Signal Butte Water Treatment Plant expansion strengthens Mesa’s long-term water resilience

Beyond its technical scope, the Signal Butte project is notable for how the project team has navigated construction within an active, essential facility. To complete major tie-ins and critical work, the team planned around two full-plant shutdown windows each year, typically four to eight weeks in the spring and fall. These shutdowns are not guaranteed, however, as they depend on factors such as rainfall, regional water demand, and scheduled maintenance. To manage this uncertainty, the project team worked closely with the City of Mesa to align procurement, staffing, and sequencing plans while also developing contingency strategies.

“A partnership built on communication and careful sequencing allowed construction and plant operations to coexist seamlessly, resulting in 150+ successful tie-ins with zero disruption — a true masterclass in coordination and teamwork,” said senior project manager Oscar Munoz.

That flexibility proved critical when lower-than-average rainfall allowed the team to avoid a planned fall shutdown. Instead, select work—including valve replacements and installation of CO₂ isolation valves—was completed during plant operations using shorter, targeted shutdowns. More complex tie-ins, such as connecting new filters to the existing system, were deferred to a future spring shutdown. The team also demonstrated agility when the City requested that the new reservoir be returned to service earlier than planned. Through daily coordination with suppliers, the reservoir was completed and brought online two weeks ahead of schedule, supporting operational needs without compromising quality or safety.

Cost control and logistics were another defining feature of the project. Limited laydown space initially required hauling approximately 20,000 cubic yards of excavated material offsite, only to later import new backfill. By partnering with the City’s Parks, Recreation, and Community Facilities division, the team temporarily used adjacent park space for material storage, enabling reuse of the original backfill. This approach reduced costs, shortened schedules, and improved overall sustainability.

The project has also faced a highly competitive labor market, with major data center and semiconductor projects underway across Metro Phoenix. To mitigate risk, the contractor coordinated early with local unions, invested heavily in pre-job training, and leveraged self-perform teams across concrete, civil, and process mechanical scopes. This strategy ensured adequate skilled labor during critical shutdown windows and maintained schedule certainty.

As Mesa continues to grow, the Signal Butte Water Treatment Plant expansion exemplifies how large-scale municipal water projects can balance advanced treatment, operational continuity, cost control, and workforce challenges—delivering resilient infrastructure designed to serve communities for decades to come.