Two options chosen for Alexandra water

01:35, Dec 13 2013

Alexandra ratepayers will have to decide how much clean water is worth to them.

Central Otago District Council development engineer Peter Morton told the council at its meeting on Wednesday that several years of work had gone into investigating options for improving the Alexandra water supply, which currently did not meet drinking water standards. It had problems with scaling, hardness and taste and odour issues, as well as being close to a closed landfill and mine.

After exhaustive technical work there were two sets of options for the council to consider and put out for public consultation, he said. The minimum lower cost option of disinfection treatment to bring the existing site up to drinking water standards, at an estimated cost of $8.5 million, with an operating and maintenance cost over 20 years of $14.59m.

This option does nothing to address the scaling or hardness of water, or risks from the nearby closed landfills and old coal workings.

Establish a new Clutha River or Lake Dunstan water source sized to service Alexandra alone at an estimated cost of $11.5m to $14.5m, with an operating and maintenance cost over 20 years of $16m to $21m respectively.

This option would meet drinking water standards, address the closed landfill and mine workings risks and would provide softer water with reduced scaling similar to Clyde.


Ratepayers paid an annual water charge of $249 per year. To fund the upgrade, that would increase to $550 for the minimum cost option and $650-$800 for the new source option.

Mr Morton said on the surface the Lake Dunstan option appeared to be the most economic, however, its feasibility had not been "technically proven".

Trial bores would need to be installed to investigate the feasibility of supplying Alexandra from the Lake Dunstan shoreline gravels near the Clyde water intake, costing an estimated $110,000, he said.

The council will carry out testing.

"By June 2014 will know whether Lake Dunstan is feasible supply or whether it will be discarded and you are just left with the Clyde supply," Mr Morton said.

The Southland Times