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Resource consent applications have been lodged for the proposed $4billion Lake Onslow pumped hydro storage project designed to grapple with New Zealand’s dry-year electricity woes.

The applications made by the Ministry of Business, Innovation and Employment (MBIE) for geotechnical, geological and hydrogeological investigations relate to the New Zealand Battery Project, which has pitched the man-made lake as its most logical anchor. The lake sits above the Teviot Valley, 20km east of Roxburgh.

The proposal would see the existing footprint of the lake raised from 700m above sea level to 760m.

The maximum depth of Lake Onslow is 10m.

MBIE expects to deliver the results of its up to $30million feasibility study on the proposed scheme in May, before making a final decision on its feasibility in December.

The Central Otago District Council (CODC) confirmed it had received two consent applications geotech, bore hole and test pits had been granted.

A second application was formally received on Friday for similar matters.

CODC could not advise the number of consents required, as the evolution of the project and its feasibility would determine that.

MBIE manager energy projects and programmes Andrew Millar said the ministry commissioned the Department of Conservation to undertake a comprehensive study of environmental, recreational and conservational values at Lake Onslow and its surrounding area last year.

“A major part of this study involved subcontracting experts to conduct field surveys, including activities such as sampling streams for native fish and insects and walkover botanical and ecological field surveys of birds and lizards and other species.”

MBIE also commissioned Niwa and the Cawthron Institute to conduct studies into the hydrology and ecology at Lake Onslow and how these could change if a pumped hydro scheme was to be developed, he said.

Studies included looking at water quality, the fishery, the lake’s productivity, biosecurity and also modelling how a much larger lake with fluctuating water levels may behave.

“A monitoring buoy in the lake and a meteorological station on Mt Teviot are providing data in real time.”

Preliminary walk-over fieldwork was conducted over spring and summer, with MBIE commissioning independent experts to assess the ecological and cultural values of the proposed lake’s larger footprint.

“The focus of our fieldwork is now shifting to the detailed geotechnical, geological and hydrogeological components of the feasibility study focused on the area around Lake Onslow,” Mr Millar said.

He said that work was required to understand things like regional geology, rock properties, faulting and groundwater interactions with surface water.

Applications for the necessary consents and permits were in process, as well as meeting other required pre-work conditions.

Once granted, core samples of schist would be extracted for analysis and equipment installed down boreholes to monitor groundwater levels and pressure.

“We’re also proposing to excavate test pits to sample earth near the surface level, undertake non-intrusive surface seismic surveys and test rock samples.”

The New Zealand Battery Project was investigating the feasibility of a range of possible solutions to address the dry-year problem, which was when hydro electricity lakes received insufficient inflows and New Zealand had to burn fossil fuels to make up the shortfall.

Other possible solutions such as smaller pumped hydro schemes at other locations, other hydro options, and the five alternative technologies including bioenergy, hydrogen and new ways of using geothermal were also being investigated, Mr Millar said.

The feasibility study was expected to be completed by year’s end, including fieldwork.

“At this point, ministers will consider the feasibility of all options investigated and decide on which option or combination of options to take through to the project’s next phase and develop a detailed business case.”

MBIE would also report to ministers in the coming months, Mr Millar said.

This is an opportunity for ministers to consider early findings and make decisions on the focus of the remainder of the feasibility study.

The resource consents formed part of a broader picture.

“We generally require resource consents and sometimes wildlife permits for detailed geotechnical fieldwork, depending on the nature of the fieldwork.

“We have applied for, and received, some of these.”

Consents were being applied for in stages, depending on the planned timing of the associated fieldwork.

“Not all consents that are applied for or granted will necessarily be needed, but it’s important to have this flexibility if required.”

Resource consents were lodged with CODC and Otago Regional Council, and wildlife permits were lodged with the Department of Conservation, some of which had been approved, he said.

“The approved consents come with conditions, which we are working through now.

“The work cannot commence unless these conditions are met.”

That said, some fieldwork had begun, Mr Millar said.

“For example, environmental and hydrological fieldwork at the lake began in May last year, paused over winter and then resumed in September.

“The environmental field work is now mostly complete.”

If pre-work conditions could be met, the first part of the detailed geotechnical investigation could start in the coming weeks.

“We will be sharing more information with the local community as soon as we have certainty on this work.”

Fieldwork took place on both public and private land and MBIE had been talking directly with affected landowners to gain approval for field work on their property.

“Landowners have been responsive to this engagement.”

Mr Millar said MBIE appreciated exploratory work created uncertainty for the local community, but more work, including geotechnical investigations, was required to determine what locations may be appropriate for the dam and tunnel route.