WRRF Digester and Disinfection Improvements

The proposed Work is generally described as follows: 1. Sitework a.Install a 30” pipe from the existing Grit Building to the Equalization Basins. b. Extend 36” secondary clarifier effluent pipe to new disinfection basin influent. c. Install 48” pipe between the new disinfection basin effluent and connect to outfall piping. d. Extend 12” MEC return line to new disinfection basin. e. Install 24” pipe between the existing Equalization Basins and new disinfection basin. f. Provide a second bay for septage receiving. Add new reclaim water loadout station, flow metering, and sand trap structures. g. Addition of standby generator. h. Provide roads, sidewalks, site drainage, and utilities for new facilities. i. Improve site lighting. 2. Preliminary Treatment a. Install two (2) mechanical bar screens with ¼” openings. b. Provide two screening washer/compactor systems, one for each screen. c. Replace six (6) sluice gates with new motorized actuators in the Influent Pump Station Building. 3. Disinfection a. Demolish and remove existing chlorination basin, dechlorination basin, and Mankato Energy Center (MEC) return building. b. Construct new chlorination basin and dechlorination basins. c. Construct new chemical feed building adjacent to chlorination basin. Building will house sodium bisulfite bulk storage and all sodium hypochlorite and sodium bisulfite metering pumps. MEC return and effluent analyzers will also be located in the chemical feed building. 4. Digestion Complex a. Replace existing two primary digesters and one secondary with three new anaerobic digesters b. Retrofit existing Digester No. 3 to operate as a digested sludge storage tank. c. Add Digester Control Building to include pumps, heat exchangers, rotary drum thickeners, polymer system, boilers, digester gas equipment, HVAC, and electrical equipment. d. Provide new pad mounted biogas storage. 5. Solids Processing Building a. Provide mixing pumps for the Sludge Storage Tank. b. Replace hot water boilers and HVAC equipment. c. Replace sodium hypochlorite transfer pumps and metering pumps. 6. Biosolids Storage Facility a. Construct biosolids storage facility, and make modifications to existing biosolids storage facility. 7. Operations Building a. Replace existing DAF thickening system with Rotary Drum Thickeners, which will be located in the Digester Control Building. b. Add space and renovate existing building to provide space for laboratory and facility operations. 8. Miscellaneous a. Renovations to the Sludge Transfer Pumping Station. b. Removal and addition of piping in tunnels. c. Renovations to the Water Reclamation Facility.

Sewage Treatment Plant, Renovation.

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Pollution and Waste Control Equipment, Common Work Results for Pollution and Waste Control Equipment, Air Pollution Control, Noise Pollution Control, Odor Control, Water Pollution Control Equipment, Solid Waste Control and Reuse, Waste Thermal Processing Equipment, Fluidized Bed Combustion Equipment, Rotary Kiln Incinerators, Pyrolysis Equipment, Hazardous Waste and Medical Waste Incinerators, Heat Recovery Equipment for Waste Thermal Processing, Synthesis Gas Cleanup and Handling Equipment.

Division 46 -

Water and Wastewater Equipment, Residuals Stabilization, Digester Appurtenances, Aerobic Digester Aeration Equipment.