Well met sewer tunnels completed

JOHN BISSET/ The Timaru Herald

FINNISHING TOUCH: Council contractors Phillip Burns, left foreground, and Sean Riley check out the completed sewer tunnel.

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The final tunnel in Timaru's sewer main renewal project has reached a breakthrough.

Council contractors bored through to meet up under the Westcott and Richmond St hill. The tunnel, about 400 metres long, bored at depths of between four and 19m and 2m in diameter, is the last of three to completed.

Boring began in February with two crews working from the north and south ends.

Timaru District Council drainage and water manager Grant Hall said the tunnels were well aligned when they met.

However, work had been disrupted when the boring machine, working from the Ashbury Park end, hit a mix of basalt, clay and rock a couple of weeks ago.

Contractors also hit problems in April when they struck another tunnel with a functioning sewer pipe in it.

Mr Hall said preparations had been made for slight holdups as there was more rock to blast and drill through than expected.

Crews continued working with drilling gear and explosives.

Recovery of tunnelling machinery is now under way, including the removal of railway lines before contractors start on the next stage of the project.

Harker Underground Construction will pour a concrete floor in the tunnel before installing steel brackets to the roof which should support two pipelines.

Stage four of the main trunk sewer is under way, with Downer EDI Works linking the pipes between the tunnels.

Work on the sewer replacement programme has to be completed before 2010 when its right to discharge sewage into the sea expires.

- © Fairfax NZ News