USIBWC Nogales wastewater treatment plant receives first major maintenance in 15 years
The Nogales, Arizona, wastewater treatment plant managed by the U.S. Section of the International Boundary and Water Commission (USIBWC) is planning its first major maintenance since 2009, a move critical to the Santa Cruz River and its natural habitat.
Effluent from the Nogales International Wastewater Treatment Plant (NIWTP) has produced a 26-mile riparian zone in the river downstream from the plant, in contrast to the river upstream, which is dry.
This zone is a habitat for endangered species and a popular recreation area. It also replenishes aquifers serving Santa Cruz and Pima County communities.
The USIBWC, realizing equipment failures at the plant could negatively impact the quality of the effluent discharged into the river, will add several safeguards focused on redundancy and rehabilitating essential plant components.
In September 2024, the agency awarded two contracts worth a total of $1,155,742 to Clean Infusion LLC, of Columbia, Missouri, to replace train diffusers, blowers, return activated sludge (RAS) pumps, and electromagnetic flow meters, all critical components that have exceeded their life cycle at the plant, many by more than double.
To continue to meet quality parameters and develop redundancy for maintenance and repair needs, the USIBWC plans to seek additional funding to add a fourth bioreactor, a fourth clarifier, and a fourth RAS pump at the plant, as well as a replacement polymer system. The total cost could be in the range of $40 million.
This new equipment was recommended by LH&J/Arcadis Joint Venture, L.L.P, which received a $2.1 million contract to develop a USIBWC-wide Enterprise Asset Management Plan. During their assessment of NIWTP, the company identified a lack of redundancy as a problem since it means tanks and equipment cannot be taken out of service for proper maintenance.
NIWTP, the only plant in the United States that treats international and domestic wastewater, routinely operates up to 20% above its design capacity of 14.7 million gallons a day. Mexico is responsible for 80 percent of the flow coming into the facility.
The plant was constructed in 1972 and last upgraded in 2009.
“Our Nogales plant is the lifeblood of the Santa Cruz River,” said Dr. Maria-Elena Giner, P.E., USIBWC commissioner, in a press release. “For 15 years, it has successfully discharged high quality water into what would otherwise be a dry riverbed. We are making the investments necessary to continue to treat wastewater while preserving a natural habitat and recreation opportunities for the community.”
“In Arizona, we understand firsthand that water is our most precious resource,” said U.S. Rep. Juan Ciscomani in a press release. “The Nogales Wastewater Treatment Facility is critical to ensuring safe and reliable drinking water to the City, helps replace aquifers serving Pima County communities, and preserves natural habitats and recreation opportunities around the Santa Cruz River. I am grateful to see the facility undergo its first major maintenance since 2009. This investment underscores the need to strengthen water infrastructure and I look forward to continuing to advocate for common-sense projects like these between Arizona and Mexico.”
“Nogales is very thankful for these improvements to the plant,” said Nogales Mayor Jorge Maldonado in a press release. “This shows the commitment that Maria-Elena Giner and IBWC have taken upon themselves when they agreed with the City of Nogales to take over responsibility of the IOI. Thanks to these improvements, we can seek opportunities for improvements and growth in the future.”
This work comes several months after the USIBWC announced the completion of the $34.2 million rehabilitation of a half-century-old, leaking wastewater pipeline known as the International Outfall Interceptor. This 9.9-mile line conveys wastewater to the plant from Nogales and Rio Rico, Ariz., and Nogales, Sonora.