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Nogales International Wastewater Treatment Plant Rehabilitation Project, Arizona

Population Served

350,000 (Mexico); 22,000 (US)

Annual Inflow





Final Capacity


New Secondary Treatment System

Modified Ludzack-Ettinger

Effluent Criteria

BOD5 (average)

20mg/l (monthly); 30mg/l (weekly)

TSS (average)

20mg/l (monthly); 30mg/l (weekly)

Filtered Effluent Turbidity

10 NTU (24-hour average)

Total Nitrogen

10 mg/l (5 month rolling geometric mean)

Faecal Coliform

2.2 CFU (seven sample median); 23 CFU, (single sample maximum)

Residual Chlorine

5ug/l (monthly); 11ug/l (daily)

Total Project Cost


Clean Water Act Violations law suit filed

March 2000

Court-Ratified Agreement


Initial Compliance Deadline

January 2004

Evaluation of Alternatives Completed

September 2005

Grant Agreement Signed

December 2005

Construction Management Tender Closed

March 2006

Construction Management Contract Awarded

September 2006


June 2009

Plant Co-Owners / Operators

City of Nogales and the International Boundary and Water Commission

Technology Evaluation

Camp Dresser and McKee

Design Review / Construction management

Atkins and Faithful & Gould


North American Development Bank Grant and the US Environmental Protection Agency (EPA)

Working Group Members

US International Boundary Water Commission and Arizona Department of Environmental Quality, the EPA, the Border Environment Cooperation Commission, the University of Arizona, the North American Develo

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