Opening of Qualifications - WWTP CSO Tank RFQ Guaranteed Savings Contract Proj No. 121-071-A - Kokosing Ind.

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RICHMOND SANITARY DISTRICT Wm. E Ross Wastewater Treatment Plant Improvements Richmond, IN M Project improved the secondaryy treatment process. The process was last expanded in the 1980s, with some of the components dating back to the original construction in the 19305. The Phase 1 improvement project updated the aeration and secondary clarifiers while adding in the operation and maintenance elements that would ensure the longevity of the system. These improvements addressed process limiting conditions, allowing the 18 mgd plant to increase peak wet weather capacity from 28 mgd to 36 mgd. Aeration Improvements: The existing aeration tanks were constructed into a hillside and used a common header system that limited operators' ability to direct flows and isolate units. The project addressed the feed independence challenge and reconfigured the aeration to create anoxic zones. All the piping and diffusers in the tanks were replaced with a mixture of coarse and fine bubble. A new splitter box was constructed with individually piped connections to the nine aeration tanks. Each pipe included an isolation gate, allowing operators to control the flow to each tank as well as to individually remove tanks from service. Sequencing for construction allowed three aeration basins to be removed at a time, requiring the remaining six to stay in operation. Secondary Clarifier Improvements: The four existing clarifiers were improved by the removal and replacement of the mechanisms. The existing clarifiers used a double -sided weir trough located off the tank wall, allowing the flow to come up on the interior and exterior sides. The new configuration moved the trough to along the tank wall with flow coming up from only the interior side. The new trough was constructed with concrete and had fiberglass reinforced plastic baffles and v-notch weirs attached to it. The work included replacement of the actuators on the gates of the existing distribution box. Sequencing for construction allowed one clarifier to be removed from service, requiring the remaining three to stay in operation. Isolation was achieved using the existing gates in the splitter box.