Hutt City Council improved the water quality on Wellington's southern coast and reduced the discharge of sewage effluent into the Wainuiomata River.
In 1999 a contract was awarded to treatment plant operator Hutt Valley Water Services (HVWS), a joint venture between New Zealand Water Services and OMI-Beca, and their design build subcontractor Seaview Projects Ltd, a joint venture between Bovis Lend Lease and CH2M Beca.
The contract involved the design, construction and operation of a secondary treatment plant at Seaview in Petone, Wellington, supplemented by ultraviolet disinfection of treated effluent, sludge beneficiation and comprehensive odour control together with new pump stations and a pipeline to transfer sewage from Wainuiomata to Seaview.
The design/build/operate project was both complex and innovative as the plant was built on a low hydraulic gradient to enable the works to be constructed without an interstage pumping station. This saved the client significant capital cost and the equivalent of 440,000kWhs of power per year.
The client also specified that the plant be compact in order to allow future expansion and the interim use of non-plant areas for revenue generation. The plant uses only 4.2 ha of the 9.5 ha available.
Hutt City Council improved the water quality on Wellington's southern coast and reduced the discharge of sewage effluent into the Wainuiomata River.