Challenge
Stantec teamed with PCL to provide design-build (DB) services for the 14.74 mgd upgrade of the Nogales International Wastewater Treatment Plant. The original lagoon-based plant did not meet federal effluent limits and was negatively impacting aquatic life in the Santa Cruz River. Several local citizen and environmental groups had been monitoring the river for years and raised the issue of river quality with the City of Nogales.
Approach
The City of Nogales and International Boundary and Water Commission (IBWC) had tried several times over the previous 10 years to construct a new plant via conventional design-bid-build; however, bid prices consistently exceeded the engineer’s estimate and project budget.
The design-build team managed construction costs using a dynamic cost model and close coordination between the design and construction teams. The dynamic cost model was developed at the proposal stage, and the project team (both construction and design staff) adjusted the design as required to bring the overall capital cost within the owner’s not-to-exceed budget. The team employed several cost-management tools during construction, including BIM modeling. Structural models were set up for the planning and construction sequencing of the main concrete structures, aeration basins, and clarifiers to allow modeling of several different construction approaches. Three-dimensional underground piping models were used to identify potentially costly utility conflicts in advance of construction, therefore minimizing rework and reducing costs.
A comprehensive project partnering approach was used to manage stakeholder concerns and issues for the entire project duration. The DB team developed a comprehensive communications plan at the start of the project and identified each stakeholder’s goals and concerns at the first project partnering session. The design-build team developed an action plan to address stakeholder issues/concerns early in the project and maintained daily communication with the owner’s project manager in this regard. The partnering approach resulted in a conflict-free project with the associated cost and schedule savings. The partnering approach also resulted in a positive perception of the project from all involved.
Results
The project completed by PCL and Stantec delivered this much needed facility both ahead of schedule and on budget. The project’s impact upon the community was immediate. Follow-up sampling in the river indicated several fish species have returned to the area in the vicinity of the effluent discharge. In addition, many of the citizen and environmental groups who monitor the river have complimented the plant operators on the effluent quality and significant improvement in the river’s health.
