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4-5 <br />dissolved sodium and bicarbonate ions ie approximately 96 percent when the RO unite ere <br />operated at 80 to 90 percent of design capacity. <br />4.4.1.3 Imolementability <br />This alternative could be implemented at the facility with only minor delays for equipment <br />design and delivery. Based on the treatment system size requirements for the anticipated mine <br />discharge flow rates and TDS loadings, construction and operation of the mine water treatment <br />' system and associated equipment should not affect facility operations. <br />4.4.1.4 Costs <br />The budgetary cost to implement this alternative for the complete removal (95 percent <br />effective) of TDS i^ the mine discharges is estimated to be $7,100,000 for the two current <br />discharges and $10,800,000 for all three discharges. This cost ie based on treatment of 140 <br />gallons per minute et a daily TDS loading of 2,600 pounds for the two current discharges and <br />' 290 gallons per minute of a daily TDS loading of 5,200 pounds for all three discharges. The <br />budgetary coat to implement this alternative Cor partial removal of TDS in order to achieve <br />' compliance with the 2,000 pounds per day and 350 tons per year salinity limitations is <br />estimated to be $4,400,000 for the two current discharges and $7,300,000 for ell three <br />I discharges. This cost is based on treatment of approximately 35 gallons per minute at a daily <br />TDS loading of 590 pounds for the two current discharges and 110 gallons per minute et e <br />daily TDS loading of 3,200 pounds for all three discharges. <br />' 4.4.2 MA3 - OnSite Treatment Utilizing Demineralization Ion EScchange and Direct Discharge <br />4.4.2.1 Description of Management Alternative <br />Mine waters could be collected, equalized, and treated prior to discharge. After equalization <br />' and particulate settling, the mine waters would be filtered to remove solids which may impair <br />operation of the treatment process and then routed to the treatment system. <br />' The selected processes for the demineralization of the mine discharges would be atwo-staged <br />ion exchange (IO) treatment system. The first stage of the IO treatment system would consist <br />of cation exchange (hydrogen cycle) followed by anion exchange (weak-base cycle) to polish the <br />' water produced by the cation eachange. Lz general, the performance of this two-staged IO <br />treatment will not be dependent upon the variation in the influent concentrations and flows, <br /> <br />