Innovative technology used to replace sewer pipes

PipeWorks site supervisor Dez Malio, right, shows Rotorua Lakes Council contract supervisor Geoff Kitson how the inversion technology using resin works. Photo/Supplied

Contractors have this week started work on relining sewer mains around Whakatau St using an innovative process called inversion which involves manufacturing new pipes within old pipes using polyester resin.

The $1.03 million wastewater pipe renewal project, which puts a flexible resin liner inside existing pipes, should be completed by next month.

Rotorua Lakes Council contract supervisor Geoff Kitson said because of the process used it should have very little impact on residents.

The method used extends the life of underground sewer and drainage structures without digging up people's lawns or with any lengthy interruptions.

PipeWorks, a Fletcher Construction Company subsidiary, has used the Cured-in-Place Pipe Liner technology throughout New Zealand in both small and large diameter sewer lines, stormwater drains, circular and egg shape pipes.

Much of their work in recent times has been in Christchurch post the 2011 earthquake.

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Initial work in Rotorua involved putting a camera into the pipes to check their structural condition and to identify any impediments such as tree roots, broken pipes and rotten rodents.

Mr Kitson said it was important to get those impediments out of the way, clean the pipes, and make minor repairs before starting the renewal process.

"The primary work, which started this week in Whakatau St, involved putting a flexible resin liner inside the existing pipe. Once the liner is inside the pipe, it will be cured with steam to form a new pipe against the existing pipe."

An example of a tree root impediment in one of Rotorua's sewer pipes

Contractors will monitor the temperature during that crucial period to ensure it stays at around 60 degrees Celsius.

Mr Kitson said it was important to minimise the disturbance to residents so work is being done between 7am and 7pm using construction equipment such as air compressors, generators, boilers and diesel engines.

Some parts of footpaths and roads are also penned off while the work is done.

The polyester resin emits some smell.

Letters have been delivered to all businesses and residents in the area detailing the work plan.