Early Contractor nvolvement Upgrade of Four Water Tretament Plants in Southland

The existing Water Treatment Plants (WTPs) in the Southland District Council (SDC) communities of Te Anau, Mossburn, Otautau, and Winton required improvements to comply with the Drinking-water Standards for New Zealand 2005 (Revised 2008) (DWSNZ). All existing supplies were similar, consisting of shallow bore water sources, primary pumping, and chlorine gas disinfection, followed by secondary pumping into the reticulation where needed. 

Excepting for Te Anau each of the upgrades involved cartridge filtration and ultraviolet disinfection to achieve 5 log credits of protozoa protection. Chlorine disinfection systems, pH correction systems, and building modifications were constructed as required. Each of the upgrades included new instrumentation and control systems to automate these processes and their DWSNZ compliance requirements. 

Downer as the incumbent operations contractor for the existing WTPs negotiated an early contractor involvement (ECI) agreement with SDC to prepare tender designs and prices for each of the upgrades. Subsequently, this led directly into a design and build contract for the upgrade work. This procurement process brought to the project a strong local knowledge of the design risks and the operational experience to recommend operational efficiencies and ensure continuity of supply. Through this procurement process SDC was able to economically and innovatively deliver the four communities with modern, state of the art, WTP upgrades.