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Unexpectedly difficult ground conditions have caused significant delays on Temuka’s Domain Ave sewer renewal and upgrade.

The $1.3 million project involves replacing the 1930s clay pipe along Domain Ave with new pipe, installed up to a metre deeper in the ground to improve the gradient in the network as it feeds into the wastewater treatment plant on the river side of the Temuka Golf Course.

Timaru District Council drainage and water manager Grant Hall said the work had been straightforward from the treatment plant across the golf course and along Domain Ave from Murray St, but contractors Hadlee and Brunton had struck problems in the Hayhurst St area.

“They’ve struck some really dry, fine gravel, which just falls into the excavations, and that’s slowed progress to about quarter of the rate they were doing beforehand.

“They’re now doing one 6m pipe per day, when it was four or five times that rate.”

Mr Hall said a lot of infrastructure work had been carried out along Domain Ave over the years, but these ground conditions had never been encountered before.

“Clearly, there will be some additional costs that the council has to wear, in terms of the unforeseen ground conditions, but there’s a bit of contractor risk as well. But all that’s still to be finalised.”

Sheet piling was required in order for work to continue, but the project was now running well behind time. The original estimate was for work to be completed by August.

That was also holding up land transport unit plans for a major reinstatement of Domain Ave, from kerb to kerb, although work on one section was about to begin.

Mr Hall said the council was changing the design in order to speed up work on the part of the project from Hayhurst St through to Studholme St.

While work done so far was along the middle of the road, the rest of the pipe would be laid along the alignment of the existing sewer, on the north side of the road.

He hoped to have the work completed within five to six weeks, and with the possibility of using trenchless technology, there would be less effect on the road.