Val Vista Water Treatment Plant
Scheduling is Crucial to the Construction of the Val Vista Water Treatment Plant
Carollo provided design and construction management services for the upgrade and expansion of the Val Vista Water Treatment Plant, jointly owned by the Cities of Phoenix and Mesa. Carollo’s involvement with the Val Vista plant began with the design and construction inspection services for the original 80-mgd treatment facility, placed into service in 1975. Recent upgrades bring plant capacity to 220 mgd. Design and construction of the latest upgrade/expansion took place in two phases.
Project Elements
The first phase was a hydraulic and instrumentation upgrade. This phase consisted of filter modifications, a new chemical handling facility, modifications to the electrical and instrumentation systems, reservoir modifications, a new used water recovery and solids dewatering system, and miscellaneous plant improvements to bring the plant into compliance with key regulatory guidelines. This provided for more reliable and efficient plant operation.
The second phase, designed as the first phase was constructed, increased plant capacity by 80 mgd. This phase included new water inlet facilities; a raw water pump station; presedimentation, flocculation, and final sedimentation basins; monomedia filters; expanded chemical handling facilities; chlorine disinfection facilities; administration building modifications; and expanded distributed control sytem instrumentation.
Tie-ins are Key
The plant produces the lowest cost drinking water for the City of Phoenix. Thus, a major consideration was to maintain operation during construction. The team scheduled all tie-ins to the existing plant during two one-month annual shutdowns and worked closely with plant staff and the contractor to verify tie-in preparations and procedures. Properly scheduling shutdowns allowed work completion without unnecessary loss of plant production capacity.
Team and Services
Carollo’s construction team consisted of a construction manager, a full-time and assistant resident engineer, a construction scheduler, and inspectors for each of the major process areas. The construction management staff used a proactive approach and state-of-the-art equipment/software to track and store documents. Expedition software provided a means of logging/tracking all documents, including shop drawing submittals, progress payments, requests for information, change orders, and claims management/avoidance documentation. Carollo and subconsultants provided bidding, project management, inspection, and commissioning services for the new plant. The team completed plant start-up and operation in both manual and fully automatic modes before turning the facility over to the operations staff for production. Commissioning of the plant resulted in a minimal need for warranty work after plant start-up.
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