Tararua Mayor Tracey Collis, Infrastructure, Climate Change and Emergency Management Committee chairman Kerry Sutherland and CEO Bryan Nicholson met with councillors, staff and members of the public to discuss the latest updates on Dannevirke’s impounded supply.
Tararua Mayor Tracey Collis, Infrastructure, Climate Change and Emergency Management Committee chairman Kerry Sutherland and CEO Bryan Nicholson met with councillors, staff and members of the public to discuss the latest updates on Dannevirke’s impounded supply.
Tararua District councillors have voted to put $900,000 towards the costs of past emergency repairs and the design of future repairs to Dannevirke’s troubled dam.
The councillors were presented with a report at the Infrastructure, Climate Change and Emergency Management Committee meeting last week.
The report covered a brief history of the problem, recent progress, proposed plans to seek a detailed design for the dam’s repair, plans for a workshop to cover other associated issues, public consultation and finance.
Four options have been presented for the troubled dam, including repairing and decommissioning the dam.
Of the four options, option one – remedying the impounded supply - was preferred over option two, monitoring and mitigating the situation, option three, decommissioning the reservoir and constructing alternative storage, and option four, decommissioning the reservoir and constructing an alternate source, storage and treatment facility, with the latter two ruled out because of the urgency of the situation.
Roger Earp: Repairs done in June had been successful in reducing seepage. Photo / Leanne Warr
Since the public meeting last month when the dangerous state of the dam and its emergency repairs were reported, Three Waters manager Roger Earp said another remotely operated vehicle had confirmed the repairs were a success, with seepage down to five litres per second, and constant monitoring has shown the situation had stabilised.
With strong advice from dam specialists to “commence permanent repairs as soon as possible”, councillors were asked to approve $600,000 to finance a “detailed design for full repair of the impounded supply due to a heightened risk of an uncontrolled release and disruption to water supply”.
This involved removing the cover and liner, excavating and replacing subsoil drains, making improvements to dam functionality and safety, including enhancements to hydraulic performance, modifying the inlet structure, installing dam safety instrumentation and laying a new liner.
“These physical works will provide an acceptable long-term solution from all perspectives, including meeting new dam legislation requirements,” the report said.
Decisions on a new floating cover would be made during the design stage and a geotechnical investigation of the eastern embankment would be carried out to assess its condition.
Earp said a further $300,000 was needed to pay for the repairs back in June.
Questions came thick and fast, with councillor Scott Gilmore asking if the report-back date of November 1 was too soon.
Council chief executive Bryan Nicholson said they could not delay it further because the repairs will take five months over the summer to complete, all going well.
Deputy chairwoman Erana Peeti-Webber asked if local contractors would get some of the work.
Earp replied that the need to have someone experienced in “medium dam construction” ruled locals out of much of it.
Councillor Sharon Wards asked if procedures in making the decision for option one had been carried out according to protocol, including public consultation, which was confirmed.
Without a detailed design, only costings of the latter could be given to the meeting, but a very comprehensive list of risks with the project left those present with the impression that this project will be no easy task.
There was a positive feeling among councillors for future consultation with the public, relating to the issues planned for a future workshop next month covering water pre-treatment, additional water storage, a water source for the Alliance and unmetered water users.
Councillor Peter Johns said that consultation “might have to be quick”.
