A program of placer deposit sediment and water sampling was initiated by Indian and Northern Affairs Canada (DIAND) in the summer of 1998 to investigate possible relationships between the grain size distribution of pay gravels and effluent levels at Yukon placer mines. The sedimentology of placer deposits may be characterized in one way by examining the grain size distribution of pay (gold-bearing) gravels. In addition, the amount of clay and silt in gold-bearing gravels has a direct bearing on the treatment necessary for gold liberation during the placer mining process, and the resulting use of water for this process. The program consisted of sampling the pay or sluiced portion of an actively mined placer deposit (bank material), in conjunction with instrument monitoring and sampling the water upstream and at the discharge point of the mine.
Knowledge of the grain size distribution of pay gravels will allow interpretation of the fluvial depositional environment, which can be used as a tool for placer deposit exploration. Sampling and analysis of the water will result in the ability to relate the grain size distribution of the active mine site (bank material) to the suspended solids concentration of the water, and the subsequent impact mining of the deposits has on the water quality in the area. This data will be important for the complete review of the Yukon Placer Authorization in 2001.
