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..... (j.l QO OJ There are two principal means by which excess mine water can be disposed. One disposal ~ethod is by reinjection into an aquifer and the other by discharge to a surface stream. Although reinjection might require little Qr no trea~~ent of the wate~, it is ccncluded in Ref. 2 (Vol. 2, p. 203) that it does not appear to be an attractive method for disposing of large volumes of water :o~ a sustained period. The reasons given ~~ere are that a relatively large number of wells wo~ld be required in locations far from the mine, miles of buried pipeline would be needed to deliver the wate~, mai~tenance would be di:ficult, and lea~age of highly saline water through f:acture springs might resul~. For these reasons we shall not consider reinjection further. Discharge of mine drainage water to a surface stream will necessitate treaenent of the water. At the present time, NPCES permit limits for surface disc~arge have not bee~ defined. Recently propcsed State of Coloraco ?e~it l~~its for discharge ~nto Picear.ce Creek from the C-b oil shale tract are shown in Table 4-5. The dLscharge limits shown Ln the left col~~ of Tabl~ 4-5 ~ere obtained =xcm t~e C-b Shale Oil venture10 during ~he early phases of t~is program and were used in definir.g the water treatnent schemes an~ ~stimati~g t~eir costs for ex=ess ~i~e drainage water. The total dissolved solies level is ~et relati~ely easily, but the limits on fluoride, =cron, phenol and ammonia could re~uire relatively expensive treatment, dependi~g upon the levels ;rese~t in the mine ~ater. The discha=ge limits shown in the right col~~ of Table 4- cf the d:af~ of this report from the Colorado 5 we~e obta~ned during review ,- f 1 ...-1 Departmen t 0 Hea t.. . ~hey are the latest proposed NPDES limits and are still unde=going review. The li~its on fluoride, boron, and phe~ol have been relaxed f=om t~e earlier limits. From what is known at this ~ime of the mi~e wate= ~antity and quality, and of the discharge quality require~ents, any generalized estimates 0: treatnent costs can at best be ecucatec guesses. Great care Must, therefore, be exercised when using any of the cos~s derivec below. In 7able 4-6 we have shown assumed ranges of contaminants i~ the mine drainage water pumped to the surface_ The ranges are based on the assumption that the mine water will be principally a mix~ure or upper aqu~=er water a~d water from the upper portion of ~he lower aquifer of the Piceance Creek Basin. The ~anges a~e based on the data shown in Table 4-4 and the U.5.G.5. data of Ref. 11. The TDS, fluoride and boron levels are roughly consistent with the planning values adcpted by Occide~tal Oil (Ref. 2, Vol. 2, p. 189), althougt we have assumed a somewhat higher mean boron level based on perscnal discussior.s