The PEA provides a robust base case assessment for developing the gold deposit as an underground dual ramp access mine with a central processing mill at the site.

Osisko is advancing surface and underground work at Windfall.

The PEA estimates that Windfall will produce 300 000 oz/y over the first seven full years of production.

The project can reach a peak recovery rate of 328 000 oz/y in year six, thereafter averaging about 238 000 oz/y for an 18-year mine life.

The project has an after-tax net present value of C$1.5-billion and an after-tax internal rate of return of 39.3%, with an after-tax payback period of 2.2 years from the start of production – assuming a gold price of $1 500/oz.

All-in sustaining costs will average $610/oz and the project has a capital expenditure estimate of C$544-million, including power line construction costs and C$55-million as contingency in direct and indirect costs.

The PEA assumes a 3 100 t/d milling operation, at an average gold recovery rate of 94.8%.

Windfall has the potential to generate more than C$8.2-million of gross revenue and C$1.7-billion in taxes. The project will create about 400 direct jobs and 200 indirect jobs during operation, while more than 500 jobs will be created during construction.

The independent PEA was prepared by engineering consultancy BBA Incorporated, based in Montreal.