Failure risk lowered
Sewer pipes are big money in Porirua, especially with the city council proposing to spend $21 million in the next 10 years to upgrade the ageing system.
This time last year Porirua City Council revealed its plan to accelerate spending to the tune of $2m on the pipes, some of which had never been upgraded since they were first installed.
Inspections and laboratory testing carried out in 2007 saw council officers rate 25 per cent of the pipelines as having an ‘‘extreme-to-high’’ risk of failure.
The council has a target of fewer than 50 incidents relating to blockages per 100km of the network – Porirua has 402km of wastewater pipes – but in 2009/10 the number was 72 and flooding in recent winters in eastern Porirua, Whitby, Takapuwahia and Mana Esplanade has seen the spotlight turned on this aspect of the city’s infrastructure.
Seven years’ work was combined into one, including $1m worth of work in Waitangirua, with much of it to be finished at the end of this month.
This includes the installation of a special liner inside the pipes, a technology not seen before in New Zealand.
‘‘ A lot of the pipes there [Waitangirua] are 40 to 50 years old, they’re really approaching the end of their life,’’ Porirua mayor Nick Leggett said.
The upgrade remains a priority for him as the council approaches the long term plan process.
‘‘ This stuff isn’t sexy but people rely on essential infrastructure to work. Most of us will never see it, unless it’s in a state of disrepair, but we can’t lose sight of the environmental impact of a faulty sewer network if we want to improve our waterways and the harbour. Pipes are the arteries of the city – if they get blocked, it will have a heart attack.’’
In the draft long term plan, Mr Leggett said there would be a proposal to more than double the investment on wastewater in Porirua, from $9.3m to $21m, during the next 10 years.
The strategy is to take the risk level of the pipes failing from ‘‘high’’ to ‘‘medium’’.
Where this extra $ 11.7m would come from was still to be discussed, Mr Leggett said, but it would likely be a combination of cash reserves and loan funding. The next upgrades will occur on the eastern side of the harbour, alongside SH1, from the Porirua train station to Whitford Brown Ave.