2.0 MGD Manganese Removal Filtration Plant, Hazardville Water Company — Enfield, Connecticut

The Hazardville Water Company (HWC) Queen Street wellfield is the "work horse" of their system providing up to 4.0 mgd of high-quality water to its customers. Unfortunately, low levels of manganese (0.15 - 0.3 mg/L) periodically caused water quality concerns in their distribution system. The HWC retained LEI to design a treatment facility to eliminate the manganese staining problem.

HWC and LEI piloted several types of filtration units, varying filter media, filter loading rates, filter backwash frequencies and chemicals used as oxidants for manganese removal.

The final treatment design consisted of four 9-foot-diameter manganese greensand filters utilizing 1.0 mg/L of chlorine as the primary oxidant. These treatment vessels are housed in a 3,000-square-foot facility which includes bulk chemical storage, office and laboratory facilities and a new pump station and generator enclosure for Queen Street Well No. 4. Two backwash water lagoons are utilized for filter backwash and to settle out particulate manganese and solids prior to on-site disposal of the water to a nearby stream.