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6 December 2021

The Citycare Water Construction crew laying new drinking water pipes for the Christchurch City Council (CCC) near Lyttelton are constantly solving challenges as they progress from Cass Bay towards the port over coming months.

It’s a beautiful work setting overlooking Lyttelton Harbour, but the geology can present a challenge, just as much as a wide load vehicle travelling through the site from the port to Christchurch because it won’t fit through the road tunnel.

The team currently have a rock breaker on a 12-tonne digger creating the trench for the new pipes as solid rock slows down their progress near Corsair Bay.

They are working cliff-side on the narrow road between Lyttelton and Governor’s Bay and dealing with the terrain as they go, Citycare Water Three Waters Supervisor Cory Gibbons says.

Subsidence is another challenge, with parts of the ground under the road surface providing surprise hollows and gaps which need to be filled in, he says.

Traffic management is an essential part of the project so residents, travellers and workers are kept safe while the road is one-way and controlled by traffic lights and a reduced speed limit.

A specialist Site Traffic Management Supervisor (STMS) is present whenever the Citycare Water team are working and the traffic controls are checked at the weekends, too.

A usual day sees four wide load vehicles traverse the route, shutting the site down momentarily while the truck creeps around the 500-metre work area, Cory says.

The other traffic is halted and the Citycare Water crew, led by the STMS, usher the wide load vehicle through by moving cones and equipment aside to provide safe passage.

Replacing and upgrading the existing water supply mains and lateral connections is part of renewal work for CCC as that area of the network has reached the end of its lifecycle.

As the Citycare Water team progresses each day, the old pipes are left buried underground and eventually the new 250mm PE pipes will be cleaned, flushed and tested before the drinking water supply is switched over, Cory says.

Team members have specialist qualifications and are registered to lay pipe. They use specific machinery to undertake their work.

One example is the surface road locator which x-rays the ground to record where services run to households so they can be potholed, marked and left undisturbed.

Another example is a road saw used to cut the existing asphalt road surface.

The pipe is laid in flexible sections which are electrofusion welded together and screwed and bolted when fire hydrants are part of the underground connection. The longest section so far has been 66 metres, made up of multiple 12-metre pieces, Cory says.

Once the pipe is in place, the trench is backfilled with base metal (shingle) and compacted, using another specialist machine – the compactor – before the road is sealed again, he says.

When each 500-metre section of the new pipe is completed, Water Drainage Foreman Jason Stenton organises the team to move the traffic management further along and continue their work.

This project is expected to take until July 2022.


Lyttelton 6

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