Treated wastewater discharges into Lyttelton Harbour are set to end with the construction of submarine pipelines that will carry sewage from Diamond Harbour and Governors Bay to Lyttelton.
From there the sewage will be pumped through the Lyttelton road tunnel to a pumping station in Woolston and then across to the Christchurch Wastewater Treatment Plant in Bromley.
The scheme will cost about $50 million.
Te Hapū o Ngāti Wheke, who have been pushing for wastewater discharges into the harbour to end for cultural reasons, supports the new scheme and Environment Canterbury has already granted the necessary resource consents.
Currently wastewater from Lyttelton, Governors Bay and Diamond Harbour is treated at wastewater treatment plants in each of the townships before being discharged through outfall pipelines into Lyttelton harbour.
Engineering consultants Jacobs are currently working on the detailed design of the scheme, which will be split into four projects for construction purposes.
Christchurch City Council is currently preparing a procurement plan for the delivery of the physical works, which is likely to span a five-year period.
The new submarine pipelines will be buried approximately 1 metre deep into the seabed, which is sufficiently deep to prevent anchors catching or the pipes being damaged in storms, tsunamis or earthquakes.
NIWA will begin surveying the pipeline alignments from Governors Bay and Diamond Harbour to Godley Quay early in the new year.
Council Head of Three Waters and Waste John Mackie said the scheme was the end result of years of hard work by a community-led working party that had explored all sorts of options for ending wastewater discharges into the harbour before reaching the conclusion a submarine pipeline and discharge to Bromley was the best option.
“It’s taken a number of years to get everything lined up but there is now across-the-board agreement this is the best way forward which means we can now move into the construction phase,’’ Mr Mackie said.