The Bisha Mine is located in a semi-arid ecosystem, and accordingly, careful water stewardship is one of our most pressing economic, environmental, and social issues. Water is not only critical to mining operations, but access to water is an essential human right, as well as being essential to maintaining healthy ecosystems. We continually look for ways to minimize fresh water use and maximize water recycling to protect surrounding habitats and community water sources. We periodically review our mine water plan, monitor our daily water balance and consumption, and conduct regular water monitoring.

In 2014, we extracted a total of 1.93 million cubic metres (m3 ) of water for Bisha Mine operations compared to 1.5 million m3 in 2013 (a 29% increase). The increase was the result of higher water demand to process copper concentrate, as well as additional water used during the capital expansion program for the zinc plant.

All water used at the mine is drawn from groundwater resources (primarily the Mogoraib aquifer, as well as a lesser amount from dewatering the mine pit located in the Freketetet aquifer and an aquifer near the Harena pit). Rainfall also contributes to limited water resources, primarily supporting rehabilitation activities. Both the Company and two local communities (Mogoraib and Aderat) rely on the same aquifer located along the Mogoraib River. The remaining two aquifers supplying BMSC are not shared with any community due to distance.

 

Careful water stewardship is one of Nevsun’s most pressing economic, environmental and social issues. Water is not only critical to mining operations but access to water is also an essential human right, as well as being essential to maintaining healthy ecosystems.

Based on the results of the groundwater monitoring program (which are provided to the Eritrean Impact Review Committee), there is no evidence of impact to water quality to date. Water monitoring wells are located near the production wells to evaluate the impact on the aquifer dynamics. Even though the water level is showing a similar pattern during wet and dry seasons, there is an indication of a declining trend in the static water level of the boreholes at Mogoraib; especially those monitoring wells located close to production wells where a 1.18 m average decline has been measured since production started in early 2011. The measurements don’t necessarily signify a decline for the aquifer in general; however, to understand the potential medium and long-term impacts of extraction on the aquifer, more detailed hydrological investigations and groundwater modelling are required and are scheduled to take place in 2015/16.

BMSC has a water policy in place to maximize the efficiency of water use. The primary water demand at the mine is in the process plant. The mine water plan focuses on maximizing recycling and reuse of tailings pond and process plant water to meet those needs. BMSC employs two main methods of reuse, recovery via a thickener that returns water to the process plant before discharging the tailings, and a return water system that recovers water from the Tailings Management Facility (TMF) and returns it to the process plant for reuse. Water is considered a valuable resource and BMSC has initiated a study with the aim to further improve our ability to recover water from the TMF.

In 2014, approximately 305,365 m3 (15.7% of water use) was recycled from the TMF and returned to the plant as process water. This does not include water recovered by the thickener in the process plant that is also reused. On average, for every tonne of water sent to the TMF from the thickener, a tonne of water is recovered and reused in the plant.

Water quantity and quality monitoring is an ongoing and continuous activity onsite. Water samples are sent to a certified outside laboratory for analysis. In 2013, BMSC considered utilizing an in-house laboratory for sample analysis, but a review of the program in 2014 found that improved detection limits could be achieved by an outside certified laboratory and that efforts should focus on upgrading site sampling techniques and sample preparation.