The 91st Avenue Wastewater Treatment Plant (WWTP) is located on a 560-acre site just east of 91st Avenue, south of Broadway Road and north of Southern Avenue. The plant is owned by the Sub-Regional Operating Group (SROG) and operated by the City of Phoenix. The facility has the capacity to treat 230 million gallons per day (MGD). Portions of the facility were built in the early 1960’s, and the facility has been expanded and modified since. The facility treats the wastewater with various processes consisting of: • Screening • Grit removal • Primary sedimentation • Activated sludge with nitrification-denitrification • Secondary Sedimentation • Disinfection by chlorine • Dechlorination (sodium bisulfite) Both primary and secondary solids are thickened using centrifuges in the Solids Thickening Facility prior to digestion in sixteen anaerobic digesters using multi-phase digestion. Solids are fed to an acid-phase digester then to multiple methane phase digesters. Digested sludge is dewatered using centrifuges in the Solids Handling Facility and then hauled off-site for land application. This project will include the rehabilitation or replacement of assets throughout the Plant 1A treatment train, and may include, but are not limited to: • Primary Sedimentation o Control Gates o Basins o Clarifier equipment o Pumps, valves, and controls o Piping o Instrumentation • Aeration o Basins o Blowers o Aeration piping, valves and controls o Aeration domes o IMLR pumps and controls o Instrumentation • Secondary Sedimentation o Control Gates o Basins o Clarifier equipment o Pumps, valves, and controls o Piping o Instrumentation In addition to the above items, other assets within the Plant 1A treatment train include other pumps, motors, piping, valves, control instruments, control panels, and electrical equipment including panels, variable frequency drives, transformers, motor control centers, and process control equipment such as programmable logic controllers (PLCs) necessary for the operation of Plant 1A. It is anticipated the design and construction necessary to complete the project scope will occur over multiple fiscal years with multiple design, construction, equipment procurement and equipment installation packages being required.
