Casa Grande details $104 million Phase 4 wastewater expansion to keep up with development

Casa Grande city staff and consultants with Wilson and Company on Wednesday outlined a two-part expansion of the city’s Water Reclamation Facility that city officials say is needed to keep up with industrial and residential growth and to resolve an ongoing permit-capacity mismatch.

Brian McBride, national lead for water and wastewater at Wilson and Company, said the city is already handling higher flows than its 2022 effluent permit allowed and that Phase 4 was split into a faster, lower-cost Phase 4A that is under construction and a larger Phase 4B planned to follow. "The plant was first commissioned in the 1970s" and has undergone prior upgrades, McBride said, noting Phase 3 was commissioned in 2012.

The split was driven by urgency and funding, McBride told the council. Phase 4A uses an accelerated schedule and targeted, lower-cost interventions — including converting an abandoned pretreatment basin into an equalization basin and retrofitting biological treatment with a suspended fixed‑film system — so the plant could meet updated permit conditions sooner and postpone some larger expenditures until funding is in place.

McBride said Phase 4A included upgraded headworks, a new junction box for incoming force mains, an upgraded influent pump station (to 36…