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Council gives go ahead for 3km pipeline, no artificial UV

29 July 2004

In a unanimous decision today, the Christchurch City Council has given the go ahead for the construction of a 3km Ocean Outfall pipeline to take the city’s treated wastewater out to sea.
It has also decided not to proceed with the building of an artificial ultra-violet (UV) disinfection plant. Provision is however to be made for the possible installation of a UV plant at a later date if water quality outcomes change in the future.
The report to the City Council at its meeting today considered the results of a public consultation process held earlier this year, studies of ocean current modelling and ecology, results from the recently completed upgrades to the oxidation ponds and cost considerations.
Mike Stockwell, the Council’s water and waste manager, says that the recommendations have been made by balancing the technical evidence and the wishes of the community.
“Technically, a 2km pipeline without artificial UV easily meets safe swimming and shellfish gathering standards at the beach. However, community opinion, based on a representative survey of 600 people, favoured a 3km pipeline without UV.
“Participants in the representative survey were required to read the consultation document and represented a cross-section of the city’s residents,” Mr Stockwell says.

Recent results from the treatment plant and oxidation pond upgrades combined with the ocean current modelling were also very encouraging.
“The ponds provide natural UV disinfection and their upgrade is proving to be very effective in reducing bug numbers without additional ongoing costs to ratepayers.
“The ocean current modelling results confirm that a 2km outfall pipeline would easily achieve safe outcomes in the ocean, such as safe to eat shellfish and safe to swim,” he says.
“It’s important that people understand that work either completed or under way at the Christchurch Wastewater Treatment Plant and throughout the city’s sewerage system is already producing a very high standard of treated wastewater.”

Construction of the pipeline is expected to get underway in 2007 and be completed in 2009, depending on how long the planning and consents process takes.

In general terms the pipeline would run from the oxidation ponds at the Christchurch Wastewater Treatment Plant, under the estuary, beneath Jellicoe Street and reach 3km out to sea. It would be buried three-to-four metres deep through the surf zone and a minimum of one metre below the lowest known seabed level.
The cost to build the 3km pipeline would be about $50 million. Adding an artificial UV disinfection plant would have cost an extra $7m and a further $1m a year to operate.

In 2001, the City Council applied for a 15-year extension to continue discharging the city's treated wastewater into the Avon-Heathcote Estuary. That application was based on upgrades to the Christchurch Wastewater Treatment Plant.

Following appeals, however, Environment Canterbury said the estuary discharge could only continue until 2009. The Council needed to find an alternative and, in October 2002, it resolved to prepare an Assessment of Environmental Effects for an Ocean Outfall through a pipeline of no less than 2km.

Pipe route 
After considerable consultation with the South Brighton community and advice from independent experts, the City Council on 11 December 2003 approved Jellicoe Street as the pipe route for the Ocean Outfall.

Key dates

 Public consultation process on water quality and beach standards completed 31 March, 2004
 Christchurch City Council decides at its meeting on 29 July 2004 to build a 3km pipeline without an artificial ultra violet disinfection plant. Provision is however to be made for the possible installation of a UV plant at a later date, if water quality outcomes change in the future
 A complete resource consent application for the Ocean Outfall project lodged with the Canterbury Regional Council (ECan) by December 2004
 The tender for the construction of the Ocean Outfall awarded within eight months of the start of the resource consent
 The outfall operational within 19 months of the tender for construction being awarded.

For a copy of today’s report to the Council see  and see the Report of the Sustainable Transport and Utilities Committee: Ocean Outfall

For more information contact: City Council senior projects coordinator John Moore on 941 8961 or 027 208-5167; or city water and waste manager Mike Stockwell on 941 8332 or 027 435-3322.

For further background information about the Ocean Outfall project see:

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