Pima County Tres Rios Wastewater Reclamation Facility

Location: Tucson, Arizona, United States

Region: Americas

Market Sector: Water & Wastewater

Status: In Progress

The $225M construction project consists of:

• Expanding preliminary and primary treatment facilities from 37.5 to 50 mgd
• Constructing a new 25-mgd ammonia/nitrogen/nutrient removal process system (5-stage Bardenpho) to replace an existing 25-mgd HPO train
• Upgrade modification to existing 12.5-mgd BNRAS process train for additional ammonia/nitrogen/nutrient removal process system
• Constructing a new 12.5-mgd capacity ammonia/nitrogen/nutrient removal process system
• Modifying effluent disinfection facilities using sodium hypochlorite technology followed by de-chlorination
• Constructing interim biosolids digestion and thickening improvements
• Constructing biosolids facilities for additional sludge from an offsite 25-mgd water reclamation plant
• Constructing miscellaneous ancillary support system improvements
• Repairing and replacing wastewater equipment and structures
• Expanding biosolids processing
• Adding odor control measures
• Upgrading the facility to be compliant with environmental, regulatory and building code requirements

MWH is self-performing approximately 50 percent of the work. MWH maintains exclusive control of the entire mechanical process equipment critical path, from procurement through operations. Our self-performance strategy is focused on the undivided ownership of the most complex aspect of the work, best ensuring an on time start up and completion.

While many CMAR contractors focus their self-performance on structural concrete, we know that is only half the path. Even though structural concrete does fall on the critical path during the initial phase of the work, the critical path ultimately runs directly through delivery of long lead equipment, mechanical process equipment setting and commissioning, instrumentation and controls and plant start up. To maintain maximum schedule and quality control, we self-perform the process equipment procurement, installation, instrumentation and control, and commissioning and start up.

The unfragmented control of late phase critical path activities provides the client with single point accountability at the place in the project most commonly responsible for the largest progress delays.