Treatment Plant in Mesa, Ariz., Receives Fast-Track Upgrades
The 1974-vintage, 220-million-gallons-per-day Val Vista Water Treatment Plant needed an upgrade to meet increasingly stringent federal water quality standards and to protect public health.
The rules required that the plant remove disinfection by-product precursors during treatment, so the city of Phoenix elected to use post-filter, granular-activated carbon, or GAC. Designed and constructed in 27 months, the $84-million GAC facility reduces the plant's footprint and minimizes future maintenance costs and operational complexity while maintaining the city's flexible use of the plant.
"Most fast-track projects jump out of the gate without a fully conceived game plan," says one Best Projects judge. "This team seems to have put in place a solid road map and then executed on it."
The project team was required to tie in the plant's new systems during its annual eight-week shutdown period.
"The work required thorough planning, careful preparation and, most importantly, a high level of trust that team members could provide the resources and expertise required to complete the work within the time constraints," says Mike Schlabach, project manager with Sundt Construction.
To complete tie-in of the below-grade bypass structure during the brief shutdown window, crews first built most of the bypass around the existing box conduit's structure tie-in. Then the contractor installed a new sluice gate in the existing box conduit and removed portions of the existing structure.
Also during the shutdown, contractors completed the major electrical tie-ins, relocated the plant's potable water source supply line, installed chemical feed diffusers and added sample supply lines.
To optimize the plant's transition to the new systems, crews created and performance-tested a parallel control system with the newly constructed equipment before merging it with the existing plant control system.
Using value engineering and a phased design and construction schedule, the project team shortened the schedule and reduced the project's cost by $5.6 million.
Contractor: Sundt Construction Inc., Tempe, Ariz.
Owner: City of Phoenix
Lead Design: Black & Veatch, Phoenix
Subcontractors: Coreslab Structures, Phoenix; CS & W Contractors, Phoenix; Keller Electrical, Phoenix; McCarthy Building Cos., Tempe, Ariz.; Sturgeon Electric Co., Tempe, Ariz.
Submitted by Sundt Construction
Award of Merit, Civil: Hawthorne Utilities System Rehabilitation