Deep-well dewatering at Gibraltar Mines

CIM Bulletin, Vol. 73, No. 816, 1980

T.L CARPENTER Senior Mine Engineer, R. YOUNG, Assistant Chief Engineer, Gibraltar Mines Limited, McLeese Lake, B.C.

The presence of excessive water in the Gibraltar East Stage 1 pit initiated studies into the ground-water conditions that might be expected in mining the Granite Lake and Pollyanna pits. Hydrologic information obtained from a pump test program in 1974 indicated that deep-well dewatering could be successfully achieved. In 1976, a deep-well dewatering system consisting of eight wells was installed on the periphery of the Pollyanna pit. It has been responsible for a significant decrease in mining costs.This paper presents a brief summary of the engineering principles involved in the design of the Gibraltar dewatering system and the problems encountered in the installation and operation of deep-well pumps.
Keywords: Open-pit mining, Dewatering, Deep-well dewatering, Gibraltar Mines, Water flow, Granite Lake pit, Polyanna pit, Pumping, Falling-head tests.