Earthquake damage to pump stations and pipelines in Kaiapoi and between Pines Beach/Kairaki and the sewerage treatment ponds are hampering Waimakariri District Council efforts to stop river discharges.
The Charles St pump station on the northern side of the Kaiapoi River that services a large part of the town is expected to be operational later this week once the broken pipeline to the sewage treatment ponds is repaired.
Council Chief Executive Jim Palmer said the pump station on the southern side of the river which pushes waste water along a pipe under the Kaiapoi River to the Charles St pump station had been cleared and was functioning reasonably well until a couple of days ago.
The flow through the pipeline has now slowed from around 70 litres a second to 15 litres a second, indicating a significant break.
“Now it’s become obvious that the pipeline needs to be repaired or replaced. It will be some weeks before we can fix the break under the river and so we’re going to need to continue discharging sewage from the south side into the Kaiapoi River at Raven Quay near Bowler St,” Mr Palmer says.
It would also take at least another month to fix the pipeline between Pines Beach/Kairaki and the treatment ponds as well.
“In the meantime, we’re needing to continue discharging effluent into the lower Waimakariri,” Mr Palmer says.
About 150 Kaiapoi households and around 50 from Pines Beach and Kairaki were still affected by sewer system problems.
“For those people, it’s likely that we’re going to need a temporary solution for some weeks or months. Yesterday we wrote to all 200 households outlining the situation and inviting them to a public meeting tomorrow night at 7pm at the Kaiapoi High School auditorium. We’ll discuss reticulation issues and possible solutions that will be worked through with each homeowner over the next couple of weeks.
“Around 95% of Kaiapoi has a functioning sewer system. If residents haven’t received this letter, we are reasonably confident that they are able to use their toilet and shower as per normal. We are still encouraging people to be conservative with their water use. The less waste water we have to deal with while we’re fixing these reticulation issues, the better.”
Mr Palmer says while the Council staff have been working seven days a week to return services to a level of functionality, it was still going to take months and maybe a year to rebuild all the sewerage reticulation systems.
“This has been tough on affected residents and we have really appreciated their patience. It’s not ideal, but there is still a lot of work to do,” he says.
In the worst affected areas gravity mains are two or three metres deep. Combined with the high water table, this means when work needs to be done, trenches have to be sheet-piled and dewatered to allow workers to fix pipes.
“The estimated costs are between $500 and $1000 a metre – it’s expensive and takes a long time. We have engaged additional engineering staff and consultants because we realise there might be some alternative options that will end up with a better result for our sewerage reticulation, but we’re balancing that with the need to get the system up and running as soon as possible.
“The sewerage reticulation is our first priority because it needs to be reinstated before anything else, like telecommunications systems and roads which are layered on top,” Mr Palmer says.
The meeting for Kaiapoi, Pines Beach and Kairaki residents without functioning sewerage systems takes place at the Kaiapoi High School auditorium tomorrow night at 7pm.