicated in riqure 4.3, that this runoff would be used for <br /> <br />disposal pUr?oses or c~'er low quality wate~ needs and would not require any <br /> <br />special treatment. Tti3 assumption is mace here. <br /> <br />4.4 Hic~ TDS Wastewate=s <br /> <br />4.~.1 Mine Wate~ T~eatment Concen~rate <br /> <br />We assume t~a~ ~~e ~ine water is t~eated for use in the plant in the same <br /> <br />wa1 that it is treaced tor surface discharge. The exception to this i3 that <br /> <br />=oron is not =ernovec exce?t in the relatively small amount of water Nhich goes <br />co potable ana dcmestic use (see Figure 4.3). This means that ~~e cost 0: <br />treating ~~is ',,;at.~r -..;::'11 range between aJ:;cut SO.73/1000 gal (== SZ4S/acre-:t) <br />and $0.95/:000 gal {= $310/dc=e-:~), dependi~g upon t~e cont~~inar.= concen==atic~ <br />and ~e~rane ?rccess ~sed, as discussed in Sec~ion ~.2_ <br />The concen~=ate :~om the membrane system amounts to 275 gpm for an 85\ <br />reccve~j. The ~ater will have a TCS of :rcrn 5,500 to 8,000 mg/l, consist~~g <br />~es~ly of inorganic sal~s, anc is quite suitable :or a variety of dis?osal, <br />dust control a~d rni~e uses. So long as there is a ~eec fer =his wate:, ~e <br />suggest ~hat trea~~ent is not necessarJ. However, should ~he ~ate= be i~ <br />excess or plant requir~ents, then we ass~~e it would be disposed in the same <br />way as ~~e concentrate from the treatment of the excess mine drainage wate~. <br />The :eason :or t~is is that the disposal system would alreacy be designed for <br />this type of waste and, therefo:e, it would be most economical si~ply to <br />expand the capacity to accomodate the additional ~aste. The disposal cost <br />would be the same as derived in the preceding section, that is, about $1/1000 <br />gal (= S326/acre-f~) of mine water treated. <br />4.4.2 Boiler F~edwater Treatment Slowdown <br /> <br />In the modified in situ processing of ~il shale, steam lS used ;rinci?a:ly <br /> <br />in the retorting process. It is intro~uced into t~e retort to i~crease the <br /> <br />shale oil recoverj. moce:ate the retort tempe~a~~r~ and improve t~e Off-gas <br /> <br />88 <br />