Research supports right water options

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Central Otago District Council executive manager, infrastructure services, Julie Muir explores several water issues in a response to a previous column by Alexandra man Gavin Dann.

All decisions made by the Central Otago District Council around our local water and wastewater are based on robust research and community consultation.

DEVELOPMENT

Development in our district is not a “cash cow” for councils and there is no financial windfall because of it. Costs of development on existing infrastructure are met by developer contributions.

DISCHARGING LIQUID WASTE

Council staff continually monitor technological advances in the treatment of wastewater locally and internationally, including options for sustainable reuse of treated wastewater.

In Mr Dann’s comment about discharging liquid waste to land, the previous consent for the Alexandra wastewater treatment plant required the council to investigate new and alternative technologies that have become available since the granting of the consent (including land-based disposal options), by June 1, 2033.

As a consequence of bringing stage one of the Clyde wastewater to Alexandra, the date for this review has been brought forward to 2026, with construction commencing in 2029. If growth in Alexandra is greater than forecast, this will be reviewed sooner.

wastewater from septic tanks in Clyde is having an adverse impact on groundwater quality within the area, which then flows into the Clutha River. The council did consider establishing a separate wastewater treatment site at Clyde, with disposal of the treated effluent to ground at Muttontown. This was discounted due to the negative impact it would have on groundwater and residential bores.

The transfer of wastewater from Clyde to Alexandra, where it will be treated prior to discharge into the river, will deliver significant environmental and public health improvements compared to the existing septic tank discharges.

LAKE DUNSTAN WATER SUPPLY

The existing Alexandra bore field is downstream of the old Alexandra landfill site and industrial area. The new site is upstream of a modern, much smaller landfill site that has been sealed with a 500mm clay seal to avoid any possible leakage.

Council engineers are confident that this does not pose a threat, otherwise the site would not have been chosen.

ALTERNATIVE BORES

Mr Dann commented about “very good bore fields near Dunstan High School”. It’s incorrect to assume these are safer than a surface water source or the proposed bore site at Clyde. Unfortunately, there is a common misconception that groundwater is safe, and the contamination incident at Havelock North is evidence of this. Groundwater sources were investigated in both Dunstan Golf Course and Earnscleugh areas by experts. These were unsuitable because the water was similar in hardness to the current Alexandra water source, and they are unlikely to provide the quantity or quality of water required.

Over the past 27 years there have been numerous investigations, reports, studies, and consultation carried out to ensure the right decisions continue to be made to sustainably improve the quality of our local water and wastewater.

Community feedback has been largely positive for the planned Alexandra pipeline, which we are confident will deliver safe, healthy drinking water not just for today, but for future generations.