The City of Nogales, Arizona, has agreed to transfer its ownership of the International Outfall Interceptor (IOI) to the U.S. Section of the International Boundary and Water Commission (USIBWC).
]This agreement, which the City Council approved on April 10, will take effect once
USIBWC receives $12.5 M for operation and maintenance of the 9-mile pipeline through a
congressional appropriation or other funding. The ownership transfer was made possible by the Nogales Wastewater Improvement Act of 2023. The Act was led by Senators Kyrsten Sinema and Mark Kelly and Representatives Raul Grijalva and Juan Ciscomani.
The IOI carries transboundary wastewater flows from Nogales, Sonora, Mexico, and Nogales and
Rio Rico, Arizona, to the Nogales International Wastewater Treatment Plant (NIWTP). Installed between 1970 and 1971, it is comprised of reinforced and unreinforced concrete pipe that
ranges in size between 24 inches and 42 inches in diameter. Much of the pipeline lies underneath the Nogales Wash channel and Potrero Creek. The City of Nogales contracted a study to assess the condition of the pipeline in 2005 and identified significant pipeline deterioration.
Rehabilitation of the IOI is being undertaken with funding participation from the USIBWC, and
supplemental funds from the Mexican Section of the International Boundary and Water
Commission, the State of Arizona, and Freeport McMoRan Foundation.
Under two contracts awarded in 2021 and 2022, SAK Construction used Cured-in-Place-Pipe (CIPP) technology where a liner is inserted in the existing pipeline, then cured to form a solid pipeline inside the old pipeline. Because this technology doesn’t require excavation of the pipeline, construction will cause less traffic disruption. The rehabilitation is expected to be completed within the next 2 weeks.
Roughly 12 MGD of treated water from the NIWTP is an important contribution to the Santa Cruz River basin which supplies water for drinking, ranching, farming and other activities critical to the Arizona economy. The river also sustains habitat critical for migratory species.