An evaluation of groundwater at the Gays River Mine, Halifax County, Nova Scotia

CIM Bulletin, Vol. 86, No. 975, 1993

T. Aston, Canadian Mine Technology Laboratory CANMET-EMR, Ottawa, Ontario, and T. Lamb, Westminer Canada Ltd., Milford Station Hants County, Nova Scotia

The Gays River Mine is located within a complex hydrological regime and underground mining environment. Early in the mine history, the operation was affected by an inability to control mine water inflows. More recently, the reopened mine operation had been unable to maintain consistent drainage of groundwater to the mine workings and sustain low groundwater levels. In 1992, a series of investigations were completed, which in part were funded under the Canada-Nova Scotia Mineral Development Agreement. The studies undertaken included: hydrochemical and drainhole well screen assessments, an air photo study of sinkhole features, numerical modelling studies and a major piezometer installation and overburden soil study. The results indicate that the water draining to the underground workings is comprised of two distinct components: precipitation over the drawdown cone catchment area and seepage from the nearby Gays River. In addition, a third "balance" component was also found, which represents uncertainties in the areal extent of the drawdown cone and river seepage components. After outlining the history of the groundwater problems experienced at the Gays River Mine, this paper examines the various studies undertaken during 1991-1992 and concludes that control of groundwater levels in the mine area is achievable. A number of recommendations are also proposed for future study.