The City of Tracy John Jones Water Treatment Plant Expansion includes several new process upgrades to increase plant capacity from 15 mgd to 30 mgd. Carollo completed a preliminary design that recommended process upgrades including new flocculation/sedimentation basins, washwater basins, and chemical addition facilities. Carollo recommended that UV disinfection be implemented to address current and pending regulatory requirements for the inactivation of Cryptosporidium. UV disinfection is a preferred technology for cyst-type pathogen inactivation. For Tracy, UV could be implemented with fewer hydraulic impacts and capital and O&M costs than other technologies, such as ozone.

Carollo also completed final design for the expansion project. As part of the UV design, Carollo conducted a pre-qualification/evaluated bid. The benefit of this unique evaluated bid approach is threefold:

• Selection of the most cost-effective system is based on life-cycle costs, not low-bid capital costs.
• UV system selection considers operations and validation expenses, key elements in the selection of this technology.
• Pre-selection of a single vendor allows the efficient, cost-effective design of a specific system, rather than a "one size fits all" approach.

Carollo evaluated three UV systems manufacturers on the basis of life-cycle cost (capital and O&M costs), reactor validation experience, and installation and operating history. These factors provided a basis for selecting the most preferred UV system.