THEY'll be hauling 600 metres of high-density plastic pipe under the Whanganui River today in an ingenious engineering manoeuvre that will mean considerable savings for the city's massive wastewater scheme.
The 1m-diameter high-density polyethylene pipe will be inserted into the existing concrete pipeline that stretches from the Beach Rd pumping station
to the river end of Wanganui's airport.
It replaces the concrete line, which is not strong enough to handle the high pressures that will be needed when the new system is commissioned.
The new pipe will float inside the concrete line carrying waste from Beach Rd to the new treatment ponds being built behind the airport.
Julian Reweti, Wanganui District Council infrastructure manager, said this was a "highly technical and challenging engineering project" and he believed that it was the largest pipeline to be pulled through another over the longest known distance.
To be able to carry out the work, the city's wastewater will be discharged into the Whanganui River until April 14 Excavations were carried out on both sides of the river to expose and cut into the existing pipelines while the plastic pipe was welded to form one long 600m string on the South Beach side of the river.
Last week a small test section of pipe was pulled through part bends in the river crossing.
Mr Reweti said that, "all being well," the new line should be pulled through by this evening and pressure tested on Friday.
