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4-6 <br />' therefore making this treatment scenario highly eusceptb]e to site-specific conditions and TDS <br />' concentration variabilities. Because the IO treatment system will be able to effectively manage <br />these variations, mine waters will be routed to a common IO treatment system consisting of <br />three IO units. The three IO units will be arranged in parallel eo that two units (primary and <br />' secondary) can be operational while the third unit is undergoing IO resin regeneration. <br />' IO is a process in which undesirable cations or anions in solution are selectively removed by <br />transfemng the Tone to a solid media which accept the ion while transferring an equivalent <br />' number of desirable ions back into the solution. The IO media has a finite capacity for storage <br />of ions; as such, the media eventually become saturated with undesirable ions which require <br />' removal. The undesirable ions are then removed from the solid media by regenerating the solid <br />media with an acid or caustic containing the desirable ions. The regenerate solutions from the <br />' cation and anion IO units will be either acidic (cation) or caustic (anion) and concentrated in <br />the undesirable species. These regenerated solutions would then be managed on site by <br />combining the two and adjusting the pH to precipitate followed by filtration for solids removal. <br />The filtrate will be routed to a sedimentation impoundment and the solid managed by off-site <br />' stabilization and disposal. Based on the data presented in Table 1, it is anticipated that the <br />volume of concentrated acid and caustic solutions necessary to regenerate the IO units would <br />be approximately 1,500 to 2,000 gallons per day of each. <br />The major work activities associated with this management alternative include the following: <br />• Construction of equalization surface impoundments. <br />• Construction of a facility to house the IO treatment system. <br />• Installation of three parallel IO units. <br />• Installation of support piping and pumping systems. <br />• Installation of regenerate treatment syretem. <br />4.4.2.2 Effectiveness <br />The technical basis and approach for this alternative have been fully documented and could <br />' be accomplished using custom fabricated equipment and the existing sedimentation impound- <br />ments. The effectiveness of IO treatment for removal of dissolved sodium and bicarbonate ions <br />is essentially 100 percent assuming that breakthrough can be effectively managed and channel- <br />ingcontrolled. This removal efficiency would correspond to a 95 percent removal efficiency Cor <br />t <br /> <br />