Background

Currently, Hermosillo provides drinking water to approximately 98 percent of residents and sewage collection services to 97 percent; however, wastewater treatment is estimated at only 11%. Untreated sewage is discharged into streams west of the city, which eventually flow into the Sonora River. A portion of the raw sewage is also used for agricultural purposes in the Villa de Seris-La Yesca and La Manga irrigation areas.

The City of Hermosillo and the local water utility propose to increase wastewater coverage to 100% of the population through the construction of new wastewater treatment plant. In 2010, local water utility conducted a competitive bid process for the design, construction,
operation and transfer of the wastewater treatment infrastructure and awarded the service contract to a consortium of firms that has created a special-purpose enterprise called TIAR Hermosillo, S.A.P.I. de C.V. to carry out the project.

Description

The project consists of the following components:

Hermosillo Wastewater Treatment Plant
Construction of a plant with the capacity to treat 2,500 liters per second (lps) or 57 million gallons a day (mgd) of wastewater. The effluent quality will meet the parameters established in Mexican standard NOM003-SEMARNAT-1997, for reuse in services in direct contact with the public. The plant includes pre-treatment works and sludge treatment, as well as the construction of two pump stations.

Extension of the Collector Main
Construction of 1.43 miles of 96-inch gravity pipeline to connect the collector system to the plant.

Benefits

This project will reduce environmental and health hazards associated with untreated wastewater discharges, thus providing a cleaner healthier environment for local residents. Specifically, an estimated 45.6 mgd (2,000 lps) of wastewater will be treated prior to being discharged into the environment.