TORONTO (miningweekly.com) – The proponent of the Back Forty project in Michigan expects to apply for regulatory permitting before year-end.

To this end, TSX-listed Aquila Resources confirmed on Friday that it had filed a letter of intent with the Michigan Department of Environmental Quality (MDEQ).

"Our focus in the coming months will be to work closely and collaboratively with local stakeholders, government representatives and advisors to ensure that our permit application is completed on a timely basis and is clear, comprehensive and fully compliant with Michigan's environmental regulations,” CEO Barry Hildred said on Friday.

Aquila also planned to submit the linked air, water and wetland permit applications in with the mining permit application.

The company had hired local engineering firm Foth Infrastructure & Environment to assist in the preparation of the permit applications. 

Foth had worked on the Back Forty project since 2006, conducting a series of technical studies, including waste rock geochemistry and tailings, bedrock hydrogeology, water treatment, groundwater modelling, air quality and deposition modelling, reclamation planning and the tailings and waste rock storage facility design. Founded in 1938, Foth had also managed a consulting team that conducted baseline environmental studies at Back Forty.

A new preliminary economic assessment (PEA) completed on the Back Forty project, in Michigan’s upper peninsula, incorporated a revised mine plan based on results from Aquila’s 2013 resource update. The project contained measured and indicated resources of 15.13-million tonnes, grading 2.03 g/t gold, 24.48 g/t silver, 0.33% copper, 0.22% lead and 3.06% zinc. Inferred resources totalled 2.34-million tonnes, grading 2.07 g/t gold, 26.53 g/t silver, 0.36% copper, 0.33% lead and 2.2% zinc.

The PEA contemplated mining 16.1-million tonnes of mineralised material over the 16-year life-of-mine, of which 12.5-million tonnes were openpit and 3.6-million tonnes were underground.

The PEA had demonstrated the potential for a diverse earning stream, with a payable metal value mix of 41.2% gold, 40.5% zinc, 12% copper, 5.7% silver and 0.6% lead. Operating at an initial throughput rate of 5 350 t/d, the total payable production of the mine was expected to be about 532 000 oz of gold, 704-million pounds of zinc, 63-million pounds of copper, 4.66-million ounces of silver and 11-million pounds of lead.

The $261-million Back Forty project had a net present value at a 6% discount of $247.2-million and an internal rate of return of 34.9%, with a payback period of 1.6 years.