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7.1 <br />7.2 <br />7.3 <br />Current and Future Treatment Needs <br />Many of Ramsey's wells are high in manganese, which has necessitated a solution to reduce the <br />levels due to its health concerns. Ramsey's water is also high in iron and hardness. Ramsey's <br />water otherwise meets all of the primary and aesthetic drinking water standards. <br />Manganese and iron can be removed with oxidation and sand filtration as discussed in the pilot <br />study in Appendix E. Hardness removal options are discussed in Section 7.5. <br />Future treatment requirements will depend upon the class of contaminant being treated. Volatile <br />chemicals can typically be removed using an aerator (i.e. gasoline constituents, trichloroethylene <br />[TCE], radon, hydrogen sulfide, etc.). Some organic chemical may be removed using granular <br />activated carbon (potential taste and odor causing contaminants). It may also be possible to add <br />chemical feed systems to remove new contaminants using sand filters (i.e. arsenic, radium). If it <br />is not possible to remove the contaminants by volatilization, carbon filtration, or sand filtration, <br />membrane filters could be necessary (i.e. reverse osmosis). It should be noted that sand <br />filtration is typically required ahead of membrane filters because iron and manganese causes <br />fouling on the membranes. <br />In addition to potential future contaminants, a water treatment plant could be designed with <br />features that would allow it to be converted to a surface water treatment plant in the future. One <br />of these features would be filter -to -waste piping and valves. Filter -to -waste piping is required for <br />surface water treatment, but is not generally used with groundwater treatment. <br />Ultimately, having a treatment facility that is flexible and can be retrofitted to meet new potential <br />requirements is very important. <br />Treatment Capacity <br />As discussed in Chapter 4, the maximum day demand ranged from 4.1 to 5.5. MGD in the last 10 <br />years. While the overall maximum day water demand has been flat in the last 10 years, the <br />maximum day demand nearly triples the average day demand. The projected 2040 maximum <br />day water demand is 10.3 MGD. <br />The recommended capacity of a water treatment plant for Ramsey is 10 MGD under normal <br />conditions with the ability to operate up to 15 MGD for shorter periods. This will allow the City to <br />comfortably treat maximum days through 2040 and possibly beyond. <br />Manganese and Iron Removal Options <br />The most common and most cost effective option for manganese and iron removal is chemical <br />oxidation followed by sand filtration. In groundwater, the manganese and iron ions are in <br />solution. When a strong oxidant is added to the water, it converts the manganese and iron to <br />filterable solids. <br />The oxidant that is added for iron oxidation is typically oxygen via aeration or chlorine. The <br />chemical oxidant that is added for manganese oxidation is typically sodium permanganate. <br />Chlorine is a less expensive chemical oxidant, but the reaction with manganese is too slow to be <br />used in a filtration process. Options for gravity and pressure filtration are presented later in this <br />chapter. <br />FEASIBILITY STUDY RAMSY 154354 <br />Page 27 <br />