Name and Location
Wassa underground gold project, Ghana.

Client
Golden Star Resources.

Project Description
The project involves the development of an underground mining operation at the currently operating Wassa openpit mine.

Access development to the underground stoping areas will be through a twin decline system from the north-east wall of the current Wassa openpit.

The twin decline system will ensure efficient ventilation during the early underground stages and will obviate the requirement for a raisebore ventilation raise and escape way close to the start of the decline. The main decline will be 5.8 m high and 5.2 m wide and be developed using standard trackless mechanised mining methods. The upper stopes will be mined using longitudinal longhole open stoping with waste rockfill. This will enable efficient early production before a cemented rockfill preparation and delivery system is installed. The Wassa openpit will eventually descend to the top of these upper stopes, but only towards the end of the life-of-mine.

In the deeper, wider areas of the deposit, a transverse longhole open-stoping method will be used. A primary-secondary mining sequence will be implemented, with the primary stopes filled with cemented rockfill and the secondary stopes with waste rockfill. The overall stoping sequence will be bottom-up to reduce the incidence of sill pillar development. New surface infrastructure to support the underground mining will be built, including electrical power supply from the grid, with backup genset support, and surface mechanical and electrical workshops. At steady-state production, the Wassa underground mine is expected to produce an average of about 2 000 t/d across the life-of-mine.

Net Present Value/Internal Rate of Return
The project has a net present value, at a 5% discount rate, of $176-million and an internal rate of return of 83% at a $1 200/oz gold price.

Value
Preproduction incremental capital expenditure for Wassa underground is estimated at $39-million.

Duration
Not stated.

Latest Developments
Most underground equipment for the development of the exploration decline was ordered in late 2014 and delivery is expected over the next three months.

An owner-operated team has been established at Wassa.

Starter-pit mining, which will host the two portals, has been completed and the preparations for the platform and the sumps for the declines have been established. The Wassa mine has received the necessary permits to start the exploration decline. The Wassa openpit mine is now fully established as a single large pit, which will operate separately from the two declines, resulting in the one decline having little impact on the others.

It is hoped that underground drilling will optimise the mine plan and potentially add more ounces to the resource base.

Key Contracts and Suppliers
Not stated.

On Budget and on Time?
Not stated.

Contact Details for Project Information
Golden Star Resources VP: investor relations Angela Parr, tel +1 416 583 3800 or email investor@gsr.com.