Agua Nueva Water-Reclamation Facility (ANWRF)

Challenge

The Agua Nueva Water Reclamation Facility (AGWRF), (formerly the Pima County Water Reclamation Facility) project consists of the design, construction, acceptance testing, operation and maintenance (including all capital maintenance) of a new water-reclamation facility as part of Pima County’s new Water-Reclamation Campus. Additional capital improvements included an influent pipeline from the facility to the county’s plant interconnect, an effluent pipeline from the facility to the county’s existing Santa Cruz River outfall, a primary sludge line from the facility to the county’s existing sludge transfer pipeline, a bypass sludge line from the facility to the plant interconnect, and all related capital improvements. The capacity of the new facility is 32 million gallons per day (mgd), based on annual average daily flow, with an ultimate capacity of 48 mgd.

Approach

The County chose to use DBO project delivery to secure substantial benefits for its customers, including timely, efficient and cost-effective scheduling, optimal risk allocation, competitive design selection, clear assignment of performance responsibility to a single contracting entity, long-term O&M efficiencies, cost savings beyond any that could have been expected with traditional DBB project delivery. In 2010, the County awarded the contract to CH2M, which devised an innovative treatment process that uses Dissolved Air Flotation as primary clarification and 5‐stage Bardenpho wastewater treatment enhanced with step-feed capabilities, followed by deep-tank secondary clarification, The odor-control solution, which consists of two separate systems—a centralized odor-control biofilter system and a dual-bed carbon absorption system—offers low lifecycle cost and exceptional performance.

Result

The ANWRF project began operation in 2014. Overall safety performance has been excellent, with only a single recordable incident in over 825,000 hours of operation The contract amount was $164 million—almost a third (32%) lower than the budget cap of $240 million. CH2M will operate the facility for 20 years. The site layout allows room to expand to accommodate future population growth of Pima County.