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Bisbee, Arizona, USA

Wastewater System Improvements

Status: Completed Construction

Background

The City’s wastewater system is operated as part of its overall Public
Works Department. The wastewater system currently has a total of 3,234
active accounts, of which 2,754 are residential and 480 are nonresidential.

Wastewater treatment is currently provided by three facilities that serve the Old Bisbee, Warren and San Jose drainage basins. The Mule Gulch Wastewater Treatment Plant, which provides treatment for Old Bisbee and was built in 1941, is in violation of effluent limits for various toxic metals and has been unable to meet its pollutant discharge limits on a consistent basis. The Warren and San Jose Lagoons were built in the 1970s and treat wastewater from their respective areas. The Warren lagoons have no liners, and the San Jose lagoons have damaged liners, which allow the percolation of untreated sewage into the aquifer.

Due to age, lack of maintenance, and high infiltration and inflow, much of the City’s wastewater collection and conveyance infrastructure has reached the end of its useful life. Collection systems in Old Bisbee and Warren consist of sewers primarily constructed of vitrified clay pipe in the early 1900's. Problems include: undersized, deteriorated pipes, sections of pipe at grades too steep or too flat, root intrusion, and significant numbers of reported back-ups and sanitary sewer overflows.

Description

The City is proposing a project to mitigate the identified effluent quality problems by correcting the infiltration and inflow problems and providing for a more enhanced treatment process. The proposed project consists of:

  • Rehabilitation and replacement of the most undersized and deteriorated sections of the existing collection system.
  • Construction of a new activated sludge wastewater treatment plant to replace the three existing facilities. The new plant will have increased capacity to accommodate the needs of the community for a minimum of 20 years and will provide preliminary, secondary and advanced treatment, as well as enhanced disinfection.

Benefits

Improvements to the wastewater collection and treatment systems address potentially serious human health and environmental problems by preventing pollution of surface and ground water sources. Replacing and rehabilitating the sewer system will greatly reduce sewage back-ups and overflows, as well as correct infiltration and inflow problems that are overloading the treatment facilities and adversely affecting the quality of the effluent. The new treatment plant will ensure compliance with all federal and state discharge standards.

Project Financing

Total Project Cost US 30.07M
NADB Funding US 11.25M - NADB Grant: BEIF
Other Funding Partners U.S. Department of Agriculture Rural Development (USDA-RD)
Arizona Water and Infrastructure Finance Authority (WIFA)
Border Environment Cooperation Commission’s (BECC) Project Development Assistance Program (PDAP)