The Casino Mine Corp. has been asked to provide more information about its proposal for a mammoth copper-gold mine northwest of Carmacks.

It’s the second information request by the executive committee of the Yukon Environmental and Socio-economic Assessment Board.

In a letter to the company Tuesday, the executive committee says 449 questions put to the company last January were not fully addressed.

The letter said the assessment board cannot proceed with a screening of the project until it has the information requested.

Tuesday’s information request contains 224 questions pertaining to the tailings facility and dam, road access, traditional land use and the closure and reclamation plan.

“The executive committee has determined that the supplementary information provided by the proponent is still lacking important information and that the proposal remains inadequate for screening,” reads the letter circulated by the board.

The Casino corporation has until early January to provide the additional information, or it can ask the board for more time.

The tailings dam proposed by the Casino corporation – which would be the largest of its kind in the world – has already raised red flags with the Little Salmon-Carmacks First Nation. The First Nation hired an international firm to review the proposal.

BGC Engineering Inc. provided an extensive report to the First Nation last November, and the report was subsequently filed with the assessment board.

The report says there are many outstanding and critical questions that need to be addressed which could affect the technical and financial feasibility of the project.

Among the issues is climate change and how anticipated warming will impact the permafrost on which the dam will be constructed, says the report.

The primary tailings dam would be 286 metres high and 2.5 kilometres wide.

To assist in its review, the assessment board has hired six engineering and consulting firms.

Late last month, the board announced it was also retaining the services of Dr. Norbert Morgenstern, the chair of the B.C. provincial panel that reviewed last August’s catastrophic failure of the Mount Polley tailings dam.

Access to the mine site would require upgrading the existing Freegold Road and building 120 kilometres of new all-weather road.

Concerns have also been raised about the road’s impact on wildlife, particularly the Klaza caribou, which are northern mountain caribou currently listed as a species at risk.

It’s proposed that power for the mine would be a 150-megawatt generating plant fuelled by liquefied natural gas, requiring 11 truck loads of LNG per day.

By comparison, the total generating capacity at the Whitehorse Rapids Dam and across the Yukon is less than 150 megawatts.

The Casino corporation is proposing an open pit operation that would dwarf the former Faro lead-zinc mine.

It would process 120,000 tonnes per day. Faro processed 12,000 to 13,000 tonnes per day at its peak, and the Minto Mine tops out at around 4,000 tonnes.

The cost of building the mine is estimated at $2.5 billion.

The company maintains while it may seem like a lot of money, it’s not out of line with financing provided for other projects around the world of similar size.

Casino president Paul West-Sells has indicated the company has already spent over $20 million advancing the project.