Phoenix approves $55 million in contract amendments for 91st Avenue WWTP rehabilitation

Phoenix approves $55 million in contract amendments for 91st Avenue WWTP rehabilitationThe city council has authorized major funding increases for Hazen and Sawyer and McCarthy Building Companies to replace aging assets and integrate new technologies throughout the Plant 1A treatment train.

McCarthy Building Companies secured a $50 million amendment for CMAR construction services, bringing its total contract value to $50.75 million.

Hazen and Sawyer received a $5 million amendment for construction administration and inspection, doubling its engineering services contract to $10 million.

The rehabilitation scope includes primary and secondary sedimentation, aeration basins, reuse water systems, and process air supply.

The council also approved a $12 million sole-source contract with GEA North America for centrifuge maintenance at the 91st and 23rd Avenue plants.

The Phoenix City Council has greenlit $55 million in contract amendments to advance the rehabilitation of Plant 1A at the 91st Avenue Wastewater Treatment Plant. Approved unanimously during the council's September 9, 2026, formal meeting, the funding targets extensive asset replacement and technology integration throughout the facility's treatment train. McCarthy Building Companies, Inc. was awarded a $50 million amendment for Construction Manager at Risk (CMAR) services. The substantial increase builds upon an initial $750,000 preconstruction agreement, bringing the total contract value to $50.75 million. The scope of construction will address primary and secondary sedimentation, aeration, reuse water systems, disinfection, and process air supply and distribution systems. Concurrently, the council approved a $5 million amendment to Hazen and Sawyer, P.C.'s engineering services agreement. The firm will provide construction administration and inspection services, including on-site examination of materials, equipment, and workmanship to ensure quality control. The amendment doubles Hazen and Sawyer's total contract value to $10 million. The 91st Avenue Wastewater Treatment Plant is owned by the Sub-Regional Operating Group (SROG)—which authorized the rehabilitation project in August 2025—and is operated by the City of Phoenix. In addition to the Plant 1A rehabilitation, the council approved several other wastewater capital and maintenance contracts via its consent agenda. This included a $12 million sole-source contract with GEA North America, Inc. for OEM parts and maintenance of Westfalia centrifuges at the 91st Avenue and 23rd Avenue treatment plants, ensuring reliable separation of solids and sludge. The council also awarded a $700,000 contract to Xylem Water Solutions U.S.A., Inc. to supply membrane diffusers for the aeration basins at both facilities.