Mesa's $168M Signal Butte Plant Expansion Nears Fall Commissioning
Mesa, Arizona is doubling the capacity of its Signal Butte Water Treatment Plant to 48 million gallons a day under a $168 million expansion, ENR reports, as the city races to keep pace with growth in the Eastmark tech corridor.
Market Impact
The two-phase project is being delivered as construction manager at-risk, with McCarthy Building Cos. leading construction and Black & Veatch serving as designer. Phase 1, an 8-million-gallon reservoir that added system redundancy, wrapped up in early 2026. Phase 2, which began in summer 2024, is now about 64% complete and carries the bulk of the scope: a 24-mgd capacity boost, sand-ballasted flocculation, ozone generation, six new granular activated carbon filters, upgraded solids handling, added chemical systems and a new sodium hypochlorite generation disinfection process.
Crews are now installing process mechanical and electrical systems ahead of commissioning, scheduled to run from October through the end of 2026. McCarthy project manager Matthew Schmidt says the commissioning phase alone will involve 40 maintenance-of-plant operations to verify equipment functionality. The team also had to navigate a four-month gap between vendor pricing and notice to proceed, a delay that typically triggers cost escalations, but McCarthy project director Oscar Munos says the CMAR structure let the team “secure buyout savings” by keeping trade partners engaged through the gap. Below-average regional rainfall also let McCarthy resequence work with the city of Mesa to avoid a fall 2026 full shutdown, pushing the more complex filter tie-ins to spring instead. The project remains on track for completion in 2027.
What It Means for Subcontractors
- Mechanical, electrical and civil trades still have exposure through 2027: named subs already on the job include Tempe Mechanical (HVAC/mechanical), Industrial Power Solutions (electrical) and Suncoast Post Tension (concrete reinforcing), signaling the type of scopes Mesa and McCarthy are contracting for as Phase 2 closes out.
- Filter tie-in work is now targeted for a spring 2027 shutdown window rather than fall 2026, so mechanical and instrumentation crews bidding on tie-in or valve-replacement packages should track McCarthy’s revised sequencing rather than an original fall timeline.
- Firms with underground utility, shoring or 3D-mapping/laser-scanning capabilities have a track record to point to here: McCarthy’s civil team used potholing and soft-digging methods to navigate congested yard piping after the filter scope grew from four to six units, a model other Arizona municipal water projects may replicate.
- Specialty equipment vendors and installers tied to ozone generation (Veolia Water Technologies) and sodium hypochlorite systems (De Nora Holdings) should expect certificate-of-installation and certificate-of-operation coordination requirements during the October-December 2026 commissioning window.
- Subs working CMAR delivery on municipal water projects should note Mesa’s approach to pricing gaps: early trade partner communication during a four-month pricing-to-NTP delay preserved original costs here, a negotiating precedent worth citing on future CMAR bids.
