McCarthy Pushes Forward on Mesa’s $168M Water Plant Expansion

The Daily Dig:

McCarthy Building Companies is deep into construction on the $168 million expansion of the Signal Butte Water Treatment Plant in Mesa, Arizona, with the first phase now reaching a critical point. The work includes a new eight million gallon finished water reservoir built next to an existing tank, all while the plant stays online. One of the standout features is a subsurface leak detection system installed beneath the reservoir, designed to flag and locate leaks early. This is a practical response to the area’s soft soils and long-term maintenance concerns.

The team is also managing deep excavation and complex shoring, staging roughly 20,000 cubic yards of excavated material nearby to limit haul off costs. Early planning shaved about two months off the schedule, a rare win on a municipal water job with this many moving parts.

Project Snapshot:

• Owner / Developer: City of Mesa, Arizona

• General Contractor: McCarthy Building Companies

• Engineering Team: Black & Veatch

• Sector: Water infrastructure / treatment

• Value: $168 million

• Location: Mesa, AZ

• Timeline: Phase one completes October 2026; phase two early summer 2027

TheJobWalk Thoughts:

This is what resilient infrastructure actually looks like. Not flashy. Just smart planning, redundancy, and systems that assume problems will happen and prepare for them anyway. Building a reservoir with leak detection baked in isn’t overengineering, it’s acknowledging reality in desert ground conditions where water loss is not an option.