Oxnard selects Carollo for $46M WRRF treatment process upgrades

Oxnard has contracted Carollo Engineers to oversee a $46 million upgrade to its Water Resource Recovery Facility, focusing on improving treatment capacity, operational efficiency, and regulatory compliance through extensive upgrades to primary clarifiers and activated sludge tanks, with construction starting in early 2026 and lasting approximately 2.5 years.

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Carollo Engineers

Jan. 13, 2026

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City of Oxnard WRRF (Photo credit: Carollo Engineers).

The City of Oxnard has selected Carollo Engineers to provide construction management and inspection services for a $46 million upgrade to primary clarifiers and activated sludge tanks at the city’s Water Resource Recovery Facility (WRRF). The project is part of Oxnard’s 2025–2029 Capital Improvement Program and is aimed at improving treatment reliability, operational efficiency, and regulatory compliance at the 31.8 mgd facility serving approximately 210,000 residents.

Improvements to the primary clarifiers include basin rehabilitation, replacement of mechanical equipment, building upgrades, and installation of a new odor control system. The activated sludge tanks will undergo seismic retrofits, complete aeration system replacement, and installation of new submersible mixers, instrumentation, and control systems.

“The success of our Advanced Meter Infrastructure Project was in large part due to the dedication and expertise of the Carollo construction management team,” said Tim Beaman, assistant public works director for the City of Oxnard Public Works Department, Water & Wastewater, in a press release. “We look forward to continuing our partnership with a $46M upgrade of Oxnard’s primary clarifiers and activated sludge tanks.”

Construction is expected to begin in the first quarter of 2026 and continue for approximately 2.5 years, with the WRRF remaining fully operational through completion in the third quarter of 2028.