Dunedin City Council, Wastewater Strategy

Dunedin

During 1991/1992, the Dunedin Wastewater Upgrade Strategy was developed by Octa in conjunction with the Dunedin City Council. Octa were then engaged to facilitate the Strategy which included the requirement that the design consultants proceed through an Issues and Options Study, this distilled down to four favoured options where additional work would be completed.

Octa facilitated this process through a Project Working Party, which consisted of 73 members representing various stakeholder groups such as industry, iwi, property owners, schools, environmental groups, Government and Council Representatives. The engineering design consultants were required to firstly educate the Working Party and then to involve them in the decision making process. This had the advantage of often disparate groups seeing and understanding the basis of contrary views. This approach, developed by Octa, was very successful and is the format followed by most local authorities today.

Since the establishment of this Strategy, the following have been achieved:

1992/93 Improved / refurbished harbour wastewater treatment plant
1995 Sawyers Bay wastewater is piped to the new Burke's outfall
1997 The Musselburgh Pump Station was upgraded, including new screens and a major refit of pumps and controls
1999/2000 All Council wastewater discharges into Otago Harbour ceased.
2000 The Green Island plant was upgraded from 1mm screens to secondary and UV disinfection treatment and the often sand covered diffuser of the marine outfall was extended from a point 500m offshore to a rock reef at 850m. This $20 million project comprised each of four contracts: Civil; Mechanical/Electrical; UV disinfection plus Outfall with Octa co-ordinating the interfaces between these contracts
2000 The Mosgiel Wastewater Plant was upgraded and the discharge into the Taieri River was diverted to the Green Island Plant for UV disinfection and disposal offshore through the Green Island outfall
2000 Discussions begin on the upgrade of the Tahuna Wastewater Treatment Plant
2006 Construction of new Tahuna ocean outfall begins
Since 1991 and still ongoing is work related to the control of industrial trade waste discharges. These have improved significantly

As well as developing the initial strategy, Octa’s project management role has been to link the various changing legislative requirements and (related) changing City bylaws.