Timaru District Council has recently completed the Timaru Domestic Wastewater Treatment Plant upgrading project. This project had a capital cost of $19.1M, and is the final stage of the district-wide $60.7M Wastewater Management Strategy.
The Strategy provides for the separation of industrial and domestic wastewater and the construction of new domestic wastewater treatment ponds and wetlands near the existing milliscreen plant at Washdyke. These ponds and wetlands treat the separated domestic flows, including treated wastewater piped from the towns of Geraldine, Pleasant Point and Temuka. High strength industrial wastewater (trade waste) continues to be fine screened (0.75mm) at the milliscreen plant, before combining with the treated domestic flows for discharge to the marine outfall.
The treatment upgrade completed in December 2014, provides an appropriate balance between community financial and environmental aspirations. It focusses on the community’s overall requirement to reduce the public health risks associated with the human component of the wastewater.
This paper describes the process undertaken to achieve an overall consensus on the Wastewater Strategy, the key issues for stakeholders, the consenting aspects of the treatment ponds/wetlands and the outfall, as well as the design and construction challenges and their resolution. The performance of the new ponds and wetlands is also discussed.