Wastewater options put to residents

23:49, Oct 08 2012

A public health risk posed by Cromwell's wastewater treatment may mean an urgent upgrade of the system, with ratepayers asked to choose between $9 million and $17m options.

Central Otago district's capital works programme manager, Peter Greenwood, said dye-testing in the Kawarau Arm of Lake Dunstan in February this year revealed effluent mixing 600 metres downstream of the wastewater discharge, at a level that failed to meet bathing water standards.

A report compiled over the past four years by the Cromwell wastewater working party said Cromwell had outgrown its wastewater treatment plant "and it no longer performs to modern standards".

Cromwell's wastewater is currently screened before entering a seven-hectare treatment-pond area where it remains until wave action and sunlight broke down the waste to a point where it could be discharged to Lake Dunstan.

Ponds built more than 30 years ago for a peak population of 9000 as part of the Clutha Valley hydro development upgrade can no longer cope with the town's growth. The report also said environmental expectations were now much higher and carried greater authority. Tourism and viticulture were factors in the increased demand on the wastewater system. Pressure was mounting to improve discharge qualities before interim consents with the Otago Regional Council for both the Cromwell and Bannockburn wastewater systems, operating since the early 2000s, ran out in December next year.

Cromwell Community Board has shortlisted two options: an enhanced filtration-settling system that would cost about $9m to install, and an advanced biological treatment system with a capital cost of $16.7m.


Community board chairman Neil Gillespie said doing nothing was not an option. "It would be easy to simply choose the cheapest option but when you look at the figures in the long term it might not end up being that way.

"I believe environmental standards and community expectations are only going to get higher in the future, so we might be better to spend the money now than take the cheap option."

Public feedback is invited from tomorrow until November 2.

Hard copies of the communication are available from the Cromwell Service Centre and Cromwell Library, or can be downloaded from the council website. Comments can also be made online at http://consult-codc.objective.com/portal.

The Southland Times