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In 2006, the City removed the filter media in the two filters at Water Treatment Plants 3 <br /> and 3A and replaced it with a finer filter material, inspected the filter interiors for <br /> corrosion and made coating repairs as necessary, and installed a different complex <br /> chemical feed system. The work was completed and has reduced the radium levels below <br /> 5.4 picoCuries per liter for radium as required by the MDH. <br /> In 2007 at Water Treatment 4, and in 2008 at Water Treatment 5, the City installed new <br /> finer filter media while reusing the existing chemical feed system, sandblasted and <br /> painted the entire filter interior to remove the existing corrosion and installed an airwash <br /> system to assist with the backwash process. The work was completed has reduced the <br /> radium levels below 5.4 picoCuries per liter for radium as required by the MDH. <br /> Water Treatment Plant Information and History <br /> Water Treatment Plant 3A is connected to Well 11. <br /> Built: 1987 <br /> Filter: Tonka Filter <br /> Coating: Exterior re-coated in 1995 <br /> Interior spot-coated in 2006 <br /> Recommendations for future filter coatings and repairs: <br /> • 2016 - Structural repairs, interior and exterior coating [$125,000] <br /> • 2016 - Install baffles in detention side to get better chemical mixing to aid with <br /> radium removal. This work will be similar to work at WTP's 4/5. [$250,000] <br /> Water Treatment Plant 3 is connected to Well 8. Well 8 is located offsite and pumps to <br /> the Well 11 site where this filter is housed) <br /> Built: 1985 <br /> Filter: General Filter <br /> Coating: Exterior re-coated in 1995, minor touch-up on welding failures <br /> Interior re-coated in 2006 with new filter media(TonkaZorb) <br /> Recommendations for future coatings and repairs: <br /> • 2026 - Install baffles in detention side to get better chemical mixing, new media <br /> • 2026 - Recoat interior and exterior <br /> Water Treatment Plant 4 is connected to Well 10. <br /> Built: 1983 <br /> Filter: General Filter <br /> Coating: Exterior re-coated in 1995; 2007 touched up welded areas & spot failures. <br /> Interior re-coated in 2007 with new filter media <br /> Air scour system installed in 2007 <br /> Recommendations for future filter coatings and repairs: <br /> • 2027 - Interior and exterior coating, new media, under drain replacement <br /> Water Treatment Plant 5 is connected to Well 12. <br /> Built: 1987 <br /> Filter: General Filter <br /> 12 <br />