The city of Nogales, Arizona’s International Wastewater Treatment Facility project was recently named one of the Public Works Projects of the Year by the American Public Works Assn. (APWA). The project’s managing agency, the city of Nogales, along with primary contractor PCL Construction Inc., and primary consultant, Stantec Consulting Services Inc., will be presented with the award during APWA’s 2010 International Congress & Exposition in Boston from Aug. 15 to 18, 2010.
The APWA Public Works Projects of the Year awards are presented annually to promote excellence in the management and administration of public works projects, recognizing the alliance between the managing agency, contractor, consultant and their cooperative achievements. This year, APWA selected 18 projects in five categories: Disaster or Emergency Construction, Environment, Historical Restoration, Structures and Transportation.
Awarded in the Environment category, with cost between $25 million and $75 million, the city of Nogales and the International Boundary and Water Commission (IBWC) initiated a coordinated public works response following a court order for failure of the existing lagoon-based facility to meet effluent requirements for the Santa Cruz River discharge. Involved in the project were a large number of stakeholders and agency decision makers, including the U.S. Environmental Protection Agency, the Arizona Department of Environmental Quality, the city of Nogales, U.S. Section of the IBWC, Border Environment Cooperation Commission and North American Development Bank. The strong cost control and proactive stakeholder management were both keys to the project’s success, according to APWA.
The two most significant challenges on this project included the limited project budget and management of the large and diverse stakeholder group. The PCL Construction team was the only team to provide a solution that met the constrained budget requirements. Other challenges included a change in influent characteristics impacting the process performance, which had a significant impact on nitrogen removal. The design-build team was able to identify a solution, however, that included the design of a carbon supplementation system for de-nitrification. This carbon system uses waste from a biodiesel facility and is both environmentally sustainable and cost effective.
In addition, the design-build team was required to incorporate principles of green building design, as outlined in the Border Environment Cooperation Commission’s guidelines for green building practices. Areas that included the green building practices in the facility design included the planning, earthwork/erosion control/site drainage, backfill, site paving, landscaping, concrete, and special construction.
Some of these practices included treated effluent onsite, separating clay and native fill material during construction to allow both to be used for dike and backfill material, use of gravel finishes eliminating need for landscape irrigation, minimizing the use of import fill and employing as much common wall construction as possible to minimize concrete use.
The resulting impact on the community has been immediate. The U.S. Geological Survey has conducted follow-up sampling in the river indicating a number of fish species have now returned to the area in the vicinity of the effluent discharge. In addition, many of the citizen/environmental groups that monitor the river have complimented the plan operators on the effluent quality and significant improvement in the river’s health.