The Arizona Department of Environmental Quality (ADEQ) and local officials confirmed an intermittent sanitary sewer overflow (SSO) in a tunnel under the international border, which transports stormwater from Nogales, Sonora to Nogales, Arizona. A SSO is a release of untreated wastewater and contains raw sewage.
When flowing, the SSO originates from Nogales, Sonora and is exiting the tunnel into the Nogales Wash about one mile north of the international border. Depending on volume of flow and frequency, the SSO could reach the Santa Cruz River.
Work continues on the International Outfall Interceptor (IOI) to fix a partial breach. The breach was discovered last week near the intersection of Old Tucson Road and the Nogales Wash.
Bank stabilization and other preparatory work is proceeding on schedule.
In the meantime, Public Health officials from Santa Cruz County and the State of Arizona advise people to stay out of the Nogales Wash and Santa Cruz River. Even in the absence of untreated wastewater, storm flows are typically high in pollutants that can be harmful.
The U.S. Army Corps of Engineers Los Angeles District is seeking approval and funding to provide technical and direct flood fight assistance to Nogales, Arizona, under the Flood Control and Coastal Emergency Act.
The proposed work would fill and armor approximately 280 feet of the exposed International Outfall Interceptor (IOI) in the Nogales Wash between Calle Sonora and Old Tucson Road that eroded from monsoon rains July 23-24.
Representative from the U.S. Army Corps of Engineers are on site at this time to assist in the development of a plan to divert the flow of water in the area of the partial breach of the International Outfall Interceptor (IOI).
Site surveys are being conducted along the IOI to assess any change to the current conditions of the wash after last night’s storms.
Santa Cruz County Public Work personnel monitored the partial breach of the International Outfall Interceptor, (IOI) late yesterday and early this morning and have reported no significant change to the status of the breach.
Samples of the water from the wash have been collected and submitted for testing and results are expected later today. We are closely monitoring for potential environmental and public health impacts.
During an inspection of the International Outfall Interceptor (IOI) on July 25, the City of Nogales public works reported a partial breach of the IOI approximately 200 yards north of the intersection of Old Tucson Rd. and the Nogales Wash.
A dislodged section of cement that encases one of the manhole accesses to the IOI, partially sheared the pipe below the waterline causing discharge of untreated wastewater into the Nogales Wash.