Proposals to establish a new water supply for Twizel, already estimated to cost as much as $5.6 million, may end up costing even more.
The Mackenzie District Council proposed in its recent draft annual plan for 2013-14 to spend between $2.1 million and $5.6 million to either upgrade the township's water source, from a bore next to the Fraser Stream, or create a new bore 3km to the west, near Ben Ohau Station.
The plan said rates in Twizel would rise by more than 8% to help pay for any required work.
However, a recent test at a proposed new bore site revealed the presence of iron and manganese, both of which would require a treatment plant to be built so they could be removed.
Council assets manager Bernie Haar said although two test bore holes had been drilled two months ago, neither returned the best of results.
''One didn't show up sufficient water quantity, the other had some issues with [water] quality that will require some extra treatment. So we are discussing that with our consulting engineers to see what the cost of carrying out that ongoing treatment is.''
He added that the capital cost of upgrading the bore, which had operated since the 1970s, would be less than that of establishing a new bore, but the council already spent about $40,000 a year in energy costs to pump water from the Fraser Stream site and operating costs would be higher if that supply was upgraded, because it did not supply newly zoned land to the west of the original Twizel settlement.
That meant ''further pumping'' would be required on a continual basis to reach any new properties to the west, he said.
''The whole treatment plant itself is coming to the end of its useful life, hence the need to work out a solution, because clearly, if we start rebuilding the existing system, then that's what we will be locked into.
''The council's preferred option is to have a new source, closer to the hill behind the Cameron homestead [Ben Ohau Station] and pumped from that into a new reservoir on the hill and then gravitate down to the town, because that would provide the best solution for the community ...''
The council would ''review'' its options with consultants next week and assess if it was still committed to finding a new source for Twizel's water supply, he said.
